Respiration

and Guides to
oxygenation the essential
organs

A look
inside
the eye
Kidney
function •
explained

BOOK OF
How do our
muscles work?
THE

The evolution
/ ofthehand

Fracture
heaing
process

••
EVERYTHING YOU NEED TO KNOW ABOUT THE HUMAN BODY
Uncover
the science
of DNA
-\
- Explore the
sensory
system

Operating
on the
brain
How many
bones are in
afoot? Inside a
human heart

Anatomy of
. ...
fill- • '
.. •

-- the tongue Understanding

hormones
 Welcome to
BOOK OF

THE

The human body is truly an amazing thing. Capable of awe-Inspiring feats of

speed, agility and strength, while being mind-blowing In complexity, your
body ts unmatched by that of any otherspedeson Earth. In this updated
edition of How It Works Book of the Human Body, we celebrate the human
body's capabilities and beauty. as well as analyse bow it can be Impaired
or hampered. From how you bear, to how your digestion works, through
how your bones repair fractures and on to bow we express emotions and
experience touch, we explore the human body like never before. Packed full
of high-quality anatomical illustrations, detailed pbotographyand easy-to-
understand authoritative explanations. this book is Oiled with Incredible
facts thatwiU make you see yourself ina whole new light.
 magine P\blistW'lg ltd
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33 Richmond Hill
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Dorset BH2 6EZ
• +44 (0) 1202 586200
Website: www.~i'lg.oo.'*-
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This bookazine is fuby independent and not affiliated in any way with thG com.panios monUoned herein.

Kow tt Works Book of the Human Body Third RewiNd Edition C 2015 lm~ Publlthln& Lld

bookazine series

•••••••
PU8LISHINC
010 50 amazing body facts
018 Human cells
020 ruumJnating cells
021 Inside a nucleus
022 Stem cells
024 Bow do we smell?
025 Taste I Taste buds 028\
The power of
026 The tonsils your brain
027 Vocal cords
OJO Brain power 022
1 Whatare
OJ2 Vision and eyesight stem cells?
I
OJ4 Bow ears work
OJ6 All about teeth
oJ8 Anatomy of the neck
040 The human skeleton
042 Bow muscles work
044 Skin colour I Skin grafts
045 Under the skin
046 Rheumatoid arthritis
047 Bone marrow o66 The human ribcage
048 The human spine o68 How the pancreas works
050 Heart attacks 070 How your bladder works
051 Heart bypasses 072 Human pregnancy
052 Blood transfusions 074 Embryo development
053 Strokes I Blood dotting 076 Inside the human stomach
054 Human kidneys 078 Bow does angioplasty work?
056 Kidney transplants o8o The human hand
058 VestigJaJ organs o82 Nails I Knee-jerk reactions
o8J Inside the knee
""'-..
059 Bow the spleen works
010
o6o Human digestion 084 Bow your feet work Your body
explained
o62 Bow the liver works o86 Achil1es' tendon I Smelly feet
064 The small intestine o87 Blisten I Cramp

006
 110
Healing bone

--
fractures

/
o8o
The hand
revealed

---165
Explaining eye
adjustment

090 Food and the body

098 The blood-brain barrier
099 Pituitary gland up close
100 Brain electricity I Synapses
101 Adrenaline 142 /
The signs
102 Human respiration of ageing
104 Dehydration I Sweating
105 Circadian rhythm Curious questions 1

161 Correcting heart rhythms I

Salt I Adam' s apple
106 The immune system 142 Ageing
Seasickness I Rumbling
110 Bone fracture healing 146 Left or right brained? stomachs
111 Making protein 148 Brain freeze 16) What are moles?
112 The cell cycle 149 Runny nose I Comas 164 Brain control/ Laughing
114 White blood cells Dandruff I Eye adjustment I
150 Ears I Freckles I Sore throat Distance the eye can see
116 The science of genetics Memory I Toothpaste I
Epidurais 166 Allergies I Eczema
12.1 Burns
Blush I Caffeine I Fainting 167 Bruises I Water allergy I
12.2 Blood vessels Cholesterol
12.4 How your blood works 153 Eyebrows I Earwax I SeH 168 Alveoli
u.8 Hormones 154 72-hour deodorant I 169 Migraines/Eyedrops
Modem fillings
1)0 The urinary system 170 What are twins?
155 What powers cells?
1)2 Tracheotomy surgery 172 Paper cuts I Pins and
156 Can we see thoughts? needles I Funny bones
1)) Hayfever
158 How anaesthesia works 17) Aching muscles I Fat hormone
1)4 Exploring the sensory system
159 Stomach ulcers I Mouth ulcers 174 Raw meat I Inoculations I
1)8 Chickenpox Upper arm and leg
160 Hair growth I Blond hair
1)9 Whywecry I appearance 175 Feet size I Gout

007
 032
Inside the eye

028 010
How 50 fantastic
we think facts about
the body

o8o
The human
hand

025
/
Taste buds

""
0
Q

010 ~o amazin~ body facts 0)8 Anatomy of the neck

rom head o toe Impressive anatomical design
018 Bumancells 040 The human skeleton
How are they structured? Abounty of honey facts
020 mumina~ cells 042 Bow muscles work
Making cells g ow Muscle power revealed
021 Inside a nucleus 027 Vocal cords 044 Skin colour I Skin grafts
Dissecting a cell's control centre See how they help us talk Skin facts explained
022 Stem cells 028 Brainpower 045 Under the skin
Building block bring new life The human brain explored Anatomy of our largest organ
024 Bow do we smell? 0)2 The science of vision 046 Rheumatoid arthritis
A look at your nose Inside the eye How is inflammation caused?
025 Taste I Taste buds 0)4 Bow ears work 047 Bone marrow
The science of taste explained Sound and balance explained Why is this jelly vital to us?
026 The tonsils 0)6 All about teeth 048 The human spine
What are these fleshy lumps? Dental anatomy and more 33 vertebrae explained

008
 024
How do
we smell?
~

084
How your feet wctrk

050 Heart attacks o6o Human diraestion 076 Inside the human stomach
Why do they happen? How does ood get processed? How does this organ digest food?
051 Heart b~asses 062 How the liver works 078 How does ancftoflasty work?
How are ockages bypassed? The ultimate multitasl<er Inside the me ica procedure
052 Blood transfusions 064 The small intestine o8o The human hand
This vital procedure explained How does this organ work? Our most versatile body part
05) Strokes I Blood dotting o66 The human ribcage 082 Nalls I Knee-jerk reactions
Why do these occur? Offering essential protection A look at fingernails and more
054 Human kidne~s o68 How the ~ancreas works 08) Inside the knee
How do your ki neys function? The body s digestive workhorse See how it allows us to walk
056 Kidney transplants 070 How your bladder works 084 How your feet work
The booy's nafural filters Waste removal facts Feet facts and stats
058 Vestigial orf,ans 072 Human prepancy o86 Achilles' tendon I Smelly feet
Are ttiey real y useless? Nine months of growth explained Are they our weak spot?
059 How the spleen works 074 Embryo development 087 Blisters 1 cramfo
Learn how tt staves off infections The core processes revealed Why do blisters orm?

009
op so body facts
I•U•JW•1!113N•l!i'i> Useless body parts include the appendix the coccyx and w1sdom teeth

Pre-motor cortex
------ -
Frontal lobe . - - - - - - - - - Primary motor cortex
Howdo
l we think?
What are thoughts? This question wUI
The frontal lobe is where )'<lUI'
persmality is, and where )'<lUI'
lhcughts and emolians fonn.
Rem<Mng this or damaging it can
persona.
The primary motor cortex and the primary
somatosensory cortex are the a-eas wljch
receiYe sensory imervations and then
CXHlrdinate )'<lUI' whole r.l:1ge at~
keep scientists, doctors and
philosophers busy for decades to Parietal lobe
The parietal lobe is responsi>le for
come.ll all depends bow you want to
)'<lUI' complex sensory system
define the term 'thoughts'. Scientists
may talk about synapse formation,
pattern recognition and cerebral
activation in response to a stimulus Bloca's - - + -;;.;..;;;
(such as seeing an apple and - Primary auditory
area complex
recognising it as such). Philosophers, Btoca'sareais The primary auditory
andalsomanysdentists, will argue when! lJOU form complex is ri~ next to
that a network of neurons cannot complex words the ear and is where you
possibly explain the many thousands and speech interpret sound waves
of thoughts and emotions that we patterns. into meaningful
must deal with. A sports doctor might infonnation.
state that when you choose to run, you
activate a series of well-trodden Temporal lobe
pathways that lead from your brain to The temporal lobe decides what to Occipital lobe
do with SOl.l1d information and also The occipital lobe is all
your muscles in less than a second.
combines it with visual da
~ta.
~::;:=----- the way at the back, but
There are some specifics we do know it inlet po ets the light
though-suchaswhlchareasofyour Wernicke's area is where lJOU interpret
.___ signals in )'<lUI' eyes into
brain are responsible for various types L...- the language )IOU hear, and then )IOU
sllapes and pattems.
W11 fonn a response via Broca's area.
of thoughts and decisions.
----- ·-- ~.-------

' S Whycan
: some people
roll their
tongues but
: others can't?
i
!
Do eyeballs
3
Although we're often taught In school that
I tongue rolling Is due to genes, the truth Is
grow like the likely to be more complex. There Is ll.kely
to be an overlap of genetic factors and
rest of the body? envlronmentallnOuence.Studleson
Only a small amount families and twins have shown thalli
~ - hence why babies I
cannot be a case of simple genetic
. inheritance. As!< around- the facttbat
1nthe appear so beautiful, as some people can learn to do It suggests

2 mornings, I their eyes are slightly

out of proportion and
that in at least some people It's
environmental (ie a learned behaviour)
rather than genetic (Inborn).
do we wakeup I so appear bigger.
oro~J@n our
eyes first? Why do we fiddle
subconsciously?
Sleep is a gift from nature, which Is
more complex than you think. There I'm con ntly
are five stages of sleep whlch represent
the increasing depths of sleep - when
you'resuddenlywldeawakeandyour
eyes spring open, it's often a natural
playing with my hair
This is a behavioural response -
some people play with their hair
when they're nervous or bored. for
I
(
I
awakening and you're coming out of
rapid eye movement (REM) sleep; you
the vast majority of people such
traits are perfectly normal; if they I
I
maywellrememberyourdrearns.lf : begin to interfere with your life,
you're coming out of a different phase, behavioural psychologists can help
eg when your alarm clock goes off, It i -but it's extremely rare that you'll
will take longer and you might not ! end up there. :
want to open your eyes straight awayI I i

011
 op so body facts
What's my Why do
2Dfield - - - - - - - .
The a-eas from 120 1D 180
dog! ees are seen as 20 as
odi one eye <Uib ibutes, but
we don't really nOOce.
(
l
r.: .. 7
in degrees?
1
field of vision · we burp?
Aburp is a natural
Thehumanfieldofvlslonlsjustaboutt8o release Of gas from
;
the stomach. This gas
~
degrees. The central portion of this
I has either been
(approximatelyuodegrees)is binocular or
30field- - - - -- '
The central 120-degree
0 stereoscopic- ie both eyes contribute.swallowed or is the
portion is the 30 part of
: :!':::;~:~!~~~i~t:d~~O:~~we can 1 result of something
oor vision as both eyes
contribute - this is tt.e part
we use the most •
~ monocular. meaning that there Is no
overlapfromtheothereyesoweseelnzD.
Q
I
you've ingested-such
as a fizzy drink. The
__.....,.......--······---········--·-·--·····-----··--·--,.-...-...-...-.·----·····..·-·--- ~···- ....... - .... ····· ·• sound comes from the
Whatis ! n How fast does I vibration of the
8
of tonsils?
the P.Oint
I
!
! the human body?
bl 00 d t rave roun 1 d oesophageal
. sphincter at the
1·

I
oesophago-gastric
The tonsils are collections of
I
Your total 'circulating volume' Is about five lltres. Each
I red blood cell Within this has to go from your heart.
• junction, which is the
! narrowest part of the
lymphatic tissues which are : down the motorway-Uke arteries, through the
thought to help fight off
pathogens from the upper
I back-road capillary system. and then back through the gastrointestinal tract.
i rush-hour veins to get back to your heart. The process
respiratory tract. However,
they themselves can
j typically takes about a minute. Whenyou're ln a rush
sometimes become Infected-
! and your heart rate shoots up, the time reduces as the
· blood diverts from the less-Important structures (eg
leading to tonsillitis. The ones i large bowel) to the more essential (eg muscles).
you can see at the back of your •
!
throat are just part of the ring
of tonsils. You won't miss them !' L The most ---... 2. Under pressure i
if they're taken out for , important organ Blood is moving fastest
: The bra01 has its own and under the highest
recurrent Infections as the
rest of your immune system i special blood supply pressure as it tea...s the
1
i ara)Qedinaade. heart and enters the
will compensate. !: elastic aorta.
i
i
!
'
~

Howmany
11QWhy does it feel so weird when
~ you hit your funny bone?
I
!
I 13 inches of
hair does the
You're actually hitting the ulnar ne.rve as It wraps around the bony
prominence of the 'humerus' bone, leading to a 'funny' sensation.
Ii 4. The inferior
vena cava
This mas.sNe vein sits
averay~rson
; grow their
Although not so funny as the brain Interprets this sudden trauma betWldtheaorta but is S. lhe
as pain to your forearm and fingers!
i
.:
! no poor relation- furthest point head each year?
i without it, blood These arteries and It's different for everybody-your
l woUdn't get bad< veins are the furthest age, nutrition, health status. genes
!! to )'Ot.l' heart.
-from )'Ot.l' and gender all play a role. In terms
heart. and blood flow
of length, anywhere between
'. 3. The kidneys
! here Is-·As you
grow older, these 0.5-tlnch (1.2-2-5Cm)a month
l Thesedemand a mas.sNe vessels are often the might be considered average,
but don't be surprised if you're
! 25 per cent of the blood first to get blodo!d by ;
t from each heart beat! fatty plaques. outside this range.

012
 • •• •• •
•
• • • ••
•• Sneeze fast! • Red blood cells •• Hard liVOI'ker •• Liquid
STOP 1
Emotions
While great apes sudlasgorilas, :2
• A sneeze is typically expelled at •
•
• 3 Red bloodoells • also known
•
• 4 Theheartbeatsonaverage
•• s Humans are made up of 70 per

FACTS chimps and orang·utans use facial

expressions to show their
•
•
••
a"""d J6lkmlh ()OOmpl1).
Sneezing helps protect the body ••
••

••
as erythrocytes • live on
<J\Ief'age for 120 days. There
••
•
•••
100,000 timE5 per day. Of
co...se this wil greatly vary
••
•••
cent water, which is essential
lor body growth and I'EpiW. The

BODY feelings, h...-nan beings are the

only animals known to cry as a
••
••
by ...,p;ng the nose free of
bacteria and viruses. There's a ••
are approximately 25 trilion
red blood cells in your body at •
•
depending on your level of
activity and you-
•
••
NHS suggests drinking L2
~tres of water a day to avoid
ROUNDUP result of theiremotions.
• video on our website. •
• any given moment. •
• environnental conditions. •
• ~ngdecyd...-

ltU•JU•11J!3N•IW The overage person breaks wind between 8-16 times per day

Whyare !
14
fi~gerprints
everyone's !
!
different? I.
Your fingerprints are fine ridges of
skin in the tips of your fingers and
toes. They are useful for improving
the detection of small vibrations
and to add friction for better grip.
No two fingerprints are the same
-either on your hands or between
two people-and that's down to
your unique set of genes.
l7 Why do we all
have different
coloured hair?
Most of it Is down to the genes that result
Why do from when your parents come together to
make you. Some hair colours win out
we only (typically the dark ones) whereas some (eg
blonde) are less strong in the genetic race.
remember
some dreams? 1s it possible to
Dreams have fascinated humans
for thousands ofyears. Some
18 keep your eyes
open wtlen you sneeze?
people think they are harmless Your eyes remain shut as a
while others think they are vital to defence mechanism to prevent
our emotional wellbeing. Most the spray and nasal bacteria
people have four to eight dreams entering and infecting your
per night which are influenced by eyes. The urban myth that
stress, anxiety and desires, but your eyes will pop out Uyou
they remember very few of them. keep them open is unlikely
There is research to prove that U to happen- but keeping
you awake from the rapid eye them shut will provide
movement (REM) part of your sleep some protection against
cycle, you're likely to remember nasty bugs and viruses.
1~6Why, as we your dreams more dearly.
~ get older,
does hair growth
become so erratic?
Hair follicles in different parts of your
body are programmed by your genes to
do different things, eg the follicles on
your arm produce hair much slower
than those on your head. Men can go
bald due to a combination of genes and
hormonal changes, which may not
happen in other areas (eg nasal hair).

-
It's different for everybody!
- _.. ...._.................................................-.........................................-
........_................. .............................. .......,_............ ..............,_....................,......
~ , .....................

What gives me
l9 my personality?
Researchers have spent their whole lives trying to
answer this one. Your personality forms in the front
lobes of your brain, and there are clear personality
types. Most of it is your environment- that is, your
upbringing, education, surroundings. However some
ofit Is genetic, although it's unclear how much. The
strongest research in this comes from studying twins
- what influences one set of twins to grow up and be
best friends, yet in another pair, one might become a
professor and the other a murderer.

013
 op so body facts
--------------~~-- ----------------------------------------------------
What makes some blood What is a pulled
muscle?
others are universa ?
Your blood type is determined by protein markers known as antigens on the surface ofyour The hamstrings
red blood cells. You can have Aantigens, Bantigens, or none - in which case you're blood type These are a !1'0UP of
Strain
0. However, if you don't have the antigen, yourantlbodleswlll attack foreign blood. if you're A puled rruscle. or
ttree main fT'lJSdes
type Aand you're given B, your anllbodles attack the Bantigens. However, if you're blood type strain, is a tear i1 a 47tJUP
which flex the knee.
AB, you can safely receive any type. Those who are blood group 0 have no antigens so can give at rn.osc:le filres as a
re5lAt of CO\II!<Stretching.
blood to anyone, but they have antibodies to Aand Bso can only receive 0 back!
A
• • YouhaveAantigensandB
• , ~ ., .,.._ an!lbodles. Youcanreceiveblood
• , - • groupsAandO,butcan'trecelveB.

._....
- • •
•

, • • •
YoucandonatetoAandAB.

8
YouhaveBantlgensandA
~ • • ~.,.._ antibodies. You can receive blood
I
• •• • groups Band O, but can't receive
A. You can donate to BandAB.

• • AB
•• You have Aand B antigens and no
• . • •
,
'
. .. .
~ '
• • • .-
, • f
antibodies. You can receive blood
groupsA,B, ABandO(Uiliversal
recipient), and can dooa!e toAB.

0
You have no antigens buthaveAand B Though warming up can belp prevent
;..-- antibodies. Youcanreceivebloodgroup sprains, tlley can happen to anyone.
O, butcan' treceiveA.BorABandcan from walkers to maratbon runners.
donate toall: A. B, ABand 0. PulledmusdesaretreatedwilbRICE:
rest,. lee. compresslonandelEwtlon
... ,_. ·- ·----:-;;::::=:::;
__j ;;:.,
What is the
28 aP.~ndix? I've
heard it has no use
but can kill you••.
The appendix Is useful in cows for
d lgesllng grass and koala bears for
digesting eucalyptus- koalas can have
a 4ffi (tJft)-longappendlxlln humans,
however, the appendix has no useful
function and Is a remnant of our
development. It typically measures
5-tocm (1.9-).9ln), but if it gets blocked it
Which
27 organ
uses up the
cangetlnflamed.lflt Isn't quickly
removed, the appendix can burst and
lead to widespread Infection which can
be lethal.
most oxygen?
The heart is the most
efficient- it extracts
What 3. Vagus nerve
8o per cent of the is the The V"!J..S """"' is stim.Jiated,

oxygen from blood.

But the liver gets the
gag reflex? leading to forceful a> olla:tion
at the stomach and cfli!llhra!1n
to expel the object forwards.

most blood- 40 per L F<lr'e91 bodies

TNs is a PiotectM! mechanism to ~X'£"~'!01
cent of the cardiac food or lan!;gn bodies e otei og the back at
output compared to the throat at times- than swabNing.

the kidneys, which 4. Thegag

TNs forceftJ expoolsK>n
get 25 per cent, and 2. Soft palate leads to 'gagging', which
heart, which only
receives 5 per cent. I The scft palate (the fleshy part at the
mouth roof) is strn.Jiated, sending signals
downthe~hal)'ngeal........,,
can develop into retd:ling
and vomiting.

014
 .,....... 2. Human i:lta:r 3. Human
HEAD2 ~~~~: vscheetah
l.Human
vsgiraffe vsflea
HEAD .'~'1$~! ~
While the mrld rE!C<ll'd The average man In England The men's outdoor high
hoi de( Usain Bolt can run It Is L7m (55ft) tall. The jump wortd (eoo(d is 2.4Sm

HUMANS VS .Jf \ '1~ ~ can run lOOm (328ft) in

io 9.58 seconds, a cheetah tallest 1'1'\an ever was 2.7m
(8.8ft). A giraffe can grow
(less than twice the height
of a man). A flea can jump
ANIMALS '- . • just ovet six seconds. up to 6m 0 9.7ft). up to 100 times Its heighL

ltU•Wi•IIJ!3N•IW Your broin interprets poin from the rest of the body, but doesn't hove ony poin receptors itself

l 3 2Why don't eyelashes

! keep growing?
I, Your eyelashes are formed from hair follicles, just like those on your
head, arms and body. Each follicle is genetically programmed to
j function differently. Your eyelashes are programmed to grow to a
i certain length and even re-grow if they fall out, but they won't grow
; beyond a certain length, which Is handy for seeing!
i
!
i
j
!
j
:
i
i
;...-_, l
j
•
~
i .__,..,
:
!

34~~uld
1

Whyarewe
.!
l
!
33=resus
left-handed? surv1ve on
•

vitamins
31ticl<lish? i! One side of the brain is
typically dominant over the alone?
Light touches, by feathers, spiders, insects or other 1
other. Since each hemisphere No, you need a diet
humans, can stimulate fine nerve-endings in the skin
which send impulses to the somatosensory cortex in the
brairL Certain areas are more ticklish - such as the feet -
II
:
of the brain controls the
opposite side (ie the left
balanced in
carbohydrate,
controls the right side of your
which may indicate that it is a defence mechanism ! body), right-handed people protein, fat,
against unexpected predators. It is the unexpected
nature of this stimulus that means you can be tickled.
Although you can give yourself goosebumps through
I have stronger left brain
hemispheres. Occasionally
you'll find an ambidextrous
vitamins and
minerals to survive.
light tickling, you can't make yourself laugh. iI You can't cut one of
person, where hemispheres
..........-·--···..........................- ...- ........- ..- .........................- •••- ....1 are co-dominant, and these these and expect to
! people are equally capable stay healthy.
.! with both right and left hands! However, it's the
I
i
proportions of these
which keep us
!
l healthy and fit. You
' can get these from
I the five major food
groups. Food charts
I
I
f
l
can help with this
balancing act.
..............•••..,.........•••..,...-...'9....,.....,, .. ,,,, 0 0Ooooo_..,.....,.,...,"",-..._o-H-••>•••-••t>H_..no•oo_o_..•..._.., ..
""~•-• •o'9••

Wh dowegeta
when we're ill.
The immune response leads to inflammation and the release of
inflammatory factors into your blood stream. These lead to an
increased heart rate and blood flow, which increases your core body
temperature - as if your body is doing exerdse. This can lead to
increased heat production and thus dehydration; for this reason, it's
important to drink plenty of clear fluids when you're feeling unwell.

015
 op so body facts
What triggers
39 the heart and
keeps it beating?
The heart keeps Itself beating. The
sinoatrial node (SAN) is in the wall of the
right atrium of the heart, and is where the
heartbeat starts. These beats occur due to
changes In electrical currents as calcium,
sodium and potassium move across
membranes. The heart can beat at a rate of
6o beats per minute constantly if left alone.
However- we often need it to go faster. The
sympathetic nervous system sends rapid
signals from the brain to stlmulate the
heart to beat faster when we need it to- in
'fight or Olght' scenarios. If the SAN fails, a
pacemaker can send artificial electrical
signaIs to keep the heart going.
L Atrial systole Definitions
The atria are the 2 Ventricular systole 3. Ventricular diastole Systole=oontractlon;
low-pre5Slft- The lll!ntrides contract next, The heart is rcw relaxed a:>d can Diastole= relaxallon
chambers, a:>d are the a:>d they send hql-pre5Slft refill, ready for the next beat.
mt to contract, emptying blood out into the aorta to
supply the body.

I
Why do bn.lises go
40 purple or yellow?
Abruise forms when capillaries under the skin leak and allow .'
I
I
I
41=
cutting
blood to settle in the surrounding tissues. The haemoglobin in J
red blood cells is broken down, and these by-products give a
onions make
dark yellow, brown or purple discolouratlon depending on the ' us cry?
volume of blood and colour of the overlying skin. Despite Onions make your eyes water due to their expulsion of
popular belief, you cannot age a bruise -different people's an irritant gas once cut. This occurs as when an onion
bruises change colour at different rates. is cutwitha knife, many of its internal cells are broken
down, allowing enzymes to break down amino acid
1. Damage to the
3. Discololration
Haemoglobin is then
sulphoxides and generate sulphenic acids. These
sulphenic acids are then rearranged by another
Why do
blood vessels
After trauma such as a faR,
broken down into its
smal~ components, which
j enzyme and, as a direct consequence, syn-
propanethial-5-oxide gas is produced, which is volatile.
more
the small capillaries are
tom and burst
are what giw the dark I
This volatile gas then diffuses in the air surrounding men go bald
discololo'ation of a bruise. i
.the onion, eventually reaching the eyes of the cutter,
than women?
Iwhere it proceeds to activate sensory neurons and
2. Blood leaks create a stinging sensation. As such, the eyes then 'Simple' male pattern baldness is due
into the skin
Bk>od settles into the
'
. follow protocol and generate tears from their tear
• glands in order to dilute and remove the lrrlta nt.
to a combination of genetic factors
and hormones. The mostimplicated
! hormone ls testosterone, which men
tissues SUTOU'lding the Interestingly, the volatile gas generated by cutting
vessel. The pressure , onions can be largely mitigated by submerging the have high levels of but women have
from the bruise then onion in water prior to or midway through cutting. low levels of, so they win (or lose?) in
~stem the bleedio~g. this particular hormone contest!
• with the liqtlidabsorbing much of the Irritant

'
-
42:!'ft~e I 4 3 When we're
tria~le sha~ I tired, why do
on the side Of
the ear? ! we get bags under
This Is the tragus. It serves
no major function that we
: our eyes?
Blood doesn't circulate around your body as
knowot butltmayhelpto
efficientlywhen you're asleep so excess water can
reOect sounds Into the ear
to Improve hearing. pool under the eyes, making them pulfy. Fatigue,
nutrition, age and genes also cause bags.

016
 The heart is amazing
It stimulates its own heartbeat, beats around 1oo,ooo times a day and pumps
about 2,ooo gallons of blood per day. It's also the most efficient of organs and
extracts the highest ratio of oxygen per unit of blood that it receives. The heart
has its own blood supply too that supplies its muscular wall.

ltU•JU•11J!3N•IW The hyoid is the only bone that isn't connected to another bone - it sits ot the top of your neck

II 4 7Whydowe Why do some

get itchy? hereditary
! Itching Is caused by the release of a conditions skip a
I transmitter called histamine from
j mast cells which circulate in your body. generation?
:· These cells are often released In Genes work in pairs. Some genes are
1, response to a stimulus, such as a bee
! sting or an allergic reaction. They lead 'recessive' and if paired with a
l to inflammation and swelling, and
! send impulses to the brain vla nerves
'dominant' half, they won't shine
through. However, if two recessive
which causes the deslre to itch.
genes combine (one from your mother
and one from your father), the
recessive trait will show through.

we link?
Blinking helps keep your eyes clean and moist Blinking
spreads secretions from the tear glands (lacrinlal fluids)
over the surface of the eyeball, keeping it moist and also
sweeping away small particles such as dust.
____ .............-~--··-··--······-··-·..................... ____~-·-·-·······-~:
...., ...._

j
ISQWhich muscle produce~ the
1 most_powerful contraction
i relative to its size?
j The gluteus maxinlus is the largest muscle and forms the bulk of your buttocl<. The heart (cardiac muscle) is
! the hardest-working muscle, as itis constantly beatingand clearly can never take a break! However the
! strongest muscle based on weight is the masseter. This is the muscle that clenches the jaw shut- put a
! finger over the lowest, outer part of your jaw and clench your teeth and you'll feel it

I
Myosin head Actin filament
t Actin filament
is pulled

I. c._----=======...
j 1. Taking the first step 2. Preparation
•
! Musclecontract!onslartswithanlmpulserecel\ledfromthe The calcium binds to troponin which Is a receptor on
j nerves supplying the muscle - an action potential. Tbis the actin protein. This binding changes the shape of
j action potential causes calcium Ions to flood across the tropomyosin. another protelnwbich Is bound to actin.
! protein muscle fibres. The musde fibres are formed from two These sbape changes lead to the opening of a series of
key proteins: actin and myosin. bindlngsltes on the actin protein.

How come most ~- Energised myosin

head
people have one foot
larger than the other? !
Most people's feet are different sizes-in fact the two !• 3. Binding 4. Unbinding
halves of most people's bodies are different! We all start !' forge
Now the binding sites are free on actin. the myosin beads
strong bonds in these points. Tbis leads to the
Wben the energyrunsou~ the proteins lose their strong
bonds and dlseng;~ge,and from there they return to
from one cell, but as the cells multiply, genes give them ,• contraction of the newly formed protein complex; wben all their original resting state.
varying characteristics. 1 of the protelnscontrac~ the muscle bulk contracts.

017
 Cells under the microscope
Cell membrane
St.mxning and "'ippOI ti '!I
each eel is a plasma mea ba-.e
that ""' lb uls ewrything that
entErs and exits.

Nucleus --------~
The nucleus is the cell's 'brain'
ex control centre. Inside the
There are around 75 trillion cells nucleus is DNA infonnation,
which explains how to make
in the human body, but what are the essential proteins needed
to""' the eel.
they and how do they work?
.:*~-
,. Cells are life and cells are
a live. You are here because
every cell inside your body
... has a speclllcfunctlonand a
Ribosomes - - - - - - - - - - - . . .
These tiny structures make proteins and
can be fol.lld either floating in the
cytoplasm or attached ike studs to the
very specialised job to do. There are endoplasmic rt'ticulllll, which is a CO"""Y''"
many different types of cell., each one belt-like membrane that transports proteils
working to keep the body's various around the eel.
systems operating. Asingle cell Is the
smallest unitofliving material In the
body capable of life. When grouped
together In layers or clusters, however,
cells with similar jobs to do form tissue,
such as skin or muscle. To keep these
ceUsworking, therearethousandsof Endoplasmic reticulun - - - -
The - o f folded memblanes (ca>als)
chemical reactions going on all the time. oonnecting the nucleus to the cytoplasm are
All animal cellscontaina nucleus. called the endoplasmic relicuk.m (Ell). If
which acts like a control hub telling the studded witll ribosomes the ER is refeoed to
cell what to do and contains the cell's as "rou!to' ER; if oot it is known as '5mooth'
genetic lnformation (DNA}. Most of the E:R. Both~ transport materials around the
material within a cell is a watery, cell but also haw diffe 0"19 functioos.
jelly-like substance called cytoplasm
(cyto means cell}, which circulates
around the cell and is held In by a thin
external membrane, which consists of
two layers. Within the cytoplasm Is a
variety of structures ca lied organelles. Smooth - --...J
which aU have different tasks, such as endoplasmic
manufacturl ng proteins- the cell's key
reticulum
chemicals. One vital example of an
organelle Is a ribosome; these numerous
structures can be found either floaU ng
around in the cytoplasm or attached to
Internal membranes. Ribosomes are
crucial in the production of proteins R~h~ic ------------­
from amino adds. reticulum (studded
In turn, proteinsareessenUal to with ribosomes)
buildl.ngyourcellsand carrying out the
biochemical reactions the body needs In
order to grow and develop and also to
repair itself and heaL

Golgi body - - - - - - - '

Mroxboodria ------~ Another organele. the Golgi body is one
Theseorganeles ~eels witlltheenergy that processes and packages protOOs.
necessary for them to cany out their functioos. including ton oones and enzymes. for
The atn01.1>t of energy used l>y a cell is mea5l.l1!d transportation either in and around the
in molecules of adenosine IJ1>hosphate (ATP'). cell a out towards the membrao oe for
Mitoc:hondria use the products of~ seaetion outside the eel where it can
metabolism as fuel to llfoduoe the ATP. enter the bloodstream.

018
 Super cells
Stem cells are self-renewing cells with the potential to become any other
type of cell in the body. Unlike regular cells, they do not have a spedalisation,
such as nerve cells. Experts have discovered that adult stem cells can be
manipulated into other types with the potential to grow replacement organs.

ltU•JU•11J!3N•IW Bacteria ore the simplest living cells and the most widespread life form on Earth

anatomy
,..--- Cytoplasm
Types of human cell
This is the jelly·l ike
substance - made of
So far around 200 different varieties of cell have been
water, amino acids and identified, and they all have a very specific function to
enzymes - found inside
the cell membrane.
perform. Discover the main types and what they do...
Wrthin the cytoplasm are
organelles such as the
NERVE CEliS move.Wecancontrolskeletalmusclesbecausethey
Thecellsthatmakeupthenervous arevoluntary. cardiac muscles, meanwhile, are
nucl~ mitochondria
system and the brain are nerve ceUs Involuntary, which Is fortunate because they
and ribosomes, each of
orneurons. Electrlcalmessages are used to keep your heart beating. Found In
which perfcxms a specific the wails of the heart, these muscles create
pass betweennerveceUsalong
role, causing chemical their own stimuli to contract without Input
longffiarnents caJJed axons. To
reactions in the cross the gaps between nerve from the brain. Smooth muscles, which are
cytoplasm. ceUs (the synapse) that electrical pretty slowand also Involuntary, make up
signal Is converted into a cbernical the llnlngsofhoUowstructuressuchas blood
signal. These ceUs enable us to feel vessels andyour digestive tracL Their
sensations, such as pain, and they also wave-like contraction aids the transport of blood
enable us to move. around the body and the digestion of food.
- - • - • • • o oooo,..ooo ouooooo-uooooo. .._ , _ , , , ,, , _• .,,,..,,,,, ••-••• ' ' ' ''''""'

BONE CEliS FAT CEliS

Thecellslhatmakeupbonematrlx- thehard These ceUs- also known as
structure that makes bones strong- consist of three adipocytesor lipocytes-
main types. Your bone mass is constantly changing make up youradipose
and reforming and each of the three bone ceUs plays Its tissue, or body fa~ which
part In this process. First the osteoblasts, which come can cushion, Insulate
from bone marrow, build up bone mass and and protect the body.
structure. These ceUs then become This tissue Is found
burled in the matrix at which beneath your skin and
point they become known as also surroundingyour
osteocytes. Osteocytes make other organs. Theslzeofa fat
up around 90 percent of the ceU can Increase or decrease
cetlsIn your skeletonand are dependingon the amountof
responsible for malntalnlng energy It stores. Uwegaln weight the ceUsli!J with
the bone material Finally, more watery fat. and eventually the number offat ceUs
while the osteoblastsadd to wtll begin to Increase. There are two types of adipose
bone mass, osteoclasiS are the tissue: white and brown. The white adipose tissue
ceUscapable of dissoMng bone stores energyand Insulates the body by maintaining
and changing its mass. body heat The brown adipose tissue, on the other
band. can actually create heat and Isn't burned for
PHOTORECEPTOR m IS energy- this Is why animals are able to hibernate for
The cones and rods on the redna at
the back of the eye are known --··~......... ·-"···---· ·---- --
monthsonendwithoutfood.
Et11 HELl AI. CR I 5
.... ..... .......-..._.._ ...
as photoreceptorceUs. These
contain light-sensitive Epithelial cells make up the epithelial tissue that
pigments that convert the lines and protects your organs
Image that enters the eye and constitute the primary ,
Into nerve signals, which material ofyour skin. •
the brain Interprets as These tissues forma ••
pictures. The rods enable you barrier between the
preclousorgansand .~
,
to perceive light, dark and
movement, while the cones unwanted pathogens or
brlngcolourtoyourworld. other fluids. As well as
..-..............................................-.............................................
_~ ....................... coverlngyoursk!n, you'U
LJVERCEiiS lind epithelial CeliS Inside ,
- - - ..,. Tbe cellsInyour liver are responsible your nose, aroundyour lungs
for regulating the composition of
yootr bl•ood.Tbese ceUsffiter out
toxlnsasweUascontrollingfat,
and In your mouth.
RED BLOOD CEil S
- -
_. .................................. ..... .. . ...........................................
~

sugar and amino acid levels. Unlike aU the other cells In your
Around Soper cent of the liver's body. your red blood ceUs(also
mass consists of hepatocytes, known as erythrocytes)do
which are the liver's speciaUsed not contain a nucleus. You
ceUs thatare Involved with the are topped upwtlh

MUSCLE CEll S
production ofproteins and bile.
--
........_..._.... __........... ..-............. -- ..
............_ around 25 trillion red
blood cells- that'sa third
-;;tJ:~~~J- of aUyourceUs, making
There are three types of musde ceU- 1 " them the most
skeletal,cardiacandsmooth- and common ceU In
eachdlfiersdependlngonthe your body. Formed
function It performs and Its location In the bone marrow,
Lysosomes In the body. Skeletal musdes these ceUs are important
This digestive enzyme breaks down contain long fibres that attach to because they carry oxygen to au the
unwanted substances and worn-out bone. When triggered by a nerve tissues In your body. Oxygen Is carried In
organeHes that could hann the cell by signal, the musde contracts and haemoglobin, a pigmented protein that
digesting the product and then pulls the bone with it, making you gives blood cells their red colour.
ejecting it outside the cell.

019
 ·ng cells glow

uminatin
Find out how GFP and quantum dots are shedding Bioluminescence
light on medical research... in nature
Hundreds of living organisms produce
light, although most do not fluoresce,
For millions of years, the Aequorea track their movement and interaction. Tagging the instead getting their glow from
victoria jellyfish held the secret to HIV virus with GFP, for instance, shows how the chemical reactions. Most of these are
marine creatures and bacteria,
green fluorescent protein (GFP) - a infection spreads.
although terrestrial invertebrates (eg
protein that absorbs the energy from Asimilar effect can be achleved with q uanturn fireflies, inset) and fungi can also
the blue and ultraviolet (UV) range andre-emits it as a dots - nanoscale semi-conductor crystals which glow. Bioluminescence serves a
variety of functions. In many marine
green light Biologists got their hands on the glowing also fluoresce under UV light. The dots can be
animals, it provides camouflage by
jeUyfish in the Sixties, extracting the protein and made in many different colours and bound to aBowing its bearer to blend in with
then uncovering the gene that codes for it. proteins, allowingsdentists to observe complex the surrounding light when viewed
from below. In othet- species it is used
By inserting this sequence into living orga nlsrns, biological interactions.
as a form of convnunication or, like
scientists equip them with the instructions that are Recently, surgeons wearing special goggles the anglerfish, to draw in prey.
required to manufacture GFP, highlighting how identified and removed cancerous cells highlighted Researchers aren't certain what the
Aequorea victoria jellyfish uses its
genes are expressed in everything from bacteria with quantum dots. These goggles could also be
eerie GFP glow for, but some believe
to human cells. Spedfic proteins and cell types used to develop diagnostic tests and therapies for it may be to evade predators.
can be tagged with GFP, allowing researchers to other conditions.

020
I•U•JW•1!113N•l!i'i> Ribosomes are responsible for making proteins out of omrno ocrds

• Central command
ns1 eanu eus Take a peek at what's happening inside
the 'brain' of a euk aryot ic cell
0 Nuclear pore
Dissecting the control centre of a cell These channels control the movement or molecules
Surrounded by cytoplasm, the responsible for making proteins out of amino between the nucleus and cytoplasm.
nucleus contains a cell's DNA acids which take care of growth and repair. @ Nuclear envelope
and controls all of its functions Being so important, the nucleus is the Act s as a wall to protect the DNA within the nucleus
and processes such as movement most-protected part of the cell. in animal cells and regulates cytoplasm access.
and reproduction. it is a lways located near its centre and away ~Nucleolus
There are two main types of cell: eukaryotic from the membrane to ensure it has the Made up of protein and RNA, this is the heart of the
and prokaryotic. Eukaryotlc cells contain a maximum cushioning. As well as the jelly-like nucleus which manufactures ribosomes.
nucleus while prokaryotic do not. Some cytoplasm around it, the nucleus itself is filled 0 Nucleoplasm
eul<aryoticcells have more than one nucleus- w ith nucleoplasm, a viscous liquid whjch This semi-liquid, semi-jelly material surrounds the
called multinucleate cells- occurring when maintains its structural integrity. nucleolus and keepS the organelle's structure.
fusion or division creates two or more nuclei. Conversely, in plant cells, the nucleus is more 0 Chromatin
At the heart of a nucleus you'll find the sporadically placed. This is due to the larger Produces chromosomes and aids cell division by
nucleolus; this particular area is essential in vacuole in a plant cell and the added protection condensing DNA molecules.
the formation of ribosomes. Ribosomes are that is granted by a cell wall.

Nucleus in context /
Explore the larger body t hat a nucleus
rules over and meet its 'cellmates•
0

How do cells
survive without
a nucleus?
Double membraned. Prokaryotic cells are much more basic than their
Made up of two separat e this produces energy for eukaryotic counterparts. Up to 100 times
entities, ribosomes make the cell by breaking smaller and mainly comprising species of
proteins to be used both down nutrients via bacteria, prokaryotic cells have fewer functions
than other cells, so they do not require a nucleus
to act as the control centre for the organism.
Instead, these cells have their DNA moving
Golgi apparatus around the cell rather than being housed in a
Named after the Italian Lysosome nucleus. They haye no chloroplasts, no
biologist Camillo Golgi, Small and spherical. membrane-bound organelles and they don't
this organelle contains undertake cell division in the form or mitosis or
digestive enzymes that meiosis like eukaryotic cells do.
Prokaryotic cells divide asexually with DNA
molecules replicating themselyes in a process
known as binary fission.
 at are stem ce •
Understand how these building blocks bring new life
Stem cells are incredibly proliferation- while others such as
special because they nerve cells don't divide at all. Cloning cells
have the potential to There are two stem cell types, as Scientists can reprogram
become any kind of cell Professor Paul Fairchild, co-director cells to forget their
in the body, from red blood cells to of the Oxford Stem Cell Institute at current role and become
pluripotent cells again
brain cells. They are essential to life Oxford Martin School explains: - indistinguishable from
and growth, as they repa lr tissues "Adult stem cells are multipotent, early embryonic stem cells. These
and replace dead cells. Skin, for which means they are able to are called induced pluripotent stem
cells (IPSCs) and can be used in areas
example, is constantly replenished produce numerous cells that are of the body where they are needed,
byskinstemcells. loosely related, such as stem cells in taking on the characteristics of
Stem cells begin their life cyc le as the bone marrow can generate cells nearby cells.
IPSCs are more reliable than stem
generic, featureless cells that don't that make up the blood; he says. "In cells grown from a donated embryo
contain tissue-specific structures, contrast, pluripotent stem cells, because the body is ITl()(e likely to
such as the ability to carry oxygen. found within developing embryos, accept stem cells generated by itself.
IPSCs can treat degenerative
Stem cells become specialised are able to make any one of the conditions such as Parkinson's
through a process called estimated 210 cell types that make disease and baldness, which are
differentiation. This Is triggered by up the human body." caused by cells dying without being
replaced. The IPSCs fill those gaps,
signals inside and outside the cell. This fascinating ability to restoring the body's systems.
lntemal signa Is come from strands transform and divide bas made Professor Fairchild says IPSCs could
of DNA that carry information for a II stem cells a rich source for medical help find a cure for certain disorders:
"By deriving these cells from
cellular structures, while extema I research. Once their true potential individuals with rare conditions, we
signals include chemicals from has been harnessed, they could be are able to model the condition in the
nearby cells. Stem cells can used to treat a huge range of laboratory and investigate the effects
of new drugs on that disease."
replicate many times - known as diseases and disabilities.

022
 Answer:
STRANGE VVhathappensifyou FlatWOI'ms have the ability to (egenefate ofgans.
which is an Invaluable skill fOf' Sllr'Vfvat. Thetefon~.
BUT TRUE halve a flatwor1n? If you cut one in half. Its pluripotent stem cells
activate and create two flatworms. We'd father
A LIFE DIVIDED A It dies B It becomes two flatwonns you didn't try this, though!
C One half lives while the other dies

I•U•Jtl•I!JirW•ll,.!JP Stem cells have been used to restore the sight of patients suffering from certain forms of blindness

How to grow a stem cell

Fertilised human embryos that and put them into a culture dish. divide they are placed into multiple
have been donated for research This is filled with a culture dishes, each trying to complete an
have plenty of stem cells inside medium, which is a mixture of embryonic stem cellline.lfa line is
them as the cells are yet to fully nutrients that encourages the cells completed, it can then be used for
form. Scientists extract the cells to divide and grow. As the ceUs further research and development.

Bone marrow
The bone marrow contains both active cells
and stem cells that are waiting to develop.

__ l

Haematopoietic stem cell

Stem cells Inside the bone marrow are
called haematopoietic stem cells.
Multipotent
This stem cell in an adult
is multipotent, so can
become any blood-
related cell.
Platelets
If you cut yourself, these
blood cells clump together,
stopping the blood flowing
out of your body. Chemical exchange
,....-- When needed, chemicals from
surrounding cells alter DNA
strands inside the stem cell.

Eosinophils and
I Myeloid Lymphoid
neutrophils progenitor cells progenitor cells
These are essential for These are the stem cells These are the stem cells that
stopping infections from that become red blood tum into white blood cells,
spreading in the body. ceUs, among others. responsible for battling disease.

023
 umonsme/1
Olfactory bulb
This area ol the brain is where si!Jlals are
~and smel ispercei\led. Othe<
animals......., a much larger area as they
can pe ceNe wider ra M}bd 511 ds and
use their sense ol smel more.

The ability to smell is one of our

•
most crucial senses and can
influence the food we eat and
the people we date...
Smell, or olfaction to use the proper
terminology, is a very dl reel sense,
in that we actually breathe In
microscopic bits of the
substance that we smell. These hit the
olfactory epithelium, a mucus
membrane in the nasal cavity, which
contains millions of olfactory receptor
neuron cells. Each of these sensory
eel Is is covered in small hal r-llke
structures, called cilla, which react to the
odour and send signa Is to the olfactory nerve,
which relays this information to the braIn so it Is then
perceived as smell. Humans can recognise around
to,ooo different odours and no two Individuals can
sense anything exactly the same.
Olfactory nerves
The oltactory """"" pass
Nasal cavity -~:.::. inlonnation about the particles
This is where air and sensed in the nasal cavity to the
tftaosoopie molecuk!s of brain, where these si!Jlals are
sU>stances we are to smel
ente<. /IJr is p!Aied into this
"""' to pass through into the
Ungs by the body's

_
.... ......._.,_
cjaphragm~

••••• ~ halhowndwlWOit••
Olfactory epithelium +--+-......_~ ~Mr-M.,.-..;;;;
~only·-- This is where the olfactory
neow cells are located. In a
Smell affects taste
2 human. this area is around

-
Ththuman-loacbllllvlho
malnorpnl_ ln_...,. !Ocm squared.
-ra~abucll ... onl)l
-......-. ......
ondsall.~ oiM
1*00..... _ _ _

Cells smell
]==can'
.....,..___ t_
It's • CCNii illCW' rnrth lhlt t61d
The patch ofsensory cells located in the nasal
cavity are made up ofseveral different parts
.........
__ Hotwv«.tNshM
and_ ... _....
M~ --------------------------------~~\
-lholoct. Mucosa lines the epitheiun inside the nasal cavity and catches the
oclol.r particles to be sensed by the receptor lli!U'Oil cells.

At_....,.._.,_
•• ctJ:1::3
.a:~ ....... _~~~~~. Olfactory receptor neli"'O1 eels -----------,

--
sn

5 Saase
·.~....,- ·

of su el
These a r e - - e e l s thatarestinUatedbythe
eiia. They then send .,...._ ll'rough to the brain.

_.,_.. __
ie ..uwes~

----·-
thedi!y

tlwlinttw-.. ...
,_ Olfactory ciia
These sense the particles in <W. There are S.20ol these
-----------tlif\1
on each olfactory ner\1! cell which line the epitheilm.

024
 •• •• •• ••
• • •• ••
Around 2501.> of ~le •• Otl..,.. factors ••• Taste buds are not •• You can lose yoar •• Butterflies taste
STOP 1
are 'supertasters' •• contribute to flavour
•:2 • only on the tongue
:• 3 •
• sense of taste
4 •s
• with their feet

FACTS
TASTE
Things taste different to some
because they are supertasters
and experience taste
signiftcantly more intensely
than 'nOI'TTlal' people.
•
•
tt's not all about just taste buds.

••
•••
Factors such as temperature.
smell and even hearing can
contribute to a thing's flavour
•
•
•
•
•
••
As wt>ll as having around 8,000 :
taste bods on the human
tongue, h~Snans also have
•
•
••
them on the rod of their mooth •
•
tf you happentosuffer a serious
head injury, neurological cisorder •
rx E'\'en dental problems. then
these can severely affect~
ability to taste things property. •
•
•
••
•• Not all species taste things in
the sameWiJY as humans.
Butterlles' taste sensors. for
example. are actually located
in their feet!
alongside taste. and oesophagus.
• •

l•li•Jm1!]1:w.mp The tongue contains obout B,ooo taste buds

Howdo e:$
work?
Discover how we distinguish
between flavours
Taste buds are sensory organs that are found in the little
bumps (or papillae) on the tongue. The tongue contains
about 8,ooo taste buds and they're replaced approximately
every two weeks. Sensitive microscopic hairs on the taste
buds (microvilli) pic!< up dissolved chemicals from food and send
electrical signals to the brain that distinguishes between five different
tastes: sweet, bitter, savoury (umami), salty and sour. Varying
sensitivity to these tastes occurs across the whole of the tongue. But
taste buds alone cannot tell us the exact flavour of food. Other factors
such as smell, spiciness, temperature and texture also contribute to the
eventual taste. So if you hold your nose while you eat then your brain
won't get the full taste story!

"Factors such os smell,

spiciness and texture also
contribute to taste"

five Taste QUalities are found in all areas of

the tongue, although some regjons are
more sensitive than others.
Your taste buds haw
very tiny. sensitive hairs
called miaovili which

n send messages to your

brain about how
something tastes.

Building an in-depth map of the tongue

There is general agreement that humans have five basic tastes,
although the fifth taste 'primary' has only been recently offidally
recognised. Sweetness, bitterness, sourness and saltiness were joined
by savouriness in 2002. Several other sensations that the tongue can
recognise have been identified but are not classified as tastes.
SWeetness is associated primarily with simple carbohydrates-of which sugar is
one of the most common. The way sweetness is detected is complex and only
recently has the current model of multiple binding sites between the receptors
and sweetsubstance itself been proposed and accepted. Asweet taste infers that
the substance is high in energy and studies have shown that newborns in
particular, who need a high calorie intake to grow, demonstrate a preference for
sugar concentrations sweeter than lactose, which is found in breast milk.
Bitterness can be detected in very low levels and is generally perceived to be an
unpleasant or sharp taste. Many toxic substances in nature are known to be bitter
and there is an argument proposed by evolutionary scientists that bitterness
sensitivity is an evolutionary defence mechanism. Humans, however, have now
--
developed various techniques to make previous inedible bitter substances edible
through redudng their toxidty, often through cooking.
The taste of saltiness is produced by the presence of sodium ions, or other
closely related alkali metal ions. Potassium and lithium produce a similar taste as
they are most closely related to sodium.
Sourness detectsaddity. The way we measure the degree of sourness is through •
rating sour substances against dilute hydrochloric. The mechanism involved in
detecting sourness is similar to saltiness in that taste is caused by a concentration
ofions- in this case hydrogen ions. Savouriness is the newest of the recognised
basic tastes and the taste Is produced by fermented or aged foods. Glutamate is a
common compound that can cause this taste and consequently savouriness is
considered fundamental to Eastern cuisine.

025
 umon tonsils explained

What purpose do these fleshy lumps

in the back of our throats serve?

Tonsil
locations
Where you can find
the three pairs of
tonsils in your head

Tonsils are the small masses of

flesh found In pairs at the back of
the throats of many mammals. In
humans the word is actually used
to describe three sets of this spongy lymphatic Palatine tonsils Ungual tonsils Pharyngeal tonsils
tissue: the lingual tonsils, the pharyngeal These are the best·known pair The lingual tonsils are found at These are otherwise known as
of tonsis, as they~e clearly the rear of your tongue -one at the adenoids and are located
tonsils and the more commonly recognised visible at the back of your throal either side in your lower jaw. at the back of the sinuses.
palatine tonsils.
The palatine tonsils are the oval bits that
hang down from either side at the back of your
throat - you can see them Ifyou open your Lots of bed rest, fluids
and pain relief like
Tonsillitis in focus
mouth wide in the mirror. Although the full Tonsillitis is usually caused by certain bacteria
paracetamol are all
purpose of the palatl ne tonsi Is isn't yet recommended for (eg group A beta-haemolytic streptococci) and
understood, because they produce antibodies treating tonsillitis sometimes viral infections that result in a sore
and swollen throat, a fever, white SPOts at the
and because of their prominent position in the back of the throat and diffoculty swallowing.
throat, they're thought to be the first line of Usually rest and a course of antibiotics will see it
defence against potential infection in both the off, but occasionally the infection is very severe
and can potentially cause serious problems, or
respiratory and digestive tracts. reoccurs very frequently. In these cases a
The pharyngeal tonsUsarealso known as the tonsillectomy may be considered - a surgical
adenoids. These are found tucked away in the procedure where the tonsils are removed.
The adenoids are less commonly infected but,
nasal pharynx and serve a similar purpose to when they are, they become inflamed and swell
the palatine tonsils but shrink in adulthood. to obstruct breathing through the nose and
The lingual tonsils are found at the back of interfere with drainage from the sinuses, which
can lead to further infections. In younger people,
the tongue towards the root and, if you poke constant breathing through the mouth can
your tongue right out, you should spot them. stress the facial bones and cause deformities as
These are drained very effidently by mucous they grow, which is why children will sometimes
have their adenoid glands removed.
glands so they very rarely get infected.

026
I•U•JW•1!113N•l!i'i> The vocal cords remain open when you breathe, but dose completely when you hold your breath

, , , ------·~----------~.-r--~
, , ,
,I

'•
I

,,•
,
I

,
I

I'
,
I

I
,
I

The epiglottis stops food

entering the trachea

The vocal cords and larynx in_particular Tongue - - - . 1

have evolved over time to enable humans to This musde, situated in the
mouth, can affect and
produce a dramatic range of sounds in order change sound as it travels uP
from the vocal cords and out
to communicate- but how do they work? through the mouth.

Vocal cords, also known as As al r Is expelled from the lungs, the

----.....J
vocal folds, are situated In
the larynx, which Is placed
at the top of the trachea.
They are layers of mucous membranes
vocal folds vibrate and collide to produce
a range of sounds. Thetypeofsound
emitted Is effected by exactly how the
folds collide, moveandstretchasair
Trachea
The vocal cords are situated
at the top of the lr.IC'-
wNch is where air from the
kNlgs traYels uP through
I
that stretch across the larynx and control passes over them. An individual from the chest.
how air is expelled from the lungs In 'fundamental frequency' (their standard
order to make certain sounds. The pitch) Is determined by the length. size Vocal cords -----!......_-..-..~.
These layers of I1'AICOUS
primary usage of vocal cords within and tension of their vocal cords.
merrb a.es stretch acaoss
humans is to communicate and It Is Movement of the vocal folds is controUed the larynx and they open,
hypothesised that human vocal cords by the vagus nerve, and sound is then dose and vibrate 10 produce , ,
actually developed to the extent we see further fine-tuned to form words and ,,
,,
dille ent sounds.
now to facilitate advanced levels of sounds that we can recognise by the
communication In response to the larynx, tongue and lips. Fundamental I
I
formation of social groupings during frequency in malesaveragesat 125Hz. I
I
phases of primate, and specifically andatztoHzin females. Children have a I
I
human, evolution. higher average pitch at around 300Hz. I
I
I

t
I

male Epiglottis ---...!L..---'~•1

i
I
This is a flap of skln that 1
shuts off the trachea when 1
Male voices are often much lower than voices has been studied In relation to I
an individual is swallowing
female voices. This is primarily due to sexual success, and individuals with food. It steps food and liquids Vocal cords open when
the dllfe.rent size of voca Ifolds present lower voices have been seen to be 'going down the wrong way'.
breathing. but are pulled
.--~ together when speaking
in each sex, with males having larger more successful in reproduction. The
folds that create a lower pitched sound, reason proposed for this is that a tower Oesophagus _ _..
and females havingsmaller folds that tone voice may Indicate a higher level This tube, situated ~nd
create a higher pitch sound. The of testosterone present In a male. the lr.IC'- is where
average size for male vocal cords are food and liquid traYels
between 17 and 25mm, a nd females down to the slomad1.

are normally between 12.5and 17.5mm.

From the range In size, however. males ~ --------~~--~
can be seen to have quite high pitch ~are essential for the

voices, and females can have quite low production of Sl>«'ific

S<U1ds, like 'b' C< '))'.
pitch voices.
The other major biological
difference that effects pitch Is that ~~ ------~~_.
Known as the IIOice
males generally have a larger voca I box, this protects the trachea
tract, which can further lower the tone and is heavly ir1IIOived In
of their voice Independent of vocal contn>&lg pitch and vOOme.
cord size. The pitch and tone of male The weal cords are situated
within the larynx.

027
 most fascinating organ of oil

The human brain is the most

mysterious- and complex-
entity in the known universe
It's a computer, a thinking machine, a pink organ, and avast
collection of neurons- but how does It work? The human brain is
amazingly complex-in fact. more complex lhananythlnginthe
known universe. The brain effortlessly consumes power, stores
memories, processes thoughts, and reacts to danger.
In some ways, the human brain isllkea car engine. Thefuel- whlchcould
be the sandwich you had for lunch or a sugar doughnut for breakfast - causes
neurons to lire Ina logical sequence and to bond with other neurons. This
combination of neurons occurs incredibly fast, but the chain reaction might
help you compose a symphony or recall entire passages of a book, help you
pedal a bike or write an email to a friend.
Sdentists are just beglnni ng to understand how these brain
neurons work -they have not figured out how they trigger a reaction
when you touch a hot stove, for example, or why you can re-generate
brain cells when you work out at the gym.
The connections Inside a braIn are very si mliar to the Internet- the
connecllonsareconstantlyexchanging information. Yet, even the internet
is rather simplistic when compared to neurons. There are ten to 10oneurons,
and each one mal<es thousands of connections. This is how the brain
processes information, or determines how to move an arm and grip a surface.
These calculations, perceptions, memories, and reactions occur almost
instantaneously, and not just a few times per minute, but millions. According
to jim Olds, research director with George Mason University, if the internet
were as complex as our solar system. then the brain would be as complex as
our galaxy. In other words, we have a lot to learn. Sdence has not given up
trying. and has made recentdiscoveriesabout how we adapt, learn new
information, and can actually Increase brain capability.
In the most basic sense, our brain is the centre of all input and outputs in the
human body. Dr Paula Tallai,a co-director of neuroscience at Rutgers
University, says the brain Is constantly processing sensory information- even
from infancy. "It's easiest to think of the brain in terms oflnputsand outputs;
says Tallal. "Inputs are sensory information, outputs are how our brain
organises that information and controls our motor systems.·
Tallal says one of the primary functions of the brain is in learning to predict
what comes nexL In her research for Scientific Learning, she has found that
young children enjoy having the same book read to them again and again
because that is how the brain registers acoustic cues that form into phonemes
(soundsl to become spoken words.
·we learn to put things together so that they become smooth sequences;
she says. These smooth sequences are observable in the brain, interpreting

028
 Spennwhale Mouse lemur Elephant
The sperm whale has The s mallest pr'imate At 10.5 poonds
evolved the largest brain brain is owned by the (4.78kg) it'scertalnlya
ever to exist on our pygmy mouse lem.~r of big one. The b<aln of
plane~ w<!igling as Madagascar and the elephant makes up
much as nine kilogr'CIO"'s weighs in a t just 0 .004 1~ than 0.1 per cent of

Of 20 pot.lldS. pounds(2g). Its body w<!lght.

ltU•JU•11J!3N•IW The overage human brain is 14omm wide x 167mm long x 93mm high
, - - - - Cerebral cortex
The 'grey matter' of the brain cootrols
cognition, motor activity, sensation, and
other higher level functions. Includes
the association areas which help
Functions of
process infO<mation. These
association areas are what
distinguishes the ho.man
brain from other brains.
cerebral
Frontal lobe
The cerebral cortex is the wrinkling
Primarfy oontrols senses
suc:ll as taste, hearing, and
part of our brain that shows up when
smell Association areas you see pictures of the brain
might help usdetennine
langu- and tt-e tone ci
~ex
movements l
~--=··--· ~
solving \
------ ' SN!Ietal""""'"'""'
. - - - - Parietal lobe
Where the brain senses
touch and anytling that
interacts with the surface
of the skin, makes us
aware of the feeings
dour body and
where we""'
in space.

Prefrontal cortex 1 - - - - - - -Temporallobe

Executive functions such as COft'1:llex. What cistinglishes the t.Jman
plannilg, memorising. social and verbal brain ... the abiity to process
skils, and anytting that requires and interpret what other parts
ad\tanoed Uinking and interactions. tn Analysis of of the brain are hearing,
L___ _ _ sounds
adults, helps us deteNrine whether an sensing, or tasting and
action makes sense or is dangerous. determine a response.

"In a sense, the main function of

the brain is in ordering information
- interpreting the outs1oe world and
making sense of it"
the outside world and maldngsense of it. The brain them (or even faster in some cases). This means
is actually a series of interconnected that when you reach out to open a door, your
'superhighways' or pathways that move 'data' from brain has already predetermined how to move
one part of the body to another. your elbow and clasp your hand around the door
Tallal says anotherway to think about the brain handle - maybe even simulated this movement
is by lower and upper areas. The spinal cord moves more than once. before you even actually perform
information up to the brain stem, then up into the the action.
cerebral cortex which controls thoughts and Another interesting aspect to the brain is that
memories. Interestingly, the brain really does work there are some voluntary movements and some
like a powerful computer in determining not only involuntary. Some sections of the brain might
movements but registering memories that can be control a voluntary movement - such as patting
quickly recalled. your knee to a beat. Another section controls
According to Dr Robert Melillo, a neurologist involuntary movements, such as the gait of your
and the founder of the Brain Balance Centers walk - which is passed down from your parents.
(www.brainbalancecenters.com), the brain Reflexes, long-term memories, the pain reflex -
actual ly predetermines actions and calculates the theseareall aspects that are controlled by sections
results about a half-second before performing in the brain.

029
 Neurons, nerves and the spinal cord
-------------------------------------
Naron
A net.I'OO is a l'lei'"Ye ceiiW1
the bran that C<W1 be
activated (l.ISUaly by
glucose) to COIOIOCt with
netronS and form a •
I
-
bond that trigger-s an
action in the brain.

Neu-otransmitter
~r-:-- A neurotransmitter is the
Neurons fire like electrical circuits
• electnH:hemical cn:u~
that carries the signal from Neurons area kind of cell In the brain (humans have many cells in
one neuron to another
the body, Including fat cells, kidney cells, and gland cells). Aneuron
along the axon.
is essentially like a hub that works with nearby neurons to generate
.-- A thin synapse an electrical and chemica Icharge. Dr likosky of the Swedish
A thin synapse Medical Inslltute says another way of thinking about neurons is
(measuring just a few that they are lil<e a basl<etball and the connections (called axons)
nanometres) between are lll<e electrlca Iwires that connect to otherneurons. This creates
the neurotransmitter,
carried aklng the axon in
a kind of circuit In the human body. Tallal explained that input
the brain, forms the
from the five senses In the body cause neurons to fire.
electro-chemical "The more often a collection of neurons are stimulated together
CO<Olection. In lime, the more likely they are to bind together and the easier and
easier it becomes for that pattern of neurons to lire in synchrony as
well as sequentially; saysTallal.

Brain
TrackVis generates unique maps of the brain
TrackVis is a free program used by neurologists to see a map of the brain that shows
the fibre connections. On every brain, these neural pathways help connect one part of
the brain to another so that a feeling you experience In one part of the brain can be
transmitted and processed by another part of the brain (one that may dectde the touch
is harmful or pleasant). TrackVis uses fM Rl readings on actual patients to generate the
colourful and eye-catching Images. To construct the maps, the program can take
"The brain - a fragile several hours to determine exactly how the fibres are positioning in the brain.

organ that weighs •

about 1,500 grams"

brain ....
•
-
you could hold it
If in your hand...
In pictures, the human brain often looksplnkand spongyz
U.COiiiJ 2 . . . . ...,
III!I'EI
1

11. . . . . .•. . . . . 11~­

•. . . . .
- --.
According to Dr Wllliam Ukosky, a neurologist at the Swedish
Medical Institute (www.swedlsh.org),the brain Is actually
quite different from what most people think. Llkosky __... . .
lllilp5h~--­
I,CIOO,..aoHcs pox m
tlllll ...... tau • I tit
7

- -••-
described thebrainasbelng not unlike fetacheeseln
appearance-a fragile organ that weighsaboult,5Q()grams
andsagsalmostlikea bag filled with water. In the skull, the
brain Is highly protected and has hard dssue, but most of the -- -- - •-
fatty tissue in the brain-which helps pass chemicals and
other substances through membranes-Is considerably --·
"- - -
-.,. ............•
.........
._,.. ..,
_
more delicate.

030
 • • • •
••
•
••
•• The brain consists
•
•
• •••
STOP 1
100,000 miles of
blocid vessels
•• Headache not
•
. thebr.....
• Ill
2
. I) •
•• of60%t.rt
3
• Your brain uses :ZOO!c>
•• of power
:4
•
•• The brain has trillions
•
•• s
• of c:onnections

FACTS There are a staggering

lOO,OOOmHesofblood
...essels in the brain, that is
enough to wrap around
!
•
•
•
•••
A headache actualyOCOJrs
in blood vessels around the
blain. not around the brai'l
itself. The brain cannot feel any
•
•
•
••
•
•• Your brain is 60 per cent fat
-which helps canywater and
protein t hrough membranes to
brain ceUs. keeping everything
:
•
•
•
The brain is ~ite ~eedy; it
uses about 20 per- cent of the
power in your body that is
generated from food
•
••
••
The brain has trillions of
oonnections .. much
more than the internet,
and more than can
THE BRAIN Earth four times. • pain whatsoever. • ticking over.
•
• co~tionand prooessklg. •
• ounendy be counted

ltU•JU•11J!3N•IW The adult human brain weighs about 1.4kg [or three pounds)

Nerve transmissions - - - - - - - - - -+ Nerve triggers

How do Some """"' transmiss<ons trawl great

distances through the human body,
others lriM!I short distances - both use
a de-polarisation to create the circuit. • • • •
When m any neli'OI1s are activated together
at the same time, the nerve is excited - this
is when we might feel the sensation of
touch or a distinct smel.
De-polarisation is like a wound-._., •
• •
spring that releases stored energy oooe • • • •
it is triggered.

work? Myelinated and -

•

• •• •• • • •
•
•
•
•
.. • •• •
• •
••••
.••....
. . -.
•
Nerves carry signals throughout the un-mylinated - - -•
•
•
•
•
•
• •
•
• •• • • • • ••
•
• •
body- a chemical superhighway Some nerves are fTIY"linated
(or insulated) with fatty tissue
• • • •• • •
• • • ••
•
•
•
•

Nerves are the transmission cables that carry brain waves in the
human body, says Sol Diamond, an assistant professor at the Thayer
that appea<s white and forms a
slower connection over a
longer distance. Others are
• • •
• •
• •
• •
•
- •. • •
•
•
•
•
•
• •

School of Engineering at Dartmouth. According to Diamond, nerves un-myelinated and are

communicate these signals from one point to another, whether from un-insulated. These nerves
your toenail up to your brain or from the side of your head. tr.M!I shorter distances.

•
sp Spinal cord core
The spinal cord actually In the core of the spinal cord, grey matter

is part of the brain and - fike the kind in the outer layer of the
brain - is for processing nerve cells such

plays a major role as touch, pain and m ovement

Scientists have known for the

past 100 years or so that the
spinal cord is actually part of
the brain. According to
Melillo, while the brain has
grey matter on the outside
(protected by the skull)and
protected white matter on
the inside, the spina l cord is
the reverse: the grey matter is
inside the spinal cord and the
white matter is outside.

- - - - - - Nell'ogenesis
Grey matter cells According to Tallal, by repeating brain
Grey matter eels in the spinal oord activities such as memorisation and
camot regenerate, w hich is why pattern recognitioo, you can grcwv nevv
people w ith a serious spilal cord injury brain cells in the spinal cord and brai"t
cannot recover over a period of time.
White matter cells can re-generate.

White matter cells ==------:;T;.....-:::;;;;;'T---'

White m atter oells in the spinal cord
carry the electro-chem ical pulses up to ;....._ _ _ _ _ _ _ _ Neuroplasticity
the brain. For exam ple, when you are
kicl<ed in the shin, you feel the pain in In the spinal oord and in the brain, cells
the shin and your brain then tells you can rejuvenate over tWne when you
to m ove your hand to aN~ that area. exe.-cise and become strengthened. This
process is cal~ neuroplasticity.

031
 Inside the human eye

Fovea
This pit at the centre of the
back of the eye is rich in light
receptors and is responsible
for sharp central vi.slon.

Optic nerve
Uncovering one of the most complex Signals from the retina
travel to the brain via the

constructs in the natural world optic nerve, a bundle of

fibres that exits through
the back of the eye.
The structure of the human eye is so of the pupil. The light first passes
complex that It's hard to believe that th rough a tough protective sheet
it's not the product of intelligent called the cornea, and then moves into
design, but by looking at the eyes of the lens. This adjustable structure
other animals, scientists have shown that it bends the light, focusing it down to a
evolved very gradually from a simple light-dark point on the retina, at the back of the eye.
sensor over the course of around 100 million The retina is covered In millions of
years. II functions in a very similar way to a light-sensitive receptors known as rods
camera, with an opening through which the and cones. Each receptor contains
light enters, a lens forfocusingand a light- pigment molecules, which change
sensitive membrane at the back. shape when they are hit by light,
The amount of light that enters the eye is triggering an electrical message
controlled by the circular and radial muscles in tllat travels to the brain via the
the iris, which contract and relax toalterthesize optic nerve.

Seeing in three dimensions

Each eye sees a slightly different image, allowing t he brain to perceive depth
Our eyes are only able to produce two-dimensional images, but with some clever
processing, the brain Is able to build these Rat pictures into a three-dimensional
view. Our eyes are positioned about five centimetres (two inches) apart, so each sees
the world from a slightly different angle. The brain compares the two pictures,
using the dmerences to create the illusion of depth.

Individual image
Due to the positioning of our eyes,
when objects are closer than about
5.5m (18ft) away, each eye sees a
slightly different angle.

Comb ined image

The incoming signals from both

··.~ eyes are compared in the brain, and

the subUe differences are used to
create a three-dimensional image.

Retina Iris
Try it for yourself The retina is covered in This circular rnusde
By holding your hand in front of receptors that detect light. controls the si2e of
your tace and dosing one eye at a It is highly pigmented, the pupil, allowing it
time, it is easy to see the different preventing the light from to be closed down in
20 views perceived by each eye. scattering and ensuring a bright light, or opened
crisp image. wide in the dark.

032
 2.BIGGER

~~~82
Tarsier Ostrich Colossal squid
The eyes of these tiny Ostriches are the largest Uttle is known about
primates are as big as IMng birds and also have these mysterious
the.k btains, so as a the largest eyes of any creatur'~, but they have
result, they have living land animal, eyes the size of Footballs
AN EYE FOR SIZE developed extremely measuring an l.nc:redible - tOO largest knoWn in the
good night vision. ..__ _......;"-_.._ _ __.. Scm (21n) In dlamet..-. animal ldngdom.

[t!f•1\1!I!J!3~[•1~!l? 285 million people in the world ore estimated to be visually impaired and 39 million of them ore blind

. - - - - - - - - - - Ciliary body
This tissue surrounds the
Vision problems
lens and contains the The most common problems
muscles responsible for with our eyesight
changing its shape. Farsightedness (hyperopia)
lf the eye is too short, the cornea is too flat, or if
the lens sits too far bad<, incoming light is
focused behind the retina, making nearby
objects appear blurry, particularly in the dark.

- - - Sclera
A tough white membrane
known as the sclera helps
to maintain the eye's
spherical shape.
Nearsightedness (myopia)
lf the eye is too long, or the cornea and lens are
too curved, the light is focused before it hits
the back of the eye, and then starts to defocus
again as it reaches the retina, making distant
objects difficult to see.

Colour-blindness
This rare condition is often linked to a gene on
the X-chromosome and occurs more commonly
in men than in women. A defect in the cone
cells of the eye reduces the number of colours
that can be detected.

Protection
The eyes are shielded by several layers of protection.
They are almost complet ely encased in bone at the
back and insulated from shock by layers of muscle
and connective t issue. The front is kept moist with
tears and constantly w iped by the eyelids, while the
hairs of the eyebrows and eyelashes cat ch any debris
that might fall in.

Lachrymal gland
Tears are produced here
and wash across to the
inner corner of the eye,
helping to clean and
nourish the surface.

Comea
The pupil and iris are Eyelashes
Lens covered in a tough, Eyebrows Eyelashes not only catch
The lens is responsible for transparent The arch of the eyebrows dust before it enters the
focusing the light, and can Pupil membrane, which helps to keep sweat and eye, they are also sensitive,
change shape to The pupil is a hole that provides protection rain away from the eyes, like whiskers, and the
accommodate objects allows light to reach and contributes to channelling it down the slightest unexpected touch
near and far from the eye. the back of the eye. focusing the light. sides of the face. triggers a protective blink.
•
033
 Ears explained

The human ear performs a

range of functions, sending
messages to the brain when a
sound is made while also
providing your body with a
sense of balance
Thethingtorememberwhenleamlng
about the human earls that sound Is all
about movement. When someone
speaksorbangsadrumormakesany
kind of movement. the air around them Is
disturbed, creating a sound wave of alternating
high and low frequency. These waves are detected
by the ear and interpreted by the bralnaswords,
tunes or sounds.
Consisting of air-filled cavities, labyrinthine
fluid-filled channels and highly sensitive cells, the
ear has external, middle and Internal parts. The
outer ear consists of a skin-covered flexible cartilage
flap called the ·auricle', or'plnna'. This feature Is
shaped to gather sound waves and amplify them
before they enter the ear for processing and
transmission to the brain. The first thing a sound
wave entering the ear encounters is the sheet of
tightly pulled tissue separating the outer and
middle ear. This tissue Is the eardrum, or tympanic
membrane, and itvlbratesassound waves hit it.
Beyond the eardrum, in the air-filled cavity of the
middle ear, are three tiny bones called the 'ossicles'.
These are the smallest bones In your enUre body.
Sound vibrations hitting the eardrum pass to the
first ossicle, the malleus(hammer). Next the waves
proceed along the incus(anvll) and then on to the
(stapes) stirrup. The stirrup pressesagalnsta thin
layer of tissue called the 'oval window', and this
membrane enables sound waves to enter the
fluid-filled inner ear.
The inner ear is home to the cochlea, which
consists of watery ducts that channel the vibrations,
as ripples, along the cochlea's spiraling tubes.
Running through the middle of the cochlea Is the
organ of Corti, which is lined with minute sensory
hair cells that pick upon the vibrations and
generate nerve impulses thataresentto the brain as
electrical signals. The brain can Interpret these
signals as sounds.

034
 • •• •• •
• •
• • • •
•• Underwater hearing • Hearing loss •• Wax essential •• Making me dizzy
STOP
Hearing range
1 H...-nan ears can hear sounds :2
•
•
Hl.ma"'s can hear much
hir;tler-pitched sounds
•
•
•
•
• 3 The most common causes of
hearing loss are ageflg and
•
•
•
•
4 Waxdeansandh.Jbrieatesthe
••
•• sInflammation of the imer ear due

FACTS
with frequencies between 20Hz outer auditory canal, to viraVbacterial conditions such as
and 20.000Hz. The abi~ty to hear
• (200.000Hz) when under water. •• noise.. As we age. our abHity to •• transportilg dirt and dead •
•
•••
labyri'lthitis can cause dizziness
frequencies above and below ttis • because we can 'hear' w ith our •
• heat souOOs with h;ghe< •• skin away from the ear. tf and nausea. When balance is
•• •• ••
is linked to the size of the cells •• bones. bypassing the outer ear frequencies deteriorates- this is : exc.es.sive wax is a problem, affected, sufferers may rot be able
HUMAN EARS and sensitivity. and ossides. • known as 'presbycusis'. • consult )'CIII doctor. • to walk or stand.
• • • •

ltU•JU•11J!3N•IW The eardrum needs to move less than the diameter of o hydrogen atom in order for us to perceive sound

A bony snail-shaped structure,

Thevesti
Inside the inner ear are the vestibule
rsystem
the cochlea receives vibrations
from the ossicles and and semicircular canals, which
feature sensory cells. From the Semicircularcanal
These three loops positiooed
semicircular canals and at right angles to each other
maculae, information about are fuD of fluid that transports
which way the head is sound vibrations to the crista.
moving is passed to
receptors, which send
electrical signals ,......- Vestibular nerve
Sends infonnation
to the brain as about equilibrium from
nerve impulses. the semicircular canals
to the brain.

Macula::-.S~~~~~~d'f-~¢~
Asensayarea ~~l-~t::=:==:~~--~~ Vestibwe
~ in Inside the fluid-filled
tiny hairs. vestibules are two
chambers (the utricle
and saccule), both of
which contain a
C~a --------------------------~ structure called a
At the e nd of each semicircular canal macula, which is
there are tiny hair-filled sensory receptors covered in sensory
called aistae. hair cells.

A sense of balance
The vestibular system functions to give detect acceleration lie, movement ofyour
you a sense of which way your head Is head) in three different directions due to
pointing in relation to gravity. It enables the positioning of the loops along
you to discern whether your head is different planes. Like the organ of Corti,
upright or not, as well as helping you to the semicircular canals employ tiny hair
maintain eye contact with stationary cells to sense movement The canals are
objects while your head is turning. connected to the auditory nerve at the
Also located within the inner ear, but back of the brain.
less to do with sound and more Your sense of balance is so complex
concerned with the movement of your that the area of your brain that's
head, are the semicircular canals. Again dedicated to this one role involves the
filled with fluid, these looping ducts act same number of cells as the rest of your
like internalaccelerometers that can brain cells put together.

035
 our teeth
The biological
structures that are so
versatile they enable us
to eat a well varied diet

1be b"Ollble
with
.,..
~"'
The primary function of
teeth Is to crunch and chew
food. For this reason, teeth
• are made of strong
the teeth firstappearatslx months old
and are replaced by secondary teeth after
sixorsevenyears.Someanlmalsdevelop
only one set of teeth, while sharks, for
From ancient times healers have sought
to treat and replace the teeth with false
ones. Examples of this pmctice can be
seen from ancient Egyptian times and
Tooth decay, also often substances -namelycalcium, instance, grow a new set of teeth every today, we see revolutionary new
known as dental caries, phosphorus and various mineral salts. two weeks. techniques in the form of dental
affects the enamel and The main structure of the tooth Is With humans, tooth loss can occur Implants, whicharesecureddeepwithin
dentine of a tooth, breaking dentine, this itsell Is enclosed in a shiny through accident, gum disease or old age. the bone of the jaw.
down tissue and creating substance called enamel. This strong
fissures in the enamel. '!Wo whltecoatingls the hardest material
found In the human body.
Enamel - - -..... , - - - - - Pulp
typesofbacterla-namely The pulp nouislles the
Humans have different types of teeth The white, outer s<rlace ""
Streptococcus mutansand of the tooth. This can be dentine and keeps the
Lactobacillus-are that function In various ways. Incisors dearly seen when tooth healthy - the pulp is
responsible for tooth decay. tear at food, such as the residue found looking in the mouth. the soft tissue of the tooth,
Tooth decay occurs after on bones, while bicuspids have long which is protected by the
repeated contact with acid· sharp structures that are also used for dentine and enamel.
producing bacteria. ripping. Bicuspids tear and crush while
Environmental factors also molars, which have a flatter surface, Cementum --...,...;;P!II(
have a strong effect on dental grind the food before swallowing. This The root coating, k
protects the root
health. Sucrose, fructose and aids digestion. Because humans have a
canal and the
glucose create large problems varied army of teeth (called collective nerves. tt is
within the mouth, and diet dentition) we are able to eat a complex coronected to the
can be an important factor In dlet of both meat and vegetables. Other jav.boc "' throujl
maintaining good oral health. species, suchasgrazlnganimals, have collagen fibres.
The mouth contains an specific types of teeth. Cows, for example,
enormous variety of bacteria, have large fiat teeth, which restricts them
which collects around the to a simple diet. Blood vessels
teeth and gums. This Is visible Teeth have many functions, in some and nerves --_..:...~~T-~ Bone
in the form of a sticky white cases they aid hunting but they also have The blood........ts The bone acts
substance called plaque. strong psychological connotations. Both and ner wescany as an
Plaque Is known as a bio!Um. animals and humans bare their teeth mxxtat i1111pcw ta It
llOlWislwnent to the anchor lor the
After eating, the bacteria In when faced with an aggressive situation.
tooth and ...., tooth and
the mouth metabollses sugar, Teeth are the most enduring features of keeps the root
sensi!Neto
which subsequently attacks the human body. Mammals are pre5Slftand 5eCU'e witiW1
the areas around the teeth. described as 'diphyodont', which means ~ the jawbone.
they develop two sets of teeth. In humans

036
 1. Hippopotamus 2. Piranha 3. Hamster
A hippopotamus has an Piranha teeth are very sl'l'\2lll A membet of the rodent family,
eoor'mous mouth that can but can be extr'emely shar'p and the hamster has teeth that
toeasur'e up to 1.2 meues ate often used by the local grow continuously. They
wide. They are equipped with populations of South America lher'efore need to 9rind thelt
a pair of huge and ve.ry to create a vatiety of tools teeth on a har'd substance to
dangerous inclsots. and weapons. prevent overgr'owth.

ltU•JU•11J!3N•IW The ancient Egyptians hod severe problems with their teeth. They invented the world's first dental bridge

Maxilla
Alayout of the upperarea
ofyour mouth

The upper and lower areas of the mouth

are known as the maxilla and the
mandible. The upper area of the mouth
isattachedtotheskull boneandisoften
called the upper arch of the mouth,
while the mandible is the v-shaped bone
that carries the lower set of teeth.

Camnete&h ----------------~ canine

long, pointed teeth that are
used for holding and tearing at
the food within the mouth.

Wisdom teeth - - - - - - - - - - - - -
Usually appear between the
ages of 17 and 25, and often
erupt in a group of four.

of
The approximate
ages at which the
permanent teeth
begin to erupt
Age&
First molar
Age7
Central incisor
The tooth is a complex structure. The Age9
enamel at the surface of the tooth is highly First premolar
visible while the dentine is a hard but
porous tissue found under the enameL
The gums provide a secure hold for the AgelO
tooth, while the root is anchored right Second premolar
into the jawbone. In the centre of the tooth
there is a substance called 'pulp' which Agell
contains nerves and blood vessels, the
pulp nourishes the dentine and keeps the Canine
tooth healthy.
Tooth formation begins before birth. Age12
Normally there are 20 primary teeth
jhuman baby teeth) and later, 28 to 32 Second molar
permanent teeth, which includes the
wisdom teeth. Of the primary teeth, ten
are found in the maxilla jthe upperjaw)
Mandible First and second
premolar te&h
Age17to21
or not at all
Alook inside your towerjawbone
and ten in the mandible jlower jaw), while
the mature adult has 16 permanent teeth Lateral and central incisors _ _ _ _ _.....
The premolar or bicuspids are
located between the canine
Third molar
in the maxilla and 16 in the mandible. Incisor comes from the latin V'JOrd 'to and molar teeth. They are (wisdom teeth)
cut', they are used to grip and bite. used for chewing.

037
 eckonotomy

a to enec
Explore one of the most complex and functional areas of the human body
The human neck is a perfect blend
of form and function. It has several
Get it in the neck Larynx
This serves two rna.il
We show the major features that are pack ed
specific tasks (eg making it possible into this junction between the head and torso functions: to connect tile
to turn our heads to seeI, while Oesophagus mouth to tile trachea, and
This pipe comects the to generate your voice.
serving as a conduit for other vital activities (eg Sympathetic trunk Cartilage ---.. mouth to the stomach,
connecting the mouth to the lungsj. These special nerves run This tough tissue and is collapsed llltil
The anatomical design of the neck would alongs<de tile spinal cord, and protects tile delicate youswalow Carotid artery
control svveatalg, heart rate airways behind, sOf'I"K?thing, when its These arteries transmit
impress modern engineers. The flexibility of and breathing, among other including the larynx. muscular walls stretch. oxygenated blood from
the cervical spine allows your head to rotate, vital functioos. tile heart to the brain.
There are two of them
flex and tilt many thousands of times a day.
Vertebra - - - " " " Cri!:lrt and left), i1 case one
The muscles and bones provide the stre ngth These bones provide becomes blocked.
Phrenic nerve
and flexibility required, however the really These important SlJilpoft to p.......,rn tile neck

impressive design comes with the trac hea, nerves come off the collapsi"lg, hold"" tile skul
third, fourth and fifth and protect the spinal
oesophagus, spinal cord, myriad nerves and cord within.
neck wrtebrae, and
the vital blood vessels. These structures must innervate tile
all find space and function perfectly at the same ~whidl
keeps- breathing
time. They must also be able to maintain their
(without - havi1g to
shape while the neck moves. think about it).
These structures are all highly adapted to
achieve their aims. The trachea is protected by
a ring of strong cartilage so It doesn't collapse,
while a llowing enough flexibility to move when
stretched. Above this, the larynx lets air move
over the vocal cords so we can speak.l'arther
back, the oesophagus is a muscular tube which
food and drink pass through en route to the
stomach. Within the supporting bones of the
neck sits the s pinal cord, which transmits the
vital nerves allowing us to move and feel. The
carotid arteries and jugular veins, meanwhile,
constantly carry blood to and from the bra in.

How does the head

connect to the neck?
They are connected at the bottom of the skull
and at the top of the spinal column. The first
vertebra is called the atlas and the second is
called the axis. Together these form a special
pivot joint that grants far more movement than
other vertebrae. The axis contains a bony
projection upwards, upon which the atlas
rotates, allowing the head to tum. The skull sits
on top of slightly flattened areas of the atlas,
providing a safe platform for it to stabilise on,
and allowing for nodding motions. These bony
connections are reinforced with strong muscles,
adding further stability. Don' t forget that this Spinal cord _ _ _ _ __..;;;
amazing anatomical design still allows the vital
Shielded by thewrtebrae.
spinal cord to pass out of the brain. The cord sits
in the middle of the bony vertebrae, where it is the spinal cord sends
molD< sq,als daMl nerves
protected from bumps and knocks. It sends out
and receives sensory
nerves at every level (starting right from the top)
i"lforrnalion from all
granting control over most of the body.
around the body.

038
 2.LONGER Giraffe
The giraffe has the
longest oeck ol any land
animal today. However,
amazingly, it has the same
nurrber of neck vertebrae
as~ do- seven.

l.U•Jt(•l!-rW•mG> The hyoid bone at the front of the neck is the only one 1n the body not connected to another bone

Just say no...

The physiology that lets
us shake our heads

.-J---~Th
:-'is~
The """""""' of articulates (ma..oes)
the atlas around around the odontoid
the odontoid P"9 process which
allows for rotation projects through iL
of the skull alxM! it.

Odontoid - - ~~---- Axis

process In the spinal column, this
This bony projection is the second vertebra,
is parallel with the which provides the
longitudinal axis stability for the required
of the spine. upwards bony projection.

Sternocleidomastoid
Tum )'OU' head left and feel the Atlas
right of )'OU' neck - this is the The first neck (cervical)
muscle doing the turr*>g. vertelra is what
pem its the nodding
motion of the head

Trapezius
When you shrug )'0\1'
shoUders this !woad
muscle !e<ISeS up
between )'0\1'
Axis shoulder and neck.
The second c:eMcal
vertebra alows rotation
of the head. So when
you're shaking )'OU' head
to say no, you hiM! got
this bone to thank.
Cervical plexus
'--- Jugular vein These nerves provide
These ~~esse4s sensation to the skin and
drain blood also control the fine
from the neck,
ret:uming it to
the heM.

Vertebrae create a
cage of bones to
protect the critical
spN cord withh

Seventh cervical
vertebra
This is the bony Splenius capitis
~at the This rnJSde is an exa11 !pie
bottoo I of )'0\1' neck, ofoneofthemany
whch you can feel; strap.Jiloe rniSdes which
doctors use it as a ldnd of COilbol the mUtitudeof
landmark so they can fine l1'lOIIerTiel1! of the
locate the other vertebrae. head and neck.
 human skeleton
Collarbone ---....,
Scapula

Without a skeleton, we would not

be able to live. It is what gives us
our shape and structure and its
presence allows us to operate
on a daily basis. It also is a
fascinating evolutionary link
to all other living and Carpals
extinct vertebrates
The human skeleton Is crucial
for us to live. It keepsourshape 4. Radius/Ulna - - - - --1
and muscle attached to the The racius a1d .ma are the bones
situated in the forearm. They
skeleton allows us the ability to
connect the wrist and the elbow.
move around, while also protecting crucial
organs that we need to survive. Bones also
produce blood cells within bone marrow
and store minerals we need released on a 5. Ribcage - - - - - - - - - - . - J
daily basis. This stru<:tJ.n of many single rib bones creates a
protective barrier for organs situated in the chest
As a fully grown adult you will have
cavity. They join to the vertebrae in the spine at the
around2o6 bones, but you are born with back of the body, and the sternum at the front
over 270, which continue to grow,
strengthen and fuse after birth until
around 18 in females and 20 In males. makes up bone, osseous tissue, is
Human skeletons actual ty do vary between actually mineralised calcium
sexes in structure also. One of the most phosphate, but other forms of tissue such
obvious areas is the pelvis as a female must as marrow, cartilage and blood vessels are
be able to give binh, and therefore hips are also contained In the overall srructure.
comparatively shallower and wider. The Many individuals think that bones are
cranium also becomes more robust In solid, but actually inner bone is porous and
males due to heavy muscleattachmentand full ofllttle holes.
a male's chin Is often more promin.ent. As we age, so do our bones. Even though
Femaleskeletons are generally more cells are constantly being replaced, and
delicate overall. However, although there therefore no cell in our body is more than
are several methods, sexing can be difficult 20 years old,they are not replaced with
becauseofthe level ofvariatlonwe see perfect, brand-new cells. The cells contain
within the species. errors in their DNA and ultimately our
Bones are made up of various different bones therefore weaken as we age.
elements. In utero, the skeleton takes Conditions such as arthritis and
shape as cartilage, which then starts to osteoporosis can often be caused by ageing
calcify and develop durlnggestatlonand andcauseissueswithweakeningofbones
following birth. The primary element that and reduced movement ability.

040
 1. Snails 2.Snake 3.Giraffe
HEAD2 Exoskeletons are often The skeleton of a snake Consideting the size of a

HEAD seen in animals. These <l(e

bulky, tough outer layer'S
that fli'Otect the in<ivlrual,
is one of the s trangest.
Because of how it moves,
lt has more joints in the
fjraffe's neck. you'd expect
it to have more cetVical
vertebrae than a human,
Instead of the body, prlmaflly ll<!rtebrae. but It only has seven - the
SKELETONS endoskeletons we have. and has no Hmlls. same as~

ltU•JU•11J!3N•IW Around five per cent of o/1 onimols hove backbones and ore therefore classified as vertebrates

Inside our
skeleton ilow our joints work
The types of joints 1n our body explained
How the human
skeleton works ond 1. Ball and socket joints 3. Skull sutures
Both the hip and the shoulder joints are Although not generally
keeps us upright
Whether it's a complete break or ball and socket joints. The femur and
humerus have ball shaped endings, which
thought of as a 'joint', all the
cranial sutures present from
!.Cranium just a fracture, botfi can take time tum in a cavity to aUow mOl/em""" w here bones have fused in
The cranium, also known as to heal properly childhood are in fact
immoveable joints.
the skull, is where the brain
and the majority of the If you simply fracture the bone, you may just need to keep it 2. Vertebrae
sensory organs are located. straight and keep pressure off it until it heals. However, if Vertebraefit togetherto
you break it into more than one piece, you may need metal support the body and allow
2. Metacarpals pins inserted into the bone to realign it or plates to cover the bending mCM!flleflts. They
The loog bones in the break in order for it to heal properly. The bone heals by are joined by cartilage
hands are called
producing new cells and tiny blood vessels where the and are classified as
metacarpal~ and are semi·mobile joints.
the equivalent of
fracture or break has occurred and these then rejoin up. For
metatarsals in the
most breaks or fractures, a cast external to the body will be
foot. Phalanges put on around the bone to take pressure off the bone to
located close to the ensure that no more damage is done and the break can heal.
metacarpals make
up the fingers.

"The skull is actually

seven separate plates
when we ore born,
which fuse together"

Skull
When we are born, many of our
..___ _ _ _ 3. Vertebrae bones are still somewhat soft and
There are three main kinds of are notyet fused- this process
vertebrae (excluding the sacrum and
ooocyx) - cervical, thoracic and
occurs rater during our childhood
lumbar. These vary in strength and The primary reasons for the cranium in particular not to be
structure as they carry different fully fused at birth is to allow the skull to Oex as the baby is
pressure wittin the spine. born and also to aUow the extreme rate of growth that
occurs in the first few years of childhood following birth.
The skull is actually in seven separate plates when we are
G. Pelvis 4. Hinged joints 5. Gliding joints 6. Saddle joints
This is the transitional joint between
born and over the first two years these pieces fuse together
slowly and ossify. The plates start suturing together early Both elbows and knees Some movement can The only place we see
the trunk of the body and the legs. It
are hinged joints. These be aDowed when flat this joint in humans is
is one of the key areas in which we on, but the anterior fontanel - commonly known as the soft
joints only allow timited bones 'glide1 across the thumb. Movem ent
can see the skeletal differences spot- will take around 18 months to fully heal. Some other movement in one each other. The w rist is limited in rotation,
between the sexes. bones, such as the five bones located in the sacrum, don't direction. The bones fit bones - the carpals - but the thumb can
fully fuse until late teens or early twenties, but the cranium together and are moved operate like this, m ove back, forwand
7.Femur becomes fully fused by around age two. by m uscles. m oved by ligam ents. and to the sides.
This is the largest and longest single
bone in the body. It connects to the
pelvis with a ball and socket joint.

- - - - - - 8. Fibula/Tibia Baby Six year old Adult

These two bones form the lower
leg bone and connect to the knee
skull skull skull
joint and the foot.

9. Metatarsals
These are the five long bones in
•
the foot that aid balance and
m ovem ent. Phalanges located
close to the metatarsals are the
bones which are present in toes. •

041
 uscles ex ined

Muscles are essential for us to

operate on a daily basis, but how
are they structured and how do
they keep us moving
Amuscle is a group of tissue fibres that
contract and release to control
movements within the body. We have
threedilferent types of muscles In our
bodies-smooth muscle, cardlacmuscleand
skeletal muscle. Skeletal muscle, a Iso known as
striated muscle, is what we would commonly
perceive as muscle, this being external muscles that
are attached to the skeleton, such as bleeps and
deltoids. These muscles are connected to the
skeleton with tendons. Cardiac muscle concerns the
bean. which is crucial as it pumps blood around the
body, supplying oxygen and ultimately energy to
muscles, which allows them to ope.rate. Smooth 6. Abdominal muscles
muscle, which Is normally sheet muscle, Is 'Abs' are often bui~ up by body
primarily involved in muscle contractions such as bt.llders and support the body core.
bladder control and oesophagus movements. These They are also referred to as core
are often referred to as involuntary as we have little muscles and are important in
sports such as rowing and yoga.
or no control over these muscles' actions.
Muscles control most functions within our
bodies; release of waste products, breathing. 7. Quadriceps
seeing. eating and movement to name but a few. The large fleshy muscle
Actual muscle structure Is quite complex, and each group O<>V<!t"ing the front
muscle is made up of numerous fibres which work and sides of the thig h.
together to give the muscle strength. Muscles
increase in effectiveness and strength through
8. Gluteus maximus
exerciseandgrowth and the main way this occurs The biggest muscle in the body,
Is through small damage caused by each repetition this is prinarily used to move
of a muscle movement, which the body then repairs the thighs back and forth.
and improves.
More than 64o muscles are actually present 9. Hamstrings ------~~¥.­
acrossyourenttre body to enable your limbs to Refers to one of the three
work, control bodily functionsand shape the body posterior th9l n-.JSdes. or to the
as a whole. tendons that mal<e up the boo ders
d the space beiW1d the knee.

"More than 300 individual

muscles ore present
across your body to
enable your limbs to work"
042
 1. Gluteus 2. Stapedius 3. Masseter
maximus The smallest llk.lscle In the muscle
The ~uteus maxii'OUS. the body is the stapedius. This is very much dependant
buttock, is the largest which is situated in the on how you define strength.
musde. lt Is a superf;cial middle ear and helps mO\IE! The masseter (jaw) muscle
muscle that helps control the tiny llooeos which aide can exert the highest dir'ect
thigh movement. OUr' heaflng. force on an object.

ltU•JU•11J!3N•IW Skeletal muscles account for around 40 per cent of your total body moss

- - 1. Deltoids
These muscles stretch across
the shoulders a1d aid lifting.
What affects our How the
- - - 2. Trapezius
musde
large, superficial muscle at the
back of the neck and the upper
How strong we are is a combination
part of the thorax, or chest. of nature and nurture Bicepsand triceps are a pair of muscles that work together
to move the arm up and down. As the bicep contracts, the
- - - 3. Pectoralis major Muscle strength refers to the amount of force that a muscle triceps will relax and stretch out and consequently the arm
Commonly known as the 'pees', can produce, while operating at maximum capadty, in one will move upwards. When the arm needs to move down,
this group of muscles stretch contraction. Size and structure of the muscle is important the opposite will occur- with the triceps contracting and
across the chest. for muscle strength, with strength being measured In the bicep relaxing and being forcibly stretched out by the
several ways. Consequently, it is hard to definitively state triceps. The bicep is so named a flexor as it bends a joint,
4. Biceps/triceps which muscle is actually strongest. and triceps would be the extensor as itstraightens the joint
These ann muscles work We have two types of muscle fibre- one that supports
together to lift the ann up and down.
out. Neither of these muscles can push themselves straight,
long, constant usage exerting low levels of pressure, and they depend on the other to oppose their movements and
Each one contracts, causing movement
one that supports brief, high levels of force. The latter is stretch them out Many muscles thereforework in pairs,
in the opposite direction to the other.
used during anaerobic activity and these fibres respond so-called antagonisticmuscles.
5. Latissmus dorsi better to muscle bullding.
Also referred to as the 'lats', these Genetics can affect muscle strength, as can usage, diet L Tricep relaxes - - - - - -..,
musdes are again buit up during and exercise regimes. Contractions of muscles cause
>Neight training and are used to injuries in the muscle fibres and it is the healing of these 2. Bicep contracts
pull down objects from abow. that actually create muscle strength as the injuries are
repaired and overall strengthen the muscle.

"Tendons ottoch muscles

such os biceps to bones,
allowing muscles to move 3. Arm aJrls ..

elements of our body"

L Bicep relaxes

What are muscles made up of?

Muscles are made up of numerous cylindrical Blood vessels and nerves also run through
3. Arm extends ~

fibres, which work together to contract and the connective tissue to give energy to the 2. Tricep contracts
control parts of the body. Muscle fibres are muscle and allow feedback to be sentto the
bound together by the perimysium into small brain. Tendons attach muscles such as biceps
bundles, which are then grouped together by and triceps to bones, allowing muscles to
the epimysium to form the actual muscle. move elements of our body as we wish. What is a pulled muscle,
Epimysium
The external layer that covers the
Blood vessel
This provides oxygen a1d allows
Perimysium
This layer groups
and how does it ha111Je11?
muscle overall and keeps the bundles the musde to access energy for together muscle fibres They hurt like crazy so here's why
of muscle fibres together. musde operation. within the muscle.
it's important to warm up
Apulled muscle is basically a tear in muscle fibres. Sudden
movements commonly cause pulled muscles, and often,
when an individual bas not warmed up appropriately
before exercise oris unfit, a tear can occur as the muscle is
not prepared for usage. The most common muscle to be
pulled is the hamstring, Go... run...
which stretches from gettothe
the buttock to the knee. dlopperl
~------~--~--~-------- A~~~ Apulled muscle may
Myofibrils are constructed
of filaments, which are
resultinswellingand
made up of the proteins pain can last for several
actin and myosin. days before the fibres
repair themselves. To
prevent pulling
---~;:=~- ......------.!..:::-:;:..:....;....!2:~;;::..----- Endomysium muscles, warming up
' _,... This layer SUI'I'<Ulds
- - - Tendon ' - - - - - - - Myofibril each singular muscle
is recommended
These attach muscle to bones, w hich in located within the single muscle fibres, fibre and keeps the before any kind of
turn enables the muscles to move parts nnyofibril.s are bll'ldles of actonnyosin nnyofilril filaments physical exertion.
of the body around (off image). filaments. They are crucial for contraction. grouped together.

043
 kin colour 1 Skin grafts
Melanin and skin colour
Skin co Keratinocytes
These protecti\le cells are procLad
in the lowerlaye<s of the epidem is.
Suface
Basal skin eels rt\inJfacbnd in the
lowerlaye<s d theePderm6!70W
Keratinocytes
The keramocytes of
~- skinned
They take up the meliw:losomes tlvough the skin to the surface. where people take up fewer
procLad by the melanocytes. they are ewntuaty sloo.9>ed lmlrf. melanosomes.

What is melanin and how does DARK ~ UGHT

it affect the tone of our skin? • • •
The light-absorbing pigment melanin Is a • .::;t.=::~S
chemical substance that gives your skin Its
natural colouring. Skin can vary from very dark • • •
. ~
brown toalmostcompletelywhlte due to a
combination ofyourgenesand Inherited tra its and the
amount of sunlight to which you're exposed.
~. •
Skin colour differs from person to person depending on
the concentration of melanin present In their skin and Its
distribution throughout the skin's layers. Basically, those
with less melanin have Ughtersldn, while those with more
of the pigment have darker skin. Melanin Is produced by
specialised skin cells caned melanocytes In the lower
layers of the epidermis and is contained Inside a
meianosome by a very thin membrane.
Exposure tosunllght stlmulates the production of
melanin granules. The meianosomes containing the
melanin then move out towards the skin's protective
keratlnocyte cells along branch cells called dendrites.
Melanin is then stored In the nuclei of the keratlnocytes
• I
Dendrite Melanocyte
where it acts as a natural protector against theeffeetsofthe Melanin is made in the melanocytes. Those wilh ligiUr skin have fewer
Sun'sultravioiet rays. Keratlnocytes make up the bulk PeqJie wilh darlo!r skin, or those melao •• to ke<atinocytes. dendrites in theirlowerlaye<s and
- around 95 percent -of the outer layers of thesklnand who ille in regia IS wi!hgealer their melanocytes are
form the barrier between the body and the outside world. stright exposu-e. have more Melanosomes also less actNe
They take up melanin which canabsorbcancer-<auslng UV active melanocytes. These pad<els d melanin release The meliw:losomes in fl!l>ter skin
radiation so it doesn't get Into the body's Internal tissues. melanin !JGr1Uies ilto the ke<atinocytes. release far fewer melanin granoAes.

Howsking work Skin graft surgery

When our body's largest organ is damaged,

sometimes it needs a helping hand to heal
Skin grafting is a medical procedure where a
portion of skin Is removed and stitched onto
another part of the body. There are many A sterile gali2E
is applied while the ' - - Stitching
cosmetic and medica l reasons why this Smal skin grafts
skin attaches and
might be necessary: serious burns, surgery, tattoo are stitched while
anew blood
removal and some medical conditions (skin cancer or supply estabishes. bigger areas
diabetes, for example) might all necessitate skin grafting. require stapling.
Autograftsaresldn grafts taken from the patient's own
body, usually the buttocks, neck or back of the arm.
Depending on the size of the area that It's removed from,
it's then stitched or stapled closedagalnand the new
sldnapplied to the Injured area.Allograftsand
xenografts, meanwhile- taken from other humans and
Donor skin --~
animals, respectively -are temporary grafts.
The dooorskin is
But perhaps most Interesting Is thearttfldal'sldn' I1!ITll>lle(j and then
called Integra, made of anima Icollagen that gives the appied to the
damaged part an organic scaffolding for new skin to ioitred area.
grow into. This Is usually used In cases of extreme burns
where there isn't enough healthy skin for an autografL

044
 •
•
•• •• •••
• • •
• • Skin varies drastically • •
•• As we~ •• We have billions
STOP Bacteria thrive
on human skin
1
•• You shed skin
• everyday!
:• 2
••
•
••
in thickness
3
• skin th"1ns '
••
4 ••
• of sweat glands
s
FACTS
SKIN
Every ~are inch of an normal
human's skin has an average ol
32 milion bacteria on it... no
matter hoiN many baths or
:
•
••
•
Every 24 hours. you will lose
your uppennost layer of dead
skin oells, helping to keep your
skin fresh and dean and able ••
•
•••
•
Skin isarol.nd lmmthick on
your eyelids, but on your feet
ttws thickness increases to
3rrm. giving )01.1 much more
•
•
••
••
•
Skin thins overtime and begins
to loosen, which is where
wrinkles COI'lle from. and why
people opt f<>< plastk;S<.<g<.'ry
•••

•
•
••
Each square inch of
healthy skin contains close
to 650 sweat glands, which
are essential for keeping
showers you have a day! • lo 1><-eathe. • protection where needed. • in later life. • )'OUCool.

ltU•JU•11J!3N•IW? All mammals hove hair on their skjn, including marine mammals which appear hairless

Find out more about the largest organ in your body...

Our skin is the largest organ in our bodies with an 1. Epidennis 3. Nerve ending .---- 5. Subcutaneous
average individual skin's surface area measuring This is the top, protective layer. It Situated within the dermis, nerve tissue
around two square metres and accounting for up is waterproof and protects the endings allow us to sense temperature, The layer of fat found in the
pain and pressure. This gives us hypodennis that is present to
to 16 per cent of total body weight. It is made up of body against UV light, disease and
information on our environment and p"""'nt heat loss and protect
three distinct layers. These are the epidermis, the dermis and dehydration among other things.
bone and m.tscle from
stops us hurmg ourselws.
the hypodermis and they all have differing functions. damage. It is also a reserve
Humans are rare in that we can see these layers distinctly. energy source.
The epidermis is the top, waterproofing layer. Alongside
helping to regulate temperature of the body, the epidermis
also protects against infection as it stops pathogens entering 2. Dennis
The layer that nourishes and
the body. Although generally referred to as one layer, it is helps maintain the epidennis,
actually made up of five. The top layers are actually dead the dermis houses hair
keratin-filled cells which prevent water Joss and provide roots. nerve endings
protection against the environment, but the lower levels, and sweat glands.
where new skin cells are produced, are nourished by the
dermis. In other species, such as amphibians, the epidermis
consists of only live skin cells. In these cases, the skin is
generally permeable and actually may be a major
respiratory organ.
The dermis has the
connective tissue and nerve
endings, contains hair
follicles, sweat glands,
Jymphatlcand blood
vessels. The top layer of the
dermis is ridged and
interconnects securely
with the epidermis.
Although the
hypodermis is not actually
considered part of the
skin, its purpose is to
connect the upper layers
of skin to the body's
underlying bone and
muscle. Blood vessels and
nerves pass through this
layer to the dermis. This
layer is also crucial for
temperature
regulation, as it
contains 50 per cent
of a healthy adult's
body fat in
subcutaneous regulation, this is
tissue. These kinds of where sweat is
secreted to cool the
layers are not often body down when it is
seen in other species,
humans being one of few
~ becomingtoohot.

that you can see the distinct

layers within the skin. Not only
does the skin offer protection for How your
muscle, bone and internal organs, but it is
our protective barrier against the
environment. Temperature regulation,
skin works
The skin is made of many more
insulation, excretion of sweat and sensation are justa
few more functions of skin. elements than most people imagine
•
045
How does this condition cause intense
inflammation of joints and the eventual
destruction of cartilage tissue?
Rheumatoid arthritis Is a response, but It Is thought that it
chronic and progressive Involves a body's genetic susceptibility
dlseasethateffects many to certain vtruses. Regardless however,
people around the world. once activated by such a cause, a series
Through inflammation throughout of Immune system reactions proceed to
the connective tissues of the body, It cause unwanted/abnormal levels of
causes irreversible damage to Inflammation and tissue/bone
individuals' joints. The disease develops destruction within the body.
when a person's body generates an Inflammation is caused by a heavily
autoimmune response- a mlsta i<en abnormal Interaction between B-cells
immune system reactlonagalnstlhe and T-cells (see 'Cellular-level
body's own tissues- that attacks Its joint development' boxout below), a complex
components rather than the hostile process that causes a variety of proteins, Extreme swelling and
invading organisms. antibodies and other cells to be released Inflammation caused by
As of now, scientists are unsure of which break down joint cartilage rheumatoid arthritis
what instigates the autoimmune among other damaging activities.

of
The cellular mechanisms, proteins and antibodies
involved in the development of rheumatoid arthritis
Ek:els Osteoc:lasts T-cells
8-oells are lymphocytes (white blood eels) that make Osteoclasis are terminaly <ifferentiated cells of the Similar to 8-<:ells, T-<:ells differ in the fact that they
ao1ttxxles to combat antigens. These cells lntemaise macrophage lineage that re-abso<b bone matrlx. ln hM! $I)OOial receptors on their Slriace. They assist
antigens befooe preserting them toT-eels. rfleuTiatoid arthritis, they aid joint destruction. the matl.l'ation of 8-oells into plasma cells.

;.· ~
••
••

-· .. •
••
••

•., •• • ••
~·
•
•

~ ..•
~ '!f
•••• ••

· · · ~··· ·

Plasma eels L - - - - - - - - - Macrophages '--------- Synovial membrane

Plasma cells deoelop when 8-oells are activated t.nder The role cl the macrophage is to engulf and digest The s}'nOIIial ,.,.., b .... is the soft tissue that ines the
stiroolation by T-<::el5. They are a larger and""'"' ......... debis and ~d-- OS, stilrulate 8-oells and non-<:artiaginc surfaces within joints. Wdh rheunatoid
SPOOialised~oell release enzymes and "'oo,;, 15.

046
I•U•JW•1!113N•l!i'i> Bone morrow constitutes approximately 4"/o of the total body moss of humans

•
ns1 eour nes
Learn how bone marrow can transform cells into whatever the body needs
The skeleton is not only used as the cells in the blood, from oxygen-carrying red In an adult human, most of the long bones are
body's main structural support, itis blood cells to bacteria-munching macrophages. filled with yellow bone marrow - mostly made
also home to the largest collective The majority of these stem cells are contaIned up offat cells - howeverthis can be converted to
reserve of adu lt stem cells within us. in the red marrow, which gains its colour from a red marrow for blood cell production should an
Bone marrow is a soft tissue present inside all rich network of blood vessels. The stem cells are emergency arise.
the long bones of the limbs, a nd inside Hat supported by a range of other cells collectively Bone marrow also contains a second,
bones such as the pelvis, s kull a nd ribs and it is known as stroma. The stromal cells provide the less-studied population of stem cells known as
jam-packed with haematopoietic stem cells. right microenvironment for the development of mesenchyma I stem cells (MSCs). These are able
These cells are only partly committed to their stem cells into the blood's components, making to produce the basic elements that make up the
development pathway, so depending on the a range of growth factors to encourage cells to con nective tissues of the body, including fat
signals they receive, can become any of the differentiate down the correct path. cells. bone cells and fibroblasts.

Bone marrow in context The origins of blood

What is going on i nside one of the long bones in our legs?
See how bone marrow is a f actory capable of producing
I ~ l:'ood...

Compact bone 1. Haematopoietic

Compressed layers of stem cell
mineralised bone on This stem cell In red bone
theouCSlde provide marrow!sable to develop
structural support. lntoseoleral dlflerenttypes
of cell depending on the
signals it receives.
Osteon ___, MeduUary cavity
The compact bone Our long bonesale 2. Common
that supports the legis mostly bollow,and the
made up of seve-a! bone marrow Is stored m yeloid progenitor
coocentrtcsystems, Insidea cenaal c.av11y. TheHSCgraduallyrommits
constructed from to becominga particular
layers of bone. type of cell Eachstep In
development narrows down
the optlons.

-~ Bone marrow
In an adult, most of the 3. Common
Blood supply
Thestemcellsare medullary cavity Is I!Ued
with yellow marrow, lymphoid progenitor
generally unable to leave Once an HSC becomes a
the bone marrow; only while the red marrow Is
restricted to the ends of \!~=-- lymphoid progenitor, ills
fully developed cells can committed to becoming a
enter the bloodstream. the bones.
lymphocyte (eg 8-cellswhlch
make antibodies~

4 . Macrophage 4 . Dendritic cell

Which cell the common These playa vitalrole In
myeloid progenitor the Immune system.
becomes depends on capturing antigEns and
what the body needs. flaggingother Immune
cells to take action.
4 . Erythrocyte
Red blood cells are
Endosteum the most common
The Inner surface of the 4. Platelet
bonelsllnedwlth type of blood cell and
cacryoxygenaround These are small cell fragmentS InvolvedIn blood
bone-generating cells clotting. and are created by bagmentatlon of huge
called osteoblasiS, the body.
cells called megakaJYOCY!eS.
which also belp to
~
support the stem cells. !:

L---------------------------------------------------.J ~
047
 Lfl
n
-·
ro
Spine curvature ::J
n
Asyoulook at the human sph1e,you can
seesomedlstlnctcurves. The primary
ro
reasons for these are to help distribute
weight throughout the spine and support
aspects of the body. The cur~~e most
familiar to us Is the lumbarcurve,
-::r
a
r-t-

between the ribs and pelvis. This ro

develops when we start to wall< at about
12-18 months and helps with weight cr
distribution during locomotion. Prior to a
thlswe develop the cervical curve, which n
allows us to supportthe weight of our A'
").._ __,._ head at around three-four months, and cr
two smaller less-obvious curves In the a
spine(the thoradc and pelvic curves) are ::J
developed during gestation. ro

Soipal cords
ahdnerves
The humanspinalcord Isan Immensely
complex structure made up of nerve cells
and a large amount of supporting.
protectl~~e ttssue.ltsplltslnto)l different
sectionsandstretcheS4)·45cm,down
from thebraln to between the first and
second lumbarvertebrae. Although more
commonly referred to In respect of the
brain. there Is both white and grey matter
present in the centre of the spinal cord.
White matter contalns axons tracts
surrounded by fats. and blood ~~esselsto
protect them. Thegreymattercontalns
more of the neural cell bodies, such as
dendrites, more axons and glial cells.
• Spinal cord Injuries are normally
caused bytrauma.lfthetraumacauses
Intervertebral discs and vertebrae to
breal<, they can plercethesplnal cord,
which can result In lossoffeellng. Cord
severance may result In paralysis.
•

\
 •

b'ric
... '
•
•
• • - Vi _ - . .- - - . •
- ~

-
~
-

-·- --·
0
10
rtl
r::_-,
:J
~
rtl

..,~
• • ll'll'iile .
How is the skull ~
rtl
CT
~~: ~ u~ !""
attached to the a
- ~a:r
~..
c~
. 111
g. ~

spine? 0.
or ~~;r.~~
og. .. !l!~ Ill

The sl<uU is connected to the spl ne by the £ ~ ~ ~f ;! ~

• • f w1thstand the atlanto-occipital joint, which Is created 0 - ~- H
;;I "'
• n U1

by Ct (atlas) and the occipital bone c:0

situated at the base of the cranium
(slruiQ. ThJsuniquevertebra has no -
IE"
'body' and actually lool<s more IU<e a 11 ng
than any other vertebra. It sits at the top
g ...,
of the cervical vertebrae and connects rn- ••
with the occipital bone via an eUlpsoldal c:
1J
joint, allowing movement such as rv
noddJngor rotation of the head.An l1l
~
eiUpsoldal Jol ntis where an ovoid
0
-,
connection (In this case tile ocdpital
• ...r.......:_ .,..,. 'fi,;o::-;r:....~ ·~
bone) is placed Into an elliptical cavity (C1 ~
:r HBff !'l
vertebrae~ The restofthecervical
rtl
V1
pH"
-i ~~i
.. ~
~~ l~5' l
:-J
vertebraealsoworl< to support the weight 1J
~i~~~ -·
oft he head. rtl !"~"'~ .. .,.
~~:t .. ~ i'
-
Vl.

~
10
. i~~~: ; ~

~
:r

Neck
The bones
Skull olthe neck
(cervlca
surround the vertebroo)
spinal cord, nre p.1rt ol
the splrlC.
.. g:i? W
i
which connects ~i
the brain to 11" ~ ~ "'~ .
!l!. ii g "'· ,.. C)
t ~~ iH ~
nervous
system.

~h~H ID
~aHJ
 eart attacks explained
----------------------------------------------------
What causes heart attad<s and
how do they kill?
A heart attack, also known as a generation of coronary artery disease (CAD).
myocardlallnfarctJon, occurs This is where arteries are constricted due to
when a blockage stops blood plaque build-ups and this layer then ~- . -----------m~~

- *
oxygenating the heart muscle. If ruptures. Blood platelets make their way to
this is not corrected quickly, the muscle the site of rupture and start to form blood
tissue that is lacking oxygen can become clots. IIthese clots become too large, the
damaged, or indeed die. The scale of Impact narrowedarterywill block and a heart

·---- •
on the individual's health aftertheattack Is attack occurs. Heart attacks can also be
dependant on how long the blockage occurs caused by coronary artery spasms,
for, what artery It affected and what butthese are rare.
treatment was received. Following the Although some people 1
initial attack, heart failure or a rrhythmlas will be genetically
can occur, both of which may prove fatal to predisposed to heart
the victim. However, given the right attacks, Individuals
treatment many sullerers go on to rna ke can reduce risk by
good recoveries and can eventually return keeping their weight
to their normal activities. down, watching what
The most common reason for heart they eat, not smoking and
attacks worldwide in humans Is the exercising regularly.

L Coronary arteries 4. Blockage occurs

These are the arteries that ...,py the heart Either tlvough eYCA!Ss dotti og or 1\.nher deposit buikkJp, a
wilh blood. They are crucial to lco<!prog the blod<age can oca.r. This means blood flow cannot get tiYough
heart ~eftect!wly. Ill aland the lack of oxygen resUts in heart tissue dying.

Coronary artery
(supplies blood
and oxygen to
heart muscle)

3. Plaque rupture
Plaque becomes hardened as
it builds up, and it can rupture.
Coronary
artery If it ruptures, platelets gather
to clot around the rupture.
which can cause a blockage
tooo:ur.

Heart muscle - -

5. Dead tissue--------
Due to alack of oxygen.~
'----- 2. Plaque build-up
Plaque, made up of inllanmatorycels,
sections of heart rrusde can die off. L--- Dead heart muscle Jll'oteins, fatty deposits and calcit.m.
This can redJce effectiveness of the narrows the artery and means that ooly
muscle as a whole following reecM!fY. a redJced blood flow can get throug:l.

050
 ••• •
•
•
•
•
•
• • •

STOP Risk scores

1 Using complex mathematical
How much does it cost? : How much blood?
2 Theop is free on the NHS but in • :3
On average, the heart beats 70
Beating heart bypass

4 A bvpasscan be performed •
: s
: New techniques
New techniques indude using

FACTS
models, each individual patient is the private sector it would oost • times per minute (about without stopping the heart. • minj.inc:isions into the chest
given a risk of dying from the £16,000-£20.000 ! 100,000 times per day} which using a special retractor. tn a few ! and also the use of robots.
operation, alowing them to make ($23,300·$29.000). Thepric<! ! pumps five litres of blood per places. surgery has been ! Smalcamerasarealso used to
a decision about how risky the varies with the risks and if it's the ! minute. F"tve per cent flows : performed this 'NaY on patients : harvest the new vessels for the
BYPASSES operation is. first surgery or a re-do. ! through the coronary arteries.. : who are awake. ! bypass grafts.

ltU•JU•11J!3N•IW The heart has four separate chambers, four valves to control blood flaw and twa main coronary arteries

3. Bypassing
the heart - - - - --.
Blood is removed by pumping
Heart bypass
it out of the body, oxygen is What happens in surgery?
added to it in a bypass machine
and the blood pumped back in.
This a llows oxygenated blood
to continually flow while the
heart is stopped.
, - - - - 1. The problem
Fatty plaques narrow and
4.Stopping eventually block the
the heart -
The aorta, the main
- - --+-- coronary arteries,
preventing oxygen-rich
vessel out of the blood flowing to the
heart, is damped. heart m uscle.
The heart is then
cooled and stopped
using a potassit.m·
rich solution.

6. Restarting
the heart
Once the new vessels
have been secured, the
- : J"O - - - - -2. Getting to
~
aorta is undamped
which washes the the heart
potassium-rich solution
from the heart. The - - -
The chest is opened
through a cut down the grafts
patient is warmed and m iddle of the breastbone The body has certain
(sternum). A special bone vessels which it can do
the heart restarts.
saw is used to cut through
without, and these act as
the sternum, which doesn't
damage the heart below.
conduits for bypass
5. Attaching the - - surgery. Commonly
new vessels used,thelongsaphenous
The new 1/<!Ssels are tested and vein runs from the ankle
then sewn into place. The opening 7.0osing to the groin. Ashallow
is sewn to one of the large arteries +-- - - the chest incision allows the vein to
carrying oxygen-rich blood. The After making sure there is
end of the bypass graft is sewn no bleeding, thin metal
be dissected away from
beyond the fatty plaque, aDowing wires are used to hold the Its surrounding tissue.
blood to freely flow to the two halves of the sternum Other vessels often used
affected heart muscles. back together. include small arteries
from behind the rib cage
{Internal mammary
artery) or the arms
(radial artery).

StoP.Ping
theliean
Cardiopulmonary bypass
(where a machine takes
over the heart's pumping
action and the gas
When too little blood is getting to the muscles of the heart, a exchange function of the
surgeon can bypass the blockages using the bodys own vessels lungs) is established to
provide oxygenated
Although the heart pumps of oxygen- angina. Ifa vessel becomes The surgeon uses healthy vessels from blood to the rest of the
oxygenated blood around the completely blocked, no blood gets other parts of the patient's body to body. Next, the heart is
body, the heart's muscular through, causing a heart attack where bypass the blockage, allowing a new stopped. This is achieved
walls need their own blood the heart muscle dies. route for blood to flow. This delivers using a potassium-rich
supply. Oxygen-rich blood is delivered to The first way to treat this type of higher volumes of the oxygen-rich blood solution, pumped down
these tissues via smal Ivessels on its coronary artery disease is with to the heart muscles beyond the the coronary arteries.
surface- the coronary arteries. These medicines. Secondly, angioplasty can be blockage, preventing the pain. This stops the heart
arteries can get narrowed or blocked up used, where narrowings within the Most bypasses are performed by contracting. The surgeon
with cholesterol causing fatty plaques arteries are stretched using a balloon, stopping the heart and using a heart- can now carefully attach
which slow blood flow. At times of with or without placing a stent to keep lung bypass machine to deliver the fresh vessels to
exercise, not enough blood gets to the the vessel open. Finally, a heart bypass oxygenated blood to the body. The new bypass the blockages.
heart muscles, leading to pain due to lack operation is an option for some patients. vessels are then sewn into place.

051
 •
sctence blood transfusions
------------------------------~------ r-~~
Noone can get
a transfusiOn
unless blood
donors keep
What's in
ondona!lng

Red blood cells

- blood eels are the most
abundant cells in blood and
gM! it a red colour. They carTY
oxygen from the lungs iii"<J<W1d
the body, boo.nl to a prcn;,
caled haentoglobi!L

Plasma
Plasma is a straw-<:dowed
walefy fluid that carries ..
of the cells and proteins in
blood, incbling the vital
clotting factors.

Platelets
Platelets are tiny frayooOBots of
blood that are aucial in
st01>1>ing bleeding, along with
clotting factors, by fomoio og a
plat-plug.

White blood cells

These are yow irilecticwr-
f"o9otioog eels; theyc:irculab!
Whether it's a patient ~ Safety first
in the blood so they can

haemorrhaging to Two nurses rn.ost double check the Receiving qooiddy nWJitiply and be
b30~ to an area where
there's an ioftdiooo flaring.

death or a 'top up' for

de!ails on the bag of blood with the
patient's ide llify label befol"
administe i ~ it.
a blood
Lymphocytes
life-long diseases, lyrT111oocytes are a type of
Blood screening
blood transfusions All blood transfusions are rv:tN
The pallent Is atta.ched to a
drip and the donor blood Is
- blood cell that dio ects
the body's immune system.

are vital procedures saeened fu< HIV, hepatitis iWld otller

infections carried .. blood. transfused through this.
They have a memory fu<
invading bacteria and viruses.
"fYplcallyanarmveln Is
Ablood transfusion takes
• •• - place when a pallent Is given
components of blood from a
normally used.

' ~

' donor when their own blood

levels are too low. Having enough blood
is essenUal because It carries oxygen
around the body and returns carbon
dioxide to the lungs to be ex haled as a
The ABO
waste product. blood groups
We all belong to one of fOUl' blood
When a doctor deddes a pallent needs types (below). Different antigens
blood, they are 'cross-matched' with ~- Blood pcesent on the surface of red blood
donor blood. Afew mlllllitresofthelr cells identify to which group you
The blood is in a sterie, clear
belong_ A patient mtl'St receive
blood is collected Into a sma II bottle bag containing the details of blood with the correct antiqens or
which must be hand-labelled to prevent the blood group iWld type, iWld else their · e system wil
confusion between pallents.l n the lab the patient's detais it is recognise that the red blood ceUs

the blood Is matched with donor blood of intended fu<. are foreign cells and wil attack.

the same group (either A, Bor 0). The • A antigens on red blood
unit of donor blood Is then transfused cells and anti-8 antibodies in
plasma
via a drip into the patient's veln over two
• B antig<>m on red blood
to three hours. cells and anti-A anhbodies in
During this time the nurse keeps plasma
close observation of the patient to look • A and B antigens on red
for transfusion reactions. These can be ~~=-:--
-::---:--::~e. ~~:-.;;==.,::~:J blood eels and no antibcxlies
in plasma
mild (such as a fever, chills or a rash), which is placed directly • No antigens on red blood
which are solved byslowlngdown the into the patient's win so cells and anti-A and anti-B
rate of flow, to severe, life-threatening the transfused b lood joins antibodies in plasma
allergic reactions. the cirrulatilg blood.

052
 •• •
•
•
•• •••
•• •
•• Orthopaedics •• Gastrointestinal bleeding •• Childbirth
STOP 1
Anaemia
One ~arterof blood
• Haematology
•
:2 Some patients have blood ••
•
•3In orthopaedic surgery .. such
•
•
•• 4 Blood loss (rom the •
•
••sThe fifth most corrvnon

FACTS transfusions are ~nto : disorders where their own red as spinal fusion and hip gasb'ointestinal tract. such cause of blood transfusion
•• •• ••• •• •
patients with anaemia. whose bloodoeAs are deficient. such artiToplasty - blood is lost as stomach ulcers and is t\Jring or following
blood levels have been '*-;ng • as in sickle ceH disease or red
•• during the operation. This is • oolorectal cancer. accounts • trai..IITB'tic childbirth. Normally
slowty over tine due to
•• cells destroyed at a high rate •• common with large joint •• for 11 per oent of all human •• blood toss during chadbirth is
BlOOD diseases like cancer. -• called haemolysis. •
• replacement surgery.
•
• bbod transfusions.
•
• less than 600ml.

ltU•JU•11J!3N•I'AW The first ever successful blood transfusion was performed on o dog in 1665 by Richard Lower

How the body reacts to blood vessel

The loss of blood supply to the brain damage to aia the healing process
can cause long-term damage or death Through the action of the thrombin system, coagulation of
Strokes are caused when the flow of blood to the brain is the blood occurs instantly at the location where there is a cut
interrupted. There are two main reasons why this might or other injury to the skin. The blood clot, which consists of a
occur, and ischaemicstrokes are the most common. They combination of cellular platelets and sticky strings of fibrin,
occur because of a blood clot that forms in an artery forms a plug in the damaged blood vessels.
(thrombosis) or a blood clot that forms and travels to a brain artery {arterial The clot stops blood from freely flowing out of the body and at the
embolism) that reduces or blocl<s the blood flow{ischemia). same time allows the blood to continue circulating. As the skin heals,
The second reason is bleeding (haemorrhaging) of a blood vessel in the plasmin enzymes break down the webs of fibrin and the clotis
brain. This can be caused when a thin part ofa vessel{ananeurysm) eventually dissolved into the body.
bursts. Between one and six per cent of the population have an Clots can also form in blood vessels due to inactivity, old age, obesity,
intracranial aneurysm and every year in the United Kingdom 1,400 people smoking, poor diet or during pregnancy. This condition is known as
die of ruptured intracranial aneurysms. thrombosis and can lead to an embolism.
Astroke is defined when it either causes death or has a long-term effect
after24 hours. You can experience signs of a mini stroke that are called
transient ischemic attacks (T!As) that last only a few minutes or hours. The
onset of a ful lstroke is characterised by numbness in the face and limbs.
Vision can be impaired and you can have trouble wall<ing or talking.
The effects ofa stroke depend on which part of the brain was most L Skin layer ------::~~
starved of oxygen from the blood supply. In many cases, stroke victims Composed of a water·
resistant and protective layer
will find it difficulttowalkoreat due to musclewealmessand in extreme called the epidermis; beneath
cases, they might experience paralysis. it is the dermis layer that
consists of blood vessels and
connective tissue.

Areas of impact
Carotid arteries ~-- Vertebral arteries
Carotid blood vessels, served by Vertebral arteries supply blood
the internal and external carotid to the rest of the brain and
arteries, supply blood to the front enter the skuR through the
part of the cerebrum. foramen magnum. 2. Cut -----~
If skin is cut, platelets in
the blood wssels of the
damaged a-ea become
'sticky' and clump
together at the damaged
site to funn a white clot
Other chemical reactions
create sticky web~il<e
strands of fibrin that
adhere to the damaged
blood vessel wal~ to fonn
a red clot.

Strands of fibrin - - - - - - '

Platelets _ _ _ _ _ _ _ __,

3. Healing -------~
The blood clot stops
blood escaping from the
wound, and allows the
normal circulation of the
red blood cells which
transport oxygen around
the body and the white
blood cells that protect it
against infection.
lsdlaemic strokes are caused by blood clots, When part of a thin
which can either funn directly in an artery, or blood vessel bursts
funn and then travel to a brain artery that it haemorrhaging
then blocks, reducing blood flow. can occur.

053
 ow your kidneys work

Inside
As blood enters the kidneys, It Is passed
through a nephron, a llny unit made up of
blood capillaries and a waste-transporting
tube.These work together to filter the blood,
returning clean blood to the heart and lungs
for re-oxygenation and recirculation and
....
How do your kidneys filter
removing waste to the bladder for excretion.
-
waste from the blood to
keep you alive?
Kidneys are bean-shaped organs Renal cortex - - - - - - - - - -
situated hallway down the back This is ooe of two broad intemal sections of the
just under the ribcage, one on kidney, the other being the renal medulla. The
each side of the body, and weigh renal tubules are situated here in the protrusions
that sit between the pyramids and sean the
between u5and 170 grams each, dependent
cortex and medulla together.
on the individual's sex and size. The left
kidney is commonly a llttle larger than the
right and due to the effectiveness of these Renal artery - -
This artery Sl.Wfies the
organs, individuals born with only one kidney with blood that
kidney can survive with llttle or no adve.rse is to be fitered.
health problems.lndeed, the body can
operate normally with a 3o-40 per cent
decline in kidney function. This decline In
function would rarefy even be noticeable
and shows just how effective the kidneys are
at filtering out waste products as well as
maintaining mineral levels and blood
pressure throughout the body. The kidneys
manage to control all of this by working with
other organs and glands across the body
such as the hypothalamus, which helps the
kidneys determine and control water levels Renal vein
in the body. After waste has
Each day the kidneys will filter between been removed. the
150 and 18o lltres of blood, but only pass clean blood is
passed out of the
around two lltres of waste down the ureters kidney via the
to the bladder for excretlon. This was te renal vein.
product is primarily urea- a by-product of
protein being broken down for energy-and
water, and It's more commonly known as
'urine'. The kidneys filter the blood by
passing it through a small filtering unit
called a nephron. Each kidney has around
a million of these, which are made up of a
number of small blood capillaries, called
glomerulus, and a urlne-<:ollectlng tube
called the renal tubule. The glomerulus sl.ft
the nornlal cells and protelns from the blood
and then move the waste products Into the
renal tubule, which transports urine down
into the bladder through the ureters.
Alongside this filtering process, the
kidneys also release three crudal hormones Ureter Renal medulla RenaJ ---l
(known as erythropoietin, renin and The ttbe that This fmnel-likr s1rucbJre i; The kidney's iMer section, where blood i; capsule
calcitriol) which encourage red blood cell trarosports the waste howo.rile travels out of the filtered after passng through rumerous The kidney's filrous outer
products (o.rile) to kidney and forms the top part a-tet ioles. It's spit into sections called edge, wnch provides
production, aid regulation of blood pressure protection for the
the bladder folowing of the tnter, wNch takes py!1111 lids and each tunan kidney wil
and aid bone development and mineral blood 61traoo.. normaly have seven of these. kidney's 0rtema1 fibres.
o.ri1e down to the bladder.
balance respectively.

054
 Two for the price of one
We are thought to have two kidneys because they are so crucial to oursurvival,
the second is purely a 'back up'. Having two organs obviously increases our
chances ofsurvival and reproductive fitness.

ltU•JU•11J!3N•IW Useless body ports include the appendix, the coccyx and wisdom teeth

r---------------------------------------·
I
I Nephrons - the filtration Collecting
duct system 1be glomerulus
I This group of capillaries is the first step of
I units of the kidney Proximal tubule
Although not
technically part of the filtration and a crucial aspect of a nephron.
I Nephrons are the units which filter all blood that passes Unks Bowman's cap5Uie nephron, this collects all As blood enters the kidneys via the renal
I and the loop of Henle, waste product filtered artery, it is passed down through a series of
through the kidneys. There are around a million in each by the nephrons and
I kidney, situated in the renal medulla's pyramid structures. As and w ill selectively arterioles which eventually lead to the
reabsotb m inerals from facilitates its removal
I well as filtering waste, nephrons regulate water and mineral glomerulus. This is unusual, as instead of
the filtrate produced by from the kidneys.
I salt by redrculatingwhat is needed and excreting the rest. draining into a venule (which would lead
Bowman's capsule.
I back to a veln)itdrains back into an
. ... .~ arteriole, which creates much higher
pressure than normally seen in capillaries,
which in turn forces soluble materials
Glomerulus and fluids out of the capillaries. This process
H i~ pressurein the is known as ultrafiltration and is the first
glomerulus, caused by it step in filtration of the blood. These then
c%aining into an ateriole pass through the Bowman's capsule

-.. ,
instead of a venule, (also know as the glomerular capsule) for
foroes fluids and soluble
further filtration.
materials out of the
capillary and into Afferent arteriole Proximal tubule
""":-- +-- - Bowman's cap5Uie. This arteriole supplies the Where reabsorption of
blood to the glomerulus minerals from the
--+- '=-"""+-- Bowman's for filtration. filtrate from Bowman's
capso..M ,;11 oocur.
capsule
Also known as the
glomerular capsule, this
filters the fluid that has
been expelled from the
glomerulus. Resulting
filtrate is passed along
the neptvon and
will......rtually make
up urine. Thismassof
capilaries is the
glomerulus.
- - i' - - - - - - Distal
convoluted
tubule
Partly responsible
for the regulation of
minerals in the Bowman's
bdood, linking to the Efferent arteriole '--- capsule
collecting duct This arteriole is how This is the surrounding
system. Unwanted blood lealles the capso..M that wil filter
minerals are glomerulus followng the filtrate produced by
excreted from ulbafibation. the glomerulus.
the nephron.

Renal artery
This artery supplies the
What is urine and what
kidney w ith blood The
blood travels through
is it made of?
this, into arterioles as you Urine is made up of a range of organic 94o/o water
travel into the kidney, compounds such as proteins and
ootil the blood reaches hormones, inorganic salts and
the glomerulus. numerous metabolites. These
by-products are often rich in nitrogen
and need to be removed from the blood
Renal vein stream through urination. The pH-level
This removes blood that has of urine is typically around neutral
been filtered from the kidney.
(pH7) but varies depending on diet,
hydration levels and physical fitness.
Renal tubule The colour of urine lsalso determined
Loop of Henle Made up of three parts, the proximal by these factors, with dark-yellow urine
The loop of Henle controls the mineral and tubule, the loop of Henle and the distal
indicating dehydration and greenish
water concentration leliels within the kidney convoluted tubule. They remove waste 6% other organic
to aid filtration of fluids as necessary. It also and reabsorb minerals from the filtrate
urine being indicative ofexcessive
asparagus consumption. compounds
controls urine concentration. passed on from BcMrman's capsule.

~~--~--~-------~------~----------·
055
 Kidney transplants

The kidneys are the body's natural filters. You can survive
on just one, but when that fails you may need a transplant
Transplanting organs is a year receive their transplant. The someone else's fortune. for those who register to a suitable recipient A
complex process, although number of patients registered for a are declared brain-dead, the beating ·retrieval' team from a central
it can give a new lease of life kidney transplant Increases each year, heart will keep the kidneys perfused transplant unit (of which there are 20
to recipients. The lddney is and has risen by 50 per cent since 2000. until they are ready to be removed. In based around the UK) will go to
the most frequently transplanted Kidney transplants come from two some patients, the ventilator wUl be whichever hospital the donor is ln.
organ, both in the UK and around the main sources: the living and the switched off and It's a race agal nst lime They will remove the organs, while the
world. However, there Is a discrepancy recently deceased. If a healthy, to harvest organs. Either way, consent recipient is being prepared in the base
between the number of patients compatible family member is willing to from the family Is needed, even at such hospital. During the tricky operation,
waiting for a transplant and the donate a lddney, they can survive with an emotional and pressurlsed Ume. the new kidney is 'plumbed' Into the
number of available organs; only just one remaining lddney.ln other When a suitable organ becomes pelvis, leaving the old, non-functioning
around one third of those waiting per cases, someone else's tragedy is avallable, it is matched via a nat.lonal ones In-situ.

( to per f01111 a kidney transplant

Transplanting a lddney Is 1. Thedonor ,....- 2. Out with the old? 3. Into the pelvis
a case of careful and The donor kidnoy .. harwstl!d, indu!ing en<llJ!jllength at As long as !here's no <JJOSticn An incision .. made in the
clever plumbing. The first artery. ....... and ..-eter (which carries lAine to the bladde<) at cancer. the original kmeys lower part at the abdomen to
step is to harvest the t o - tl!n5iorHn!e irniJiantation i1ID the re<:ipielll. are left in place. gain a<X>'S5 no the pelvis.
donor kidney, and then
it's a dash to transplant
the new lddney Into the 7. What's that
recipient When the lump?
brain-dead donor is The new kidney can
transferred to the be felt underneath
operating theatre for the sea< in the
organ harvest, they are recipient. These
treated with the same patients are often
care and respect as If they reauited to medical
student exams.
werestlll alive. When
consent has been given
for multiple organ
harvest, a cut is made
from the top of the chest
to the bottom of the B. Catheter
pelvis. The heart and A catheter i!>left
lungs are retrieved first. in-situ fa< a short
followed by the while. so that the
abdominal organs. lrine output of the
new kmeycan be
meastnd exactly.

5. PIU'l'Dng it in
The renal artery and .......
are cmnected to the
~~dng~artery --------~------~
I
and ....... in the redpie ~··
body. Holes (a leliutoories)
are created in the main
arteries, and the kmey's 4. Make space! " - - - - - - - - - - - - - - 6. The f inal link
YeSSels are anasiDmo5ed The ...-geon wil aeate space in the pelvis. and identify the large The treler, which drains lAine from the kidney, ..
(,a SU'gical join between YeSSels which run from the heart to the leg (the iiac arteries and cmnected to the bladder. This alows the kidney to
two IUJes using sutures}. ~. The new kidney's YeSSels llwil be connected to these. function in the same~ as one of the original kmeys.
-
056
 •
• •• ••
•
•
•
•• Which other organs? ••
• Through the keyhole Do something about it
Pioneers
1 Thewryf;r.;tkidneytransplant
totakeplaceintheUK was
•• The 'organ gap'
•
••
•
2
Aro111d 7,000 people i'l the
United Kilgdom last year
•
•
••
•
3 Organs that can be
transplanted incble kidneys,
•
•
••
•
4 When removing a kidney from a
liWlg donor, the most modem
s You can register to
become an organ donor

•••
performed in Edinburgh. 1960. were waiting for organ livers. hearts, lungs. the at http://www.
••• •••
centres use keyhole surgery
Here a surgeon transplanted a transplants. but only around pancreas and intesOOes; tissues ()aparoscoP1f}lodol • this organdonation.nhs.uk/
kidney from a 49")'eaf''id into •• 2,.300 kidney transplants •• include bones. heart vatves,. •• leads to smaler scars.less pain - don't forget to talk to
his twin brother. • actually took place. • skin and ccwneas. • and faster recovery. )'OUr kwed ones about it.
• • •

1•U•Nl!l!J13.,-C•1WP Of the millions of people in the UK suffering from kidney disease, sa.ooo will suffer end-stage renal failure

Dom·
Patient1 needs a new kidney but their
family member isn't compatible.
Patient zalso needs a kidney and has
an lncompatible family member as
well. However, patient2's relation is
compatible with patient 1 and vice
versa. The surgeon arranges a swap-
a 'paired' transplant. Alonger line of
patients and family members
swapping compatible kidneys can be
arranged-a 'daisy-chaln' transplant.
A'goodSamaritan' donor, who isn't
related to any of the redpients, can
start the process. This first redplent's
family member will subsequently
donate to someone else- a 'domino'
transplant effect which can go on for
From patient 1 From patient 2
several cycles. family inember flllolily member

Who is Antibody
If the antigens are too dissimilar, the host's existing
immune system thinks the new ki~ey is a foreign invader
and attacks it with antibodies, leading to rejection

Of the several miUion people in

the UK with kidney disease, only
around 50,000 will develop
end-stage renal failure (ESRF). For
these people, dialysis or kidney
transplantation are the only
options. Kidney damage from
diabetes is the most common
cause of transplantation. Other
causes include damage from high
blood pressure, chronic kidney
scarring (chronic pyelonephritis)
and polycystic kidney disease
(the normal kidney tissue is Antigens
replaced with multiple cysts~ Antigens from the recipient kidney's ABO
many other less common causes blood IJ'OUP and HLA system should be as
exist also. close a match to the donor's as possible.
Patients must be selected
carefully due to the scarcity of
organs. Those with widespread
cancer, severely calcified arteries,
persistent substance abuse and
unstable mental problems mean
that transplants are likely to fail When things go wrong...
and so these patients are Kidneys need to be carefully matched to suitable donors, or rejection of the new organ
unsuitable to receive a precious will set in fast. Rejection occurs when the host body's natural antibodies think the
kidney transplant. new tissue Is a foreign Invader and attacks; careful pre-operative matching helps limit
the degree of this attack. The mostimportant match is via the ABOblood group type -
the blood group must match orrejection is fast and aggressive. Next, the body's HLA
(human leukocyte antigen) system should be a close a match as possible, although it
"Patients ore doesn't need to be perfect. incorrect matches here can lead to rejection over longer
periods of time. After the operation, patients are started on anti-rejection medicines
monitored for which suppress the host's immune system (immunosuppressants such as Tacrolimus,
the rest or, A2athioprine or Prednisolone). Patients are monitored for the rest of their lives for
signs of rejection.These immunosuppressants aren't without their risks - since they
their lives ' suppress the body's natural defences, the risks of infections and cancers are higher.

0 57
 stigiol organs

Why have humans and other animals stopped using certain

organs and functions which were once crudal for survival?
Charles Darwin Is one of history's much as other creatures; some of our physical
most famous naturalists. Living in attributes and behavioural responses are
the 19th Century, he became functional in other animals, but they do not
celebrated for his theories on seem to be of any benefit to us. These
evolution. In his seminal work On The Origin Of evolutionary remnants that no longer serve any
Species he described how similar animals were purpose are called vestigial organs, though this
likely to be related by common ancestors, can apply as much to behaviour and other body
rather than be completely unre lated. As structures as it does to actua I organs.
subsequent generations are born, traits and Evolution has also adapted some existing
features that did not bring a survival benefit to features to help us in new ways, in a process
that species were eliminated. That, in a known as exaptation. For example, birds' wings
nutshell, is the theory of evolution. not only help them to fly but keep them warm
As a consequence, some organs and traits left too. These changes may take thousands of years
in the body lose their function and are no longer to develop, and in some cases the original role
used. This applies to modem human beings as is eventually eliminated altogether.

Appendicitis In focus
What happens when your appendix gets Infla med?

Surgery Progression
OurlngsurgerytoremO\Ie The Inflammation can
theappendbc, the surgeon lead to perloratlon of the
Ues off the base to prevent appendix and
bowel contents leaking, lnflammatlon of
and removes the whole surrounding llssues.
appendix organ The pain worsens and
then localises to lhe
lower right-hand side of
the abdomen.

Blockage
Ablocl<age. caused by either
atinypleceofwasteor
swoUen lymphatic tissue In
the bowel wall. causes
appendix swelling.

Inflammation
Beyond the blockage.
Inflammation sets ln. wblch
causeslntenseabdomlnalpaln.

058
THE sizE7.6 x 12.7 x 2.5cm wEIGHT200g
STATS
THE SPLEEN ~~6~1JLP 75°/o WJt% PULP 25% ~~~~~~~GT -5o/a
I•U•JW•1!113N•IW Around 15 per cent of us hove an extm spleen - a small sphere close to but separate from the principal organ

Perhaps not as welllmown as famous organs like the heart,

the spleen serves vital functions that help keep us healthy ..-------- Location
The spleen sits mdemeath the
9th, 10th and llth rils (below
The spleen's main functions are to remove old Inside the spleen the diaphragm} on the
blood cells and fight oHinfectlon. Red blood cells left-hand side of the body,
have an average IUespan of 120 days. Most are We take you on o tour of the
major fecjtures in this ofiPn- which provides it with some
created from the marrowoflong bones, such as overlooked organ protection against knocks.
the femur. When they're old, It's the spleen's job to ldentHy
them, filter them out and then break them down. The smaller
particles are then sent bacl< Into the bloodstream, and either Hilum - - - - - - . .
recycled or excreted rrom other parts of the body. This takes The entrance to the spleen, Splenic vein
place in the 'red pu lp', which are blood vessel-rich areas of the this is where the splenic artery The waste products
spleen that make up about three-quarters oflts structure. divides into smaller branches from filtration and
and the splenic vein is formed pathogen digestion
The remainder Is called 'white pulp', which are areas filled
from its tributaries. are returned to the main
with different types of immune cell (such as lymphocytes). circulation via this vein
Theyfilteroutand destroy foreign pathogens. which have fur disposal
invaded the body and are circu lating in the blood. The white Spleric artery
pulp breaks them down into s maller, harmless particles. The spleen receives a bbxl
The spleen Is surrounded by a thin, fragile capsule and sols stJpply via ll>s artery,
prone to injury. It sits beneath the lower ribs on the left-hand which arises from a branch

side of your body, which affords It some protection, but car of the aorta called the
coeiactnd.
crashes, major sports impacts and knife wounds can all
rupture the organ. In the most serious cases. blood loss can
endangerthe person's life, and In these situations It needs to
be removed by a surgeon. Since this reduces the body'sabUity
to fight infections, some people will need to take antibiotics to
boost their immunity for the rest ofthelr lives.

The immune system

Although the red blood thai nows lhrough our bodies gets all the
glory. the transparent lymphatic nuld tsequallytmportant. It has Its
own body-wide networic whJcll follows blood vessel flow closely and
allows for the transport ofdlgested lat.$. Immune cells and more...

Spk!en Adenoids
Oneofthemasterco-ordlnators These are part of!he tonsillar
thatstavesofflnlecttonsand system that are onlypresen!ln
flltersold red blood cells. II children up until the age of nve;
contains anumberof In adults !hey have disappeared.
lymphocytes that recognise and They add an extra layer of
destroy Invading pathogens defence In our early years.
present In the blood as It flows ...................._........._.....
................
._ ~
!!
through the spleen. Bone marrow
....,...·-··-·····0<--000.000..........._._..... Thtsformsthecentral, Oexlble ~--~~------------_.~------------------_j ~
Thymus part ofour long bones (eg femwj.
A small organ thai sits justabove Bone marrow IS essentfal as It
the heart and behind the produces our key ctrculatfng
sternum. II teaches cells, Including red blood cells, Whitepulp ~ . - - - - Splenic capsule
T4ympbocytestoldentifyand whlre blood cells and plalelets. MaiOOg up roughly a The capsule provides some
destroyspedfic foreign bodies. The white blood cells mature ~of the spleen. protection. but it's tiWl
ltsdeYelopmentlsdtrectly Into <llfferent rypes teg the-""" is and relatillely weak. Strong
n!lated to hormones In the body lymphocytes and neutropbfls~ \/\/here wntebbxl blows or lcrife womds can
so It's only present untU puberty whlthserveas the basis of the eels identify and easiy .....,rure it and lead to
end.$;adtdtsdon'tneedone. human lntmunesystem. destroy- type of if~HhreatEI oi 19 bleeOOg.

----------·-
Tonsis -----
--------------
Lymph oodes
irorading pathogens.

Tbesearemassesollymphold These are smalljabout v:mJ

tissue at the back ol the throat o#nlspherical nodes that are
and can beseenwben the mouth paclcedwllh~and
......_____ SintiSOid
Iswide open. Tbeyform the first lymphocytes to defend against Redptjp - ---
line oldefenceagalnsllnhaled foreign agents. Tbeseareolten Fonning app~axi ooately Simiar to those fomd ., the
foreign patbogens. although llnl<ed In chains and are three-quarters of the IM!r, thesecapilaries alow
they can become Infected prevalent around the bead, spleen, the red pulp is fur the easy passagP. of
themselves, causing tonsUUtls. neck. axillae jarmpltsland groin. \/\/here red blood cells are large eels into the splerjc
fitered and bro4<en down. tissue fur processing.

059
 umon digestive system

How does food get

turned into energy?
... The digestive system Is a group of org;ms that
• • process food into energy that the human body
can use to operate. It Is an Immensely complex large intestine

' ~
system that stretches all the way between the
mouth and the anus.
Primary organs that make up the system are the mouth,
oesophagus, stomach. small lntest.lne, large Intestine and the
The colon, as the large
intestine is also known, is
wllere waste material will
be stored until expeled
fn:m the digestille system
anus. Each organ has a different function so that the maximum tlwough the recwm.
amount of energy Is gained from the food, and the waste can
be safely expelled from the body. Secondary organs, such as
the liver, pancreas and gall bladder, aid the digestive process
alongside mucosa cells, which line all hollow organs and
produce a secretion which helps the food pass smoothly
through them. Muscle contractions ca lied peristalsis also help
to push the food throughout the system.
The whole digestive process starts when food is taken Into
the body through the mouth. Mastication (chewing) breaks
down the food into smaller pieces and saliva starts to break Small intestine
starch in these pieces offood lntoslmplersugarsas they are Nu1rlents that have been
swallowed and move Into the oesophagus. Once the food has released from food are
passed through the oesophagus, It passes Into the stomach. It absoobecl into the blood
can be stored in the stomach lor up to four hours. The stomach stream so they can be
will eventually mix the food with digestive juices that It transported to w11ere they ate
produces, and this breaks down the food further into simpler needed in the body through
the small intestine waM.
molecules. These molecules then move Into the small intestine Further breaking down occurs
slowly, where the final stage of chemical breakdown occurs here with enzymes from the
through exposure to juices and enzymes released from the liver and pancreas.
pancreas, liver and glands In the small intestine. Nutrients are
then absorbed through the Intestinal walls and transported
around the body through the blood stream.
After all nutrients have been absorbed from food through the
small intestine, resulting waste material, lncludlngHbreand
old mucosa cells, Is then pushed Into the large lntestlnewhere it
How
will remain untll expelled by a bowel movement

"Nutrients ore then

absorbed through the
intestinal walls ond Rectum
transported around Many different organs
This is wllere waste
material ('-:es) exits

the body" ore Involved in the the digestiw system.

digestion process
060
 •• •
• •• ••
•• •• • ••
Complete digestion •• The stomach can ••• We use P.ints ol ~':.trough
STOP 1
takes time!
•• Some food
• for thought...
:2• • hold two litres
:3
• ••• saliva a Clay!
4 •
•
••

s
roduction
age

FACTS Generally, it can take between

24and 12 hoLrS for the food
you eat to be fuUy digested,
meaning you're constantly
:
•
•
••
An average human male will
constJme approximately 50
tons of food Wring his lifetime.
That's the eqlivalent of ten
•
•
•
•
•
•
The stomach wil normally
feel fulwhen it reaches a
capacity of one litre, but
ultimately it can stretch up
••
•
•
••
•
Up to four pints of saliva can be
produced by an .,dividual each
day and it helps to digest food
and protect teeth and tissue
!
:
•
••
•
Enzymes are crucial for
~.but as we age,
enzyme production red.K:es ... at
70a person may produce half
DIGESTION digestng food! • Afri::an elephants. • to two litres. • inside the mouth. • what theydidat20.

ltU•JU•11J!3N•IW The human digestive system is between 20 to 30 feet long!

- - Mouth
This is where food enters the body a nd first gets broken into
more manageable pieces. Saliva is produced in the glands
and starts to break down starch in the food.
How our : ~

/
Oesophagus
The oesophagus passes the food
into the stomach. At this stage, it
has been broken down through
Oesophageal
sphincter
This is the control
- d
work?
The stomach is one of the most crucial
valve for letting food
mastication and saliva will be
breaking down starch.
into the stomach.
organs within the digestive system
Corpus body - ....J The stomach's function is to break down food
This is where stomach into simple molecules before it moves into
acid is s ituated. the small intestine where nutrients are
consequently it is absorbed. The organ actually splits into four
where food is broken
distinct parts, all of which have different
down into molecules
that the small intestine
functions. The uppermost section is the
can then process. cardia, where food is first stored, the fundus
is the area above the corpus body, which
makes up the main area of the stomach
where food is mixed with stomach add. The
final section is the antrum, containing the
pyloric sphincter, which is in control of
emptying the stomach contents into the
small intestine. Food is passed down into the
stomach by mucosa and peristalsis through
Mucosa the oesophageal sphincter, and then mixed
These cells lineal of the
stomach to aid rr>Clii<!Oleflt of in the stomach withacidsandjuices by
food throughout the organ. muscle contractions.

Stomach - - - - - ' Duodenum - - - - ,

This is where food is broken
down to smaller molecules
which can then be passed into
The area at the top of the
small intestine, this is
where most chemical
•
How the
ne
the small intestine. Stomach breakdown occurs.
acid and enzymes produced
by the stomach aid this. I
The intestine is a crucial
part of the digestive
that is heavily
L .............

involved in breaking
down and absorbing
nutrients released from
ingested food
The intestine splits into two distinct parts,
the small intestine and the large intestine.
The small intestine is where the food goes
through final stages of digestion and
nutrients are absorbed into the blood stream,
the large intestine is where waste is stored
Rectum until expelled through the anus. Both the
This is where small and large intestines can be further
waste is stored
briefly ll1til it divided into sections, the duodenum,
is expelled by jejunum and ileum are the three distinct
the body. sections of the sma II intestine and the
cecum, colon and rectum are the sections of
the large intestine. As well as storing waste,
the large intestine removes water and salt
from the waste before it is expelled. Muscle
contractions and mucosa are essential for the
Villi intestine to work properly, and we see a
These cells are shaped like fingers
and fine the smaJI intestine to increase variation of mucosa, called villi, present in
Sll'faoe area for nutrient absorption. the lower intestine.

061
 liver explained

The liver is the largest internal organ in The liver Is the body's main powerhouse, producing
The human liver is the

'
~

• the h11 rna n body and amazingly has over 500 andstorlngglucoseasa keyenergysource.ltisalso
ultimate multitasker - • different functions. In fact, it is the second responsible for breaking down complex fat molecules and
most complex organ after the brain and is
J
building them up Into cholesterol and triglycerides. which
it performs many lnUinslca lly involved in almost every aspect of the body's the body needs but In excess are bad. The liver makes
different functions metabolic processes. The liver's main functions are
energy production, removal of harmful substances and
many complex proteins, Including clotting factors which
are vita l in arresting bleeding. Bile, which helps digest fat
all at the same time the production of crucial proteins. These tasks are carried in the intestines. is produced In the liver and stored in the
out within liver cells, called hepatocytes, which sit In adjacent gallbladder.
without you complex arrangements to maximise their overall The liver also plays a l<ey role In detoxifying the blood.
even asking efflclency. Waste products, toxins and drugs are processed here into

The•
~"~~reCIIignlon

Two halves ------..

The live- is anatomicaly spit
into two halves: left and right.
There are foor lobes, and lhe
right lobe is lt1e largest. ::.....__ _ _ _ Eight segments
The gallbladder - - :;...- Ftnctionally, ltlere are
The gatiodder and._ eicj1t segiiiE'I Its cl the
are intrnately related. Bie. a-,IMlich are based
wiOch ~ <igest ful, is upon lt1e <istriJution
pnxb:ed., lt1e IM!r and a
of veins ail ling
stored ., lt1e g;albladde<. these segll M3 Its.

The common bile duct

This duct is smalt but vital in
lt1e tunan body. It carries bile
from lt1e iver and gallbladder
into tile duoder<Jm where ~
helps digest fat

Feel your liver

Take a drep breath in and feel
just under lhe right lower
edge of your ribs- in some
people lhe lower edge of the
liver can be felt. - - - - - -
The portal triad
The common bile duct.
hepatic artery and
hepatic portal vein form
lt1e portal triad, which
are lt1e vital inflows and
outflows fc< this iver.

- -1, . . - - - - - - - - - - Digestion
+--+-....._-+-- The biggest organ Once nutrieols from food have
The._ is tile largest ot been absorbed., tile smal
lt1e internal organs, sitting in lt1e intestine, they are transported

right -quadrantoiltleabdomen,
just under lt1e rib cage and attached to
~-------­ to tile iver via tile hepatic
portal"""' (not shown here)
tile underside ot lt1e <iaplyagm fc< energy production.

062
 •
•• •• •• •
•
•• Uver transplants • • •
Ice cold liver : Maximising numbers : Largest organ in the body : Greek mythology
STOP 1 Polar bear liver is an incredibly
rich source ol vitarrin A ..
•
•
••
2 In the UK 600·700 liver
transplants are performed
•• 3
:
W<JYS around the shortage of
donor-li'-Ers include splitting an
:• 4
•
The liver is the largest internal
organ in the human body and in
•!• 5 Wtse Trtan Prometheus
was chained for etemity to a

FACTS so much so that Arctic

explorers have actually died
from eating it, as it can cause
•
•••
•••
each year. The donor li\ler
can be preserved in a solution
for up to 24 hours before it
:
••
••
adult liver in hatf and givi'lg it to
two chilli-en, and live.cfonor
transplantation (a portion of a
!
••
••
most arWnals' bodies too. It
typ«:ally has the same shape as
a human's, except in snakes
!
••
••
rock in the Caucasus, where
an eagle would eat at his liver
and each day the liver would
LIVER extreme vitamin A poisoning. is transplanted. • relative·s iYer is transplanted}. • where it is elongated. • bereoewed!
• • • •

ltU•JU•11J!3N•IW The liver con regenerate itself. If up to 75 per cent of the liver is removed. it con grow bock to restore itself
forms which are easier for the rest of the body to use or
excrete. The liver also breaks down old blood cells,
produces antibodies to fight infection and recycles
hormones such as adrenaline. Numerous essential
vitamins and minerals are stored in the liver: vitamins A,
A high demand
The liver deals with a massive amountofblood. branches from
n
carrying oxygen which
D, E and K, iron and copper. It is unique because it has two blood supplies. 75 the liver needs to produce this energy. The blood
Such a complex organ is also unfortunately prone to per cent of this comes directly from the flows in tiny passages in between the liver cells
diseases. Cancers (most often metastatic from other intestines (via the hepatic portal vein) which where the many metabolicfunctions occur. The
sources), infections (hepatitis) and cirrhosis (a form of carries nutrients from digestion, which the liver blood then leaves the liver via the hepatic veins
fibrosis often caused by excess alcohol consumption) are processes and turns into energy. The rest comes to flow into the biggest vein in the body- the
just some of those which can affect the liver. from the heart, via the hepatic artery Iwhich inferior vena cava

"The liver also breaks

down old blood cells
ond recycles hormones Liver
such os adrenaline" The functional unit which
3. Sinusoids - - - . , performs the liver's tasks
These blood filled
chamels are lined by The liver is considered a 'chemical factory; as It
hepatocytes and provide forms large complex molecules from smaller
the site of transfer of
1. The lobule ones brought to it from the gut via the blood
molecules between blood stream. The functional unit of the llver Is the
This arrangement of blood
and fiver cells. lobule- these are hexagonal-shaped
vesseis, bile ducts and
hepatocytes form the structures comprising of blood vessels
functional unit of the fiver. and sinusoids. Sinusoids are the
speciallsed areas where blood
comesintocontactwith the
2. The hepatocyte hepatocytes, where the liver's
These highly active cells biological processes take place.
perform all of the liver's
key metabolic tasks.

4. Kupffer cells
These specialised eel s sit
9. Central vein --. within the sinusoids and
Blood from sinusoids, now destroy any bacteria which
containing all of its neo.v are contaminating blood.
molecules, flows into
central veins which then
flow into larger hepatic
veins. These drain into
the heart via the
inferior vena cava.
r - - - 5. Hepatic
artery branch
Blood from here supplies
oxygen to hepatocytes and
carries metabolic waste
which the liver extracts.

- - - 6. Bile duct
gal Bile, wnch helps digest fat, is
made in hepatocytes and
Bile, a dark green slimy liquid, is produced in the secreted into bile ducts. It then
hepatocytes and helps to digest fat. It is stored in a flows into the galllladder for
reservoir which sits on the under-surface of the liver, _,.......
storage before being
secreted into
to be used when needed. This reservoir is called the
the duodenum.
gallbladder. Stones can form in the gallbladder
(gallstones) and are very common, a !though most
don't cause problems. In 2009, just under 6o,ooo
gallbladders were removed from patients within the
NHS makingitone of the most common operations '------ 7. Portal vein
performed; over go per cent of these are removed via 8. The portal triad This vein carries nutrient·rich blood
keyhole surgery. Most patients do very well without The hepatic artery, portal vein and bile duct are known as directly from the intestines, which
their gallbladder and don't notice any changes at all. the portal triad. These sit at the edges of the liver lobule flows into sinusoids for conversion
and are the main entry and exit routes for the liver. into energy within hepatocytes.

063
 Structure of the
small intestine
Examine the anatomy of this vital
organ in the human digestive tract

Lumen - --------..
This is the space inside the
small intestine in which the
food travels to be digested ~~-.::=:::;,j
and absorbed .

• Mucosa - - - - - - - -

or1 Mucosal folds - _J

The internal lining of the
small intestine where the
plicae circulares (mucosal
folds) and villi are situated.

sma intestine These line the small

intestine to Increase
surface area and help
push the food on Its way
Submucosa - - - - - -
This supports the mucosa
and connects it to the layers

Crucial for getting the nutrients we need from the by creating a valve-like
structure, stopping food
of muscle (muscularis) that
make up the exterior of the

food we eat, how does this digestive organ work? travelling backwards. small intestine.

The small intestine is one of the turning food into an amino add state. While - and mucosal folds line the passage and
most Important elements of our the duodenum is very important in breaJd ng increase the surface area dramatically to aid
digestive system, which enables us food down, using bile and enzymes from the this process. The ileum is the final section of
to process food and absorb gallbladder, liver and pancreas, it is the the small bowel and serves to catch nutrients
nutrients. On average, it sits at a little over six shortest element of the small bowel, only that may have been missed, as well as
metres (19.7 feetllong with a diameter of 2.5-3 averaging about 30 centimetres (tLB inchesl. absorbing vitamin Bu and bile salts.
centimetres (1-1.2inches1, and it's made up of The jejunum follows the duodenum and Its Perista Isis is the movement used by the small
three distinctive parts: the duodenum. primary function is to encourage absorption of intestine to push the food through to the large
jejunum and the ileum. carbohydrates and proteins by passing the bowel. where waste matter is stored for a short
The duodenum connects the small intestine broken-down food molecules through an area period then disposed of via the colon. This
to the stomach and is the key place for further with a large surface area so they can enter the process is generated by a series of muscles
enzyme breakdown, follow! ng the stomach bloodstream. Villi - small finger-like structures which make up the organ's outer wall.

064
 THE LENGTH 6m DIAMETER 2.5•3cm tg.wA JsT~~682°
1
1-4 hours
STATS
SMALL BOWEL suRX~f~ 250m ~~Yfi.JT As~<6~ttloN 90°/o ~~~~A~~~ 10-40
2 0 1

I•U•JW•1!113N•l!i'i> The small intestine is actually Ianger th:Jn the large intestine, but is sa called because af its mrrawer diameter

Serosa
This protective outer layer stops What exactly are nutrients?
the small intestine from being There are three main types of nutrient that we process in the
damaged by other organs. body: lipids (fats), carbohydrates and proteins. These three
groups of molecules are broken down into sugars, starches,
fats and smaller, simpler molecule elements, which we can
absorb through the small intestine walls and that then travel in
the bloodstream to our muscles and other areas of the body
that require energy or to be repaired. We also need to consume
and absorb vitamins and minerals that we can't synthesise
within the body, eg vitamin 812 (prevalent in meat and fish).

Fat Carbohydrate

Protein
Nutrients
Nutrients move through Blood vessels
These sit close to the
the t ube-like organ to be
diffused into the body, small intestine to
mainly via the bloodstream. allow easy diffusion
of nutrients into the
bloodstream.
A closer look at villi
Villi What role do these little f inger-like
Villi are tiny finger·like prot rusions play in the bowel ?
structures that sit all over
_j t..________ Longit udinal the mucosa They help
increase the surface area
Epithelium
(epithelial cells)
Lacteal
The lacteal i.s a
muscle layer massively, alongside the These individual cells that Mucosa lymphatic capillary
This contracts and extends mucosal folds. sit in the mucosa layer The lining of the small that absorbs nutrients
Circular to help transport food with are where individual intestine on which that can' t pass directly
muscle layer the circular muscle layer. microvilli extend from. villi are located. into the bloodstream.
This works in partnership
with the longitudinal
muscle layer to push the
food down via a process
called peristalsis.

M icrovilli - - - - - ,
These are a mini version
of villi and sit on villi's
individual epithelial cells.

Capillary bed
These absorb simple
sugars and amino acids as
they pass through the
epithelial tissue of the villi.

065
 Inside the thoracic cavity
It may not look like it at first glance,
but there are more than two dozen
bones that make up the ribcage ...

,.. ..

Clavicle ----J
Also known as the
collarbone, this pair of
long bones Is a support
between the sternum
and the shoulder blades.

True ribs ----~

Rib pairs one through
seven attach to the
sternum directly via
a piece of cartilage.

uman
•
r1 False ribs ----.~
Rib pairs eight through
ten connect to the
sternum via a structure
made of cartilage linked
Ribs are not merely armour for the organs to the seventh true rib.

inside our torsos, as we reveal here...

. -
=a'
•
The ribcage- also known as the
• thoracic cage or thoracic bas.k et- is
easily thought of as just a
rather, most of them do. Rib pairs one through
seven are called ' true ribs' because they attach
directly to the sternum. Rib pairs eight tnrough
... framework protecting your lungs, ten attach indirectly through other carti !age
heart and other major organs. Although that is structures, so they're referred to as 'false ribs'.
The final two pairs - the 'floating ribs'- hang
one key function, the ribcage does so much
more. It provides vital support as part of the unattached to the sternum.
What are hiccups?
Hoccupping - known medically as singultus, or
skeleton and, simply put, breathing wouldn't Rib fractures area common and very painful synchronous doaphragmatic flutter (SOF) - is an
be possible without it. injury, with the middle ribs the most likely involuntary spasm of the diaphragm that can
All this means that the ribcage has to be ones to get broken. A fractured rib can be very happen for a number of reasons. Short·term
causes include eating or drinking too quickly, a
flexible. The conical structure isn't just a rigid dangerous, because a sharp piece could pierce sudden change in body temperature or shock.
system of bone- it's both bone and cartilage. the heart or lungs. There's also a condition However, some resear have suggested
The cage comprises 24 ribs, joining In the bac.k called flail chest. in which several ribs break that hiccupping in premature babies -who tend
to hiccup much more than fuft·term babies - is
to the 12 vertebrae making up the middle of the and detach from the cage, which can even be due to their underdeve lungs. It could be an
spinal column. The cartilage portions of the fatal. But otherwise there's not much you ca n evolutionary leftover, since hiccupping in humans
do to mend a fractured rib other than keep It is simolar to the way that amphibians gulp water
ribs meet In the front at the long, flat three-
and aor into their golls to breathe.
bone plate called the sternum (breastbone). Or stabilised, resting and giving it time to heal.

066
 •
•
•• •• ••
• : Fractures :• Sunken chest •• Tasty ribs
F1exible cage • Endless ribs
STOP l in normalad<Jits, the ribcage
expands by three to five
••
••
•
2 Snakes can have up to 400
vertebrae, with al but the tail
•
:3 Thesewnthand the tenth : 4 congenital
! are the ones most likely to get :
Pectusexcavaturntsa
ribs
deforrrity caused by
5 ••
•
••
lar-ge carniVores, such as lions,.
often head towards the

FACTS centimetres (L2 to two inches)

when you lnhale. ln an average
breath at rest.~ take In about
•••
•
••
Vl!rtebrae havW1g a par of ribs.
Each rib is attached to a belly
scale which Is a key part of
•
•••
••
broken in humans, while the
fii'St pair is rarely fractl.l'ed
becatJse of Its location behind
•
•••
••
aboormalgrowth of the ri>cage, :
resufting in a caved-in ••
appearance that can also affect •
•
ribcages of their kills first to
dwoor both the rib meat and
rich organs, like the heart,
RIBCAGE TRIVIA 500 mil61itros (0.9 p;nts) of air. • haYti snakes slither. • thedavide. • the heart and lungs. • which ar'E! encased within.
• • • •

ltU•JU•11J!3N•IW The condition known os flail chest is fotol in almost so per cent of cases

, - - - - - - - - - - - - - - - - - - - Manubrium
This broadest and thickest part
of the sternum connects with Breathe in,
the clavicles and the cartilage
for the first pair of ribs. breathe out...
Consciously take in a breath, and think about the
fact that there are t en different muscle groups
working t ogether to make it happen. The
muscles that move the ribcage itself are the
intercostal muscles. They are each attached to
the ribs and run between them. As you inhale,
the external intercostals raise the ribs and
... sternum so your lungs can expand, while your
diaphragm lowers and flattens. The internal
intercostals lower the ribcage when you exhale.
This forces the lungs t o compress and release air
(working in tandem with seven other muscles). If
you breathe out gently, it's a passive process
that doesn't require much ribcage movement.

Inhalation Contraction
As you inhale, the The diaphragm contracts by
'------"'-'-"...:..,..:;_----:__;,~-'---- Sternal angle intercostal muscles moving downward, allowing
This is the angle formed by contract to expand the lungs to fill with air.
the joint between the and lift the ribcage.
manubrium and the body,
often used as a sort of
'landmark' by physicians.

Body
The main body of the
sternum (breastbone) is
almost flat, with three
ridges running across its
surface and cavities for the
cartilage attaching to rib
pairs three through seven .

.,__ _ _ Floating ribs

(not shown)
Pairs 11-12 are only attached
to the vertebrae, not the
Xiphoid process sternum, so are often called
This exten.sion from the the floating, or free, ribs.
sternum starts as cartilage,
but hardens to bone and
fuses to the rest of the
breastbone in adulthood.

Ribs in other animals

Most vertebrates (ie animals with ribs overlap one another with hook·like
backbones) have a ribcage of sorts - structures called uncinate processes,
however, ribcages can be very which add strength. Frogs don't
different depending on the creature. have any ribs, while turtles' eight rib
For example, dogs and cats have 13 pairs are fused t o the shell. A snake's
pairs of ribs as opposed to our 12. 'ribcage', meanwhile, runs the length
Marsupials have fewer ribs than of its body and can comprise hundreds
humans, and some of those are so tiny of pairs of ribs. Despite the variations
they aren't much more than knobs of in appearance, ribcages all serve the Exhalation
bone sticking out from the vertebrae. same basic functions for the The intercostal muscles Relaxation
Once you get into other vertebrat es, most part: to provide support and relax as we exhale, The diaphragm relaxes,
the differences are even greater. Birds' protection to the rest of the body. compressing and moving upward to force
lowering the ribcage. air out of the lungs.

067
e pancreas up-close
 336 BCE 1st century CE 1642
KEY The GrC!<'k Matornist The name 'pancnas' is giwn, The pancreatic duet Is Gemlan scientists l't'l'l"'IYe The flfSt l'r'lOdem hl.l'nan
DATES wl1o w~l fH'SI diSCCM!I'
thepancroas -
rnerilg 'all fle-sh', as it's
believed to......., solely as a
found In Padua, Italy. It Is the pancreas In a dog and
nam<!d aile< ~• discolle<er: induce diabetes, proving
panaeatic transplant Is
perfonned in the USA on a
PANCREATIC PAST Ho<ophllus -Is bam. cushioning, protective fat pad. the clJct of WOsun!l. an iiTOiutilblc link. 28-year-old female patlert.

l•U.1\1•li i :'W•mJP In the UK. Bo per cent of acute pancreatitis cases ore caused by gallstones or excessive alcohol ingestion

What brings on diabetes?

Diabetes is a condition where a other disorders of the pancreas.
person has higher blood sugar than Inflammation of the organ (ie acute
normal. It is either caused by a pancreatitis) causes severe pain in
failure of the pancreas to produce the upper abdomen, f orcing most
insulin (ie type 1, or insulin· people to attend the emergency
dependent diabetes mellitus), or department as it can be life
resistance of the body's cells to threatening. In contrast. cancer of
insulin present in the circulation (ie the pancreas causes gradually
type 2, or non-insulin-dependent worsening pain which can often be
diabetes mellitus). There are also mistaken for other ailments.

Beta cells
It is the beta cells
within the islets of
langerhans which Insulin released
control glucose The vesicle releases its
levels and amount stored insulin into the
of insulin secretion. blood capillaries
tlvough exocytosis.

High glucos e
When the levels of
glucose within the
bloodstream are high.
the glucose wants to Calcium
move down i ts diffusion effects
gradient Into the cells. The calcium
causes the
vesicles that
store insulin to
move towards
the cell wall.
Does the vary in
humans and animals?
Every vertebrate animal has a pancreas of some form,
meaning they are all susceptible to diabetes too. The
arrangement, however, varies from a-eature to creature. In
humans, the pancreas is most often a single structure that sits
at the back of the abdomen. In other animals, the arrangement
varies from two or three masses of tissue scattered around
the abdomen, to tissue interspersed within the connective
tissue between the bowels, to small collections of tissue within
the bowel mucosal wall itself. One of the other key differences
is the number of ducts that connect the pancreas to the bowel. GLUT2 De polarisation '--- Calcium channels
In most humans there's only one duct. but occasionally there This is a glucose· The metabolism of glucose Changes in potassium
may be two or three - and sometimes even more. In other transporting channel, leads to changes in the levels cause voltage-gated
animals, the number Is much more variable. However, the which facilitates the polarity of the cell wall calcium channels to open in
function is largely similar, where the pancreas secretes uptake of glucose and an increase in the the cell wall, and calcium
digestive enzymes and hormones to control blood sugar levels. into the cells. number of potassium ions. ions to flow into the cell.
 human bladder
Wben you've got to
go, you've got to go. ..
but reaUy our bodies THE COMPLETE
are reactln& to our
bladders' direction
URINARY SYSTEM
Kidneys
Thekicftys
un...........-ded
substances in the
blood into urine.

Ureters
Uretencany
urlnefrcm
the kicftys to
the bladder.

Urethra
Thelfttlnruns
frcm the bottom
olthebladderto
the outside wor1d.

I
Bladder
As a key part of the urinary system, the bladder This muscular
bag generaly
is crucial to removing waste from your body holds around a
pint of urine.
The bladderlsoneofthe keyorgansln the urinary the bladder becomes full, or nearly lull, the nerves in the
system and It stores urine following productlon by bladder communicate with the brain, which In turn Induces an
the lddneysuntll the body can release lt. urge to urinate. This sensation will get stronger If you do not go
Urine Is a waste substance produced by the - creating the 'bursting lor a wee' feeling that you can
kidneys as they filter our blood of toxins and other unneeded occasionally experience. When ready to urinate, both the
elements. Up to 150 lltres (40 gallons} of blood are filtered per day internal and externalsphincters relax and the detrusor muscles
by your kidneys, but only around two lit res (0.5 gallons} of waste in the bladder wall contract in order to generate pressure,
actually pass down the ureters to the bladder. forcing urine to pass down the urethra and exit the body.
Urine travels down the ureters and through the ureter valves, As well as telling you when you need to pass fluid, the urinary
which attach each tube to theorganand prevent any llquid system also helps to maintain the mJnera land salt balance In
passing back. The bladder walls, controlled by the detrusor your body. For instance, when salts and minerals are too highly
muscles, relax as urineentersandallow the organ to Hll. When concentrated, you feel thirst to regain the balance.

For the bladder to work correctly, urlnewithoutcontrol It is often caused pressure (eg while coughing. laughing
several areas within It must all functlon by involuntary spasms by the detrusor orsneeztng). Thlsklndoflncontlnence
properly. It is most commonly the muscles which can be a result of either is most common in the elderly.
failure of one of these features that nervous system problems or infections. One modem remedy Is a preventative
leads to incontinence. Another type is stress incontinence, implant that has been developed to
Acommon type of urinary caused when the external sphincter or replace post-event Incontinence pads.
incontinence Is urge incontinence. ThIs pelvic floor muscles are damaged. Tbis This comes in the form ofa collagen-
is when an indlvidual feels a sudden means urine can accidentally escape, based substance Injected around the
compulsion to urinate and will release especially if the pelvic Door is under urethra in order to support it.

070
 •
•
•• •• •••
• • •
• • • •
Urethras- all the same? •• Getting the urge •• Duration •• Can you drink urine? •• How to keep healthy
STOP 1Women's urethras are much
shorter than men's due to
!
;
2 Theurge. to urinate normally
comes when the bladder
:3
;
Urine can stay in the bladder- :
for anywhere between one to ;
4 Of course, this would not
generaDy be recommended in
;5
;
It's advised to drink around 1-1.5
litres (2.1-3.1 pints) o f water a

FACTS differing genitalia. Women ate:

consequently far more likely to
get bladder/urine Infections
••

•
•
••
reaches between 25-50% of
full volume to avoid reaching
100% when lni/Oiuntary
•••
••
•
eight hours befor-e excretion.
TM tme it temains there will •
•
vary de:pooding on the amount:
•• oonnal circumstances, but
yes, urine is completely sterile
- it contains no bacteria,
••
•
••
•
day. This will keep the urinary
system working most effectively.
We k>se more water than this
B DERS becaLJSe of this. • urination will occur. • of liquid consumed. • viruses or fungi. • but obtain some from food.

I•U•JU•111!3N•IW Everyone's bladder differs slightly in size. The overage maximum copodty is between 6oo-Booml [1-3-l.lPt]

Inside the bladder •

IS
How this argon acts as the middleman
•
between your kidneys and excretion Bla~~
muscles)
1nade
The detrusor muscles
make up a layer of the
up of?
bladder wall. These Ahuman bladder usually holds around
FULL 1+ - - - - - - Ureters - - - - - --.:
These tubes link the kidneys
muscles cause the wall 350 millilitres (0.7 pints) of urine, though
BLADDER and the bladder, transporting
the urine for d isposaL
to relax and extend as
urine enters, while
male bladders can typically hold slightly
more than those of females. Urine is
nerves situated in the
Ureter valves wall m easure how full
made up of urea, the waste by-product
These sit at the end of the bladder is and will
the body forms while breaking down
the ureters and let signal to the brain protein across the body. The kidneys will
urine pass into the when to urinate. filter this out and pass it with extra water
b ladder w ithout letting
to the bladder for expulsion. Other waste
it flow back.
products produced or consumed by the
body that pass through the kidneys will
alsoexltthe bodyvia this route.
--~"'---- Internal
Lrethral sphincter 1}'plcally, urine is made up of 95 percent
The internal sphincter is water and 5per cent dissolved or
controlled by the body. It suspended solids Including urea, plus
stays dosed to stop urine chloride, sodium and potassium ions.
passing out of the body.

Pelvic floor muscles ----. External urethral

These hold the b ladder in place,
sphincter
(distal sPhincter)
URINE
and sit arOlBld the urethra
This sphincter is controlled
CONTENTS
stopping unintended urination.
by the individual, and they
control w hether to open or
Uric acid
0.6g ---.
close the valve.
Bicarbonate

Pd •sim ions
3.2g

EMPTYING Sodium ions

4.lg
BLADDER
01loride ions
6.6g

&~~+--- Bladder wall

(~~
Internal urethral ---~~;;.::5~~:;:] muscles)
sphincter ~ These m uscles contract
This relaxes when the to force the urine out
of the bladder.
Urea
body is ready to expel 25.5g
the waste liquid.

~~!~thrai ------J
~stal sphincter) ,·;~t'+"-.----------- Urethra
This also relaxes for the urine Urine travels down this
to ex~ the body. passageway to leave the body.

071
 uman pregnancy explained

Nine months of change and growth

.
Pregnancy Is a unique pe.rlod Ina woman's life thatbringsaboutphysicaland

a
- . emotional changes. When It occurs, there !san Intricate change the balance of
the oestrogen and progesterone hormones, which causes the cessation of
~
in

menstruallon and allows the conditions In the uterus (womb) to become suitable
for the growth of the fetus. The lining of the uterus, rather than being discharged, thickens
and enables the development of the baby.
At first, it !sa collecllon of embryonic cells no bigger than a pinhead. By week four the
embryo forms the brain, spinal cord and heartlnsldethe newlyOuid-filledamnloticsac.
Protected by this cushion offluid, It becomes recognlsably human and enters the fetal stage
by week eight.
Many demands are put on the mother's body and she Is IU<ely to experience sickness,
tiredness, lower-back pain, heartbu rn,lncreased appetite and muscle cramps, as well as the
enlargement of her breasts a nd stretch marks. Her blood sugar levels, heart rate and
breathing also increase to cope with the growing demands of the fetus.
As the date of labour approaches, the mother feels sudden contractions known as
Braxton-Hicks, and the neck of her uterus begins to soften and thin out. Meanwhile, the lungs
of the fetus fill with surfactant. This substance enables the lungs to soften, making them able
to inflate when it takes its first breath of air. Finally, chemical signals from the fetus trigger the
uterus to go into labour.

"Many demands ore put on the

mother's body and she is likely to
experience sickness and cramps"

ARST TRIMESTER (0-12 weeks)

This begins after the last menstrual period, when an egg is The fetus grows rapidly and Its organs Hair and teeth
released and fertilised. It takes about nine weeks for the mature. By week zo its movements can At 16 weeks, fine hair
be felt. At week 2.4 it can suck Its thumb (lanugo) grows """"the
resulting embryo to develop Into a fetus. During this period, fetal body. By 20 weeks,
the mother will be prone to sick ness and mood swings due to and hiccup, and can llve Independently teeth start forming in the
hormonal changes. oflhe mother with medical support. jaw and hair grows.

Head Heart Movement

Face begins to AI the internal By week 16 the eyes
look t.Jman and organs are can move and the
the br.lin is fonned and the whole fetus makes
developing 131>idly. heart is able to vigorous movements.
pump blood
around its body.
Sol.l1d and light
The fetus will respond
to light and is able to
hear sounds such as
the mother's voice.

I
I Vernix
I 8y20weeks,
I this white. waxy
I
I substa ""'
I covers the siOO,
I protec:mg it
I from the
I
I ~
I
I
Weight a ••liotic fluid.
I Week 16: l40g
I Week 20: 340g
I Sweating
I An increase in
I Length blood ciraJiation
Weight Length : Week 16: l8cm causes mJtltet to
~ lOg 5.San I Week 20: 25em sweat more.

072
HEAD2 MENONLY 1. Seahorses ED:mt----=-., dragons
2. Komocto 3. Spotted hyenas
HEAD ·~- . The female seahorse
deposits her eggs In the female komodo dragons
Female spotted hyenas have
• genitalia like a penis. It

.,~ ~ '
pouch of the male sealhors:e. can gfve birth to male stretches to aIbN the Insertion
He fertilises the egQS and babies without fertilisation of the male penis during
ANIMAL · .'
1 carr'ies them f()( the full from a male partner. This Is copulation. and sttetches again
PREGNANCIES ~~~ · tetm of three weeks. known as parthe~is. when giving birth through it.

ltU•JU•11J!3N•IW 200 extra calories o doy ore needed in mid-pregnancy, which is 10 per cent more than the usual

Wharton's jelly
place11la The umbilical blood wssels are coated with
this jely~ike substance and protected by a
The placenta is an essential interface between
the mother and fetus. When mature it is a 22cm ~ .
tough yet flexible outer membrane.

diameter, flat oval shape with a2.5cm bulge in

the centre. The three intertwined blood
vessels from the cord radiate from the centre
to the edges of the placenta. Like tree roots,
thesevillousstructures penetrate the
placenta and link to 15 to 20 lobes on
the maternal surface.
The five major functions of the
placenta deal with respiration, •
nutrition, excretion of waste
products, bacterial protection
and the production of hormones.
Placenta body- - - --+
Is firmly attached to the inside
of the mother's uterus.

Maternal su-face ---~r

Blood from the mother is absorbed and
transferred to the fetal surfaoe.

Fetal surface ----------

Blood vessels radiate out from the umbilical
oord and penetrate the placenta. The surface
is covened with the thin amnion membrane.

Umbilical cord -----------

Consists of threeblood wssels. carbon
Two carry

-
dioxide and waste from the fetus, the other supplies
mcygen and nutrients from the mother.
CSctence Photo Library

THIRD TRIMESTER (28-40 weeks)

Now almost at full term, the fetus can recognise and
Breathlessness
The increased size of the
Movement
By the 28th week, respond to sounds and changes in light. Fat begins "The three
fetus by 24weeks
causes compression of
due to less room in
uterus, the fetus wiJ
to be stored under the skin and the lungs are the
very last organs to mature.
intertwined
rib cage and diSC<lfllfort
for mother.
wriggle if it feels
uncomfortable. blood vessels
Week24 Hands
radiate from
The fetus can move
its hands to touch
1 the centre to
its 001bilical cord at
24weeks.
the edges of
the plancenta"
Position
By 28 weeks, the
uterus has risen to a
position between
the nawl and the
breastbone.
Under pressure
'' Pressure on the diaphragm and
'' other organs causes indigestion

'' and heartblrn in the mother. She

will find it diffiCUlt to eat a lot.
''
'
'' Position
Weight Head
Thehead
'''' Head positions itself downwards,
in preparation for labour.
Week 24: 650g I
Week 28: 1,250g can move I Weight
at 28weeks t l ,SOOg
Length and the eyes I
t
Sleep patterns
Week 24 : 34cm can open t Length Fetus wiDsleep and wake in
Week 28: 38cm and see. t 41cm 20-minute cycles.

073
Discover how a fertilised egg transforms into
•
an embryo and eventually a new human being
After fertilisation, the single-celled zygote splits cells, or outer coat, will become, among other thl ngs, the
into two, then the two cells double to four, fourto placenta that nourishes the baby; the Inner cells, known as
eight and so on. The journey along the Fallopian the inner cell mass, wUJ become the foetus Itself. On contact,
tube is quite slow, while growth continues. On its the blastocyst burrows into the uterine wall for nourishment;
way, the zygote divides to mal<e a clump of Jzcells, known as this process is known as implantation. Blastocyst formation
the morulastage. lfthe early embryo splits Into two clumps usually occurs on the fifth day after fertilisation.
before this, it may develop into Identical twins. Every cell In The embryonicstage begins in the fifth week. From weeks
the morula could still become part of the growing embryo. live to eight, development is rapid. Major body organs and
By the time the womb cavity Is reached, the cell cluster systems, including the brain, lungs, liver and stomach, will
becomes hollow and Hlled with fluid; It Is now referred to as begin to emerge. At this time, the first bone cells will also
the blastocyst. A blastocyst is an embryo that has developed to appear. By the end of the eighth week, the embryo Is known
the stage where it has two different cell types: the surface as a foetus and increasingly looks like a mini human.

Fertilisation and IVF explained

Natural fertlllsatlon takes place via sexual wbere It Implants into tbe uterine lining. In vitro
lntercourse.Anegg,orovum, is released by an fertilisation (JVFIIsa form of assisted reproductive
ovary and Is fertilised by a sperm. Fertilisation technology, wbere tbe sperm nucleus Is combined Ovulated egg
occurswben tbe sperm and esg unite In one of the wlthanesgcelllna lab. Tbe resultanternbfYOis ,...., spenn eels...,
female's Fallopian tubes. Tbe fertilised egg, known manually Introduced to tbe uterus, wbere It c:herricaly atb3c:ted to the
as a single-relied zygote, then travels to the uterus, develops In tbe same way as a natural conception. egg and attach thernseM!s
in an attorrc>t to break
Uterus (womb) ~the outer mat.
,...., whole process from ejaculation to
fertiisation can -less than an hour. ~a Ovary - - - - ,
woman has an iM!r'age 28-day menstrual A "'""""" LISualiy has two tubes and
cycle, fertiisation is ocx.nted as having - n two ovaries, one either side of her
place around day 14, not on day one. uterus. Every month one of the
ovaries releases an egg. which
passes slowly along its Falopian
tube towards the womb.

Fallopian tube
Fertilised egg _ __, If a woman has sexual
Only one spenn wil be intercourse during the
successftt,...., egg wit days of her moo ol!lly cycle,
then lose its atlJitdi<Y, just ~ore"' after an egg
harden its outer sl-d and has been relNsed from
t h e - 5j)el'tTI willet the CNatY. a spenn cell
go. If eggs..., not from her partner cooJd
fertiised witm 12 hours lriO\Iel to the Fa~c!>ian tube
ol release, they die. and fertilise the ovum.

In vitro ('k1 glass')

IVf is the pooa55 by -..hch eggs are Spenn
remo....d from the ovaries and milced o..ing sexual~ millions ol spenn are
with sperm in a labooaiOI y culble dish. ejarulated into the vagina. with O<lly ~
fe tiisa6uo I talces place .. INs dish. suviving to make the journey to meet the egg.

074
f.U•JtJ•l!lltW•lfi!ii> In zoog, almost two per cent of oil oobies born in the UK were conceived as o result of IVF

075
 human stomach

Discover how this amazing digestive organ stretches, churns and holds
corrosive acid to break down our food, all without getting damaged
The stomach's major role is as a the rugae flatten, allowing the stomach to cells (G-cells} to make the hormone gastrin,
reservoir lor food; it allows large expand, and the outer muscles relax. The which encourages even more acid production.
meals to be consumed In one sitting stomach can accommodate about a litre (1.8 The stomach empties its contents into the
before being gradually emptied into pints} of food without discomfort. sma ll intestine through the pyloric sphincter.
the small intestine. A combi nation of acid, The expansion of the stomach activates Liqu ids pass through the sphincter easily, but
protein-digesting enzymes a nd vigorous stretch receptors, which trigger nerve solids must be s maller than one to two
churning action breaks the s tomach conte nts signalling that results in increased acid mi ll! metres (0.04·0.o8 inches} in diameter
down into an easier-to-process liquid form, production and powerful muscle contractions before they wi ll fit. Anything larger is 'refluxed'
preparing food lor absorption in the bowels. to mix and churn the contents. Gastric acid backwards into the rna in chamber for further
In its resting s tate, the stomach is contracted causes proteins in the food to unravel, allowing churning and enzymatic breakdown. lttakes
and the internal surface of the organ folds into access by the enzyme pepsin, which breaks about two hours for half a meal to pass into the
characteristic ridges, or rugae. When we start down protein. The presence of partially small intestine and the process is generally
eating, however, the stomach begins to distend; digested proteins stimulates enteroendocrine complete within lour to five hours.

Lining under the microscope

The stomach is much more than just a storage bag. Chief cell (yellow)
Qjef eels mal<e pepsmgen; at the low pH
Take a look at its complex microanatomy now...
"'the stomach it becooleS the digestille
enzyme~ wnchdea:>nsiJUc:ts .. .,....
_ ..... ..
Gastric pits - - - - - - - - ---. . - - - - - - - - - - - - - Mucous cell
The entre ...-face of the Thesecellsseaete-.e
stomach is~"' my rrucus to protect the
holes, wiW::h lead to the stomach fining from damage
glands that prodJoe nu:us. by stolo oach acid.
acid and enzymes.

Mucosa

- - - - - - - - G-cell (pink)
Also known as
enteroendocrine cells,
these produce hormones
li<e gastrin, which regulate
acid production and
stomach contraction.

Submucosa - {

Muscle layers
The stomach has three layers
These cells prodJoe hldoc:hloric ol rn..oscle llnling "' o:ifferent
acid. .....nich kils off onicro- orientalioos. These produce
organisms.I-IY<M!Is protei'os and the C<Hlrdmted contraction
activates digestive enzymes. requi'ed to mix food.

076
I•U•JW•1!113N•IW Stomach rumbling, also known as borborygmus, is actually the noise of air movement 1n the intestines

~-------- Fundus
Gastric anatomy The top portico I of the
stomach Q.I'Ve5 upa:ld
This major organ in the digestive system has several distinct alows gases created
regions with different functions, as we highlight here dfilg tigestiol I to
be collected.

Cardia - - - - - - -
The oesophagus empties into
the stomach at the cardia. This
region makes lots of mucus,
but ittle acid or enzymes.
Pyloric sphincter
The pyloric sphinot..- is a strong
nng of muscle that regulates the
passage of food from the Ant rum - - - ----.,
stomach to the bowels. The antnm cootains cells that
can stim uJate or shut off acid
prodJction, regulating the pH
level of the stomach.

' - - - - - - - Body
Also called the corpus, this
is the largest part of the
stomach and is respoosi:>le
for stomg food as gastric
juices are i1trodJced.

Small intest ine -...J

The stomach empties into
the fi'S! section of the smaU Pancreas
intestine: the duodenum. The bottom of the stomach ~- Large intestine
Is located In front of the The large intestine curts
pancreas, although the two around and rests just below
aren't directly connected. the stomach in the abdomen.

Why doesn't it Produced by parietal Vomit reflex

digest itself?
cells in the stomach
lining, gastric acid has a
step-by-step
pH level of L5 to Vomiting is the forceful expulsion
Your stomach i.s full of corrosive acid and of the stomach contents up the
enzymes capable of breaking down protein - if oesophagus and out of the mouth.
left unprotected the stomach lining would It's the result of three co-ordinated
quickly be destroyed. To prevent this from stages. First, a deep breath is
occurring, the cells linlng the stomach wall drawn and the body closes the
produce carbohydrate-rich mucus, which form.s glottis, covering the entrance to
a slippery, gel-like barrier. The mucus contains the lung.s. The diaphragm then
bicarbonate, which is alkaline and buffers the pH contracts, lowering pressure in the
at the surface of the stomach lining, preventing thorax to open up the oesophagus.
damage by acid. For added protection, the At the same time, the muscles of
protein-digesting enzyme pepsin is created from the abdominal wall contract,
a zymogen (the enzyme in its inactive form)- which squeezes the stomach. The
pepsinogen; it only becomes active when it combined shifts in pressure both
comes into contact with acid, a safe distance inside and outside the stomach
away from the cells that manufacture it. forces any contents upwards.

077
 ur heart

1. The blocked artery _.....,;._ _,

Angioplasty is a cutting-edge Fatty plaques can block any of

the four main arteries that fe«<
the heart. leading to pain.
meaical procedure that helps
your heart last longer 2 Access _ _ _ _ _ _ _ _~...-.-;.._______,
Your heart pumps blood-rich oxygen Guidewires are fed irto these arteries via the small
to your body's tissues- but the heart arteries in the groin or wrist. Even ~ the patient is
;make. they don't feel it as a local anaestlletic is 9ven,
muscle needs oxygen Itself. The
coronary arteries are small vessels )
S. Up dose
lining your heart's surface that do this job Hi!jl blood pres.sue leads to~ spots of damage on artery
perfectly, in exactsynchronlsallon with the beats wals. These w* fill with cells, inc:luOOg fatty lipid eels. It is
of the heart. However, they can become blocked. A the COO'tlinationsof al of these cells that lead to a fbosis.
lack of exercise, smoking. poordletand unlucky stiff plaqo oe that narrows and then blocks the artery.
genes can all lead to plaques of fatty tissue. called
atheroma, blockingthesevitalanertes. Then, If
your heart needs to pump harder. such as during
exercise, the reduced blood Row can not supply
enough oxygen. This leads to pain -angina -
which is an early warning sign that the heart
muscle is dying. Previously, the only way to cure
advanced cases was to go under the surgeon's
knife. However, cardiac surgery Is a risky
procedure. Then along came angloplasty.
Via a small artery in the patient's groin or wrist,
doctors Insert a guide wire directly Into the
coronaryarteries of the heart. This Is tricky, and
so they use rea l-time X-ray images to guide them
to exactly the right place.They feed a tiny. thin,
flexible hollow tube over this wire (a catheter).
Injecting dye into these arteries (via the hollow
catheters) and looking carefully at the resu It
shows them exactly where the blockages are.
Next, they inflate tiny balloons attached to the end
of these long catheters at the exact spot of the
blockage.lnsome cases, this Is enough.ln others,
to prevent thearterydoslngagaln,a stentcan be
placed through the affected area. These are clever
The
Angioplasty is one of the most commonly
stentsand can contain drugs that prevent them
blocking. A6nal check X-ray completes the performed medical procedures around
angioplasty process. the world - there's a good chance that you
Angioplasties like this can also be performed know someone who's had one. However,
on blocked arteries In the legs, where the the procedure still requires a lot of
principle is exactly the same. But no matter technical skill and a steady hand. Even in
where the blockage is, this procedure requires a
steady hand and a doctor who can think fast and the best hands there are risks and
think in real-timeJOwhlle looklngat2D complications, but most people get good
black-and-white Images. results from it
078
 •
•
•• •• ••
•
•• No napping
• •
•• All the way up? ••
Drug eluting High tech all the way •• Lasers
1 The most modem stents that
are used in angioplasty
•
!
:
2 ln the modem era,
angioplasty patients stay
3 Once the ballooring and
stenting is done. the tech
••
•
• 4 Although an angbplastyis
mainly usedonooronary
:5
:
Recent angioplasty·
related te<::Mological
•
procedures aren't just bare •• awake during the entire doesn't stop. There are devices
•••
arteries, there are some •
•
developments inclJde using
metal somealsosecretedrugs • procedure, as it is now to close holes made in the groin doctors trialing angioplasty for • lasers at the eod of the
over time, which work to •• performed with the patient or wrist arteries to stop them •• narrowed arteries that feed •• catheters to bum away the
prevent a blockage. • under local anaesthetic. • blood to the brain • offending plaques.
• getting bigger.
• •

ltU•JU•11J!3N•IW Emergency ongiop/osty is the best treatment for acute heart attacks

3. X-rays
Under real·time X·ray
image guidance, the
guidewires and catheters
are fed through the maja-
arteries and then into the
tiny coronary arteries.

lr~'-'-;;---=--;;;;;~~---~ 4. The blockage

Using dyes, the X·rays show
the doctors where the exact
blockages are, and then the
catheters are introduced
t hrough these narrowings.

6. Widening the gap

The stent is placed through the
blockage, and then expanded From a
within it. This is all done under
X·ray guidance so it's in exactly
the right positio n. horsetotM
whole
The first a ngioplasty of the heart was carried out
7. The stent in the 18th Century on a horse. It took a while to
Onoe the stent is fully perfect !tfor humans, and in 1929 the first
expanded, the catheter holding angioplasty on a person's heart was performed
it is removed, leaving it in place
to prevent reblockage.
in Germany. Over the next3oyearsa small
number of doctors pioneered the angioplasty
into a diagnostic and therapeutic technique.
While in the Sixties and Seventies open heart
r-- - - 8. Increased flow surgery became established, in the Seventies
Naw the artery is wider, more and Eighties angioplasty started to take over as a
blood flows. delivering vital lower risk but equally effective treatment.
oxygen to the heart muscle and Astonishingly, In the late-Nineties, over 1million
preventing the pain of angina. angioplasties were performed worldwide,
making it one of the most common medical
procedures on the planet.

catheter
The balloon catheter is one of the key pieces of the angioplasty
doctor's equipment. Once the guidewire is inserted, the catheter is
fed over it and floated into exactly the right place. Through this
catheter, special dyes that can be seen onX-rayimages(radio-opaque
contrast dye) can be injected through the hollow catheter to confirm
its position and then confirm the location of the blockages.
At the tip of the catheter is a balloon. Using water, this balloon can
be inflated from outside to precise pressures. When this is done from
the centre of the blockage, the atheromatous plaque is expanded to
allow more blood flow. There are many different sizes of catheter and
widths of balloons, allowing exact tailoring to the patient's needs.
Sometimes the doctor will start with a small balloon when the
blockage is very narrow, and then sequentially insert larger balloons
to allow for the maximum effect. However, care is needed - too large a
balloon or too much pressure and the vessel can rupture, which is a
life-threatening complication. Experience, care and control of the
pressures prevent this.

079
 ow do our hands work?

The human hand Is an Important

feature of the human body,
which allows Individuals to
manipulatetheirsurroundlngs
and also to gather large amounts of data from
n
the environment that the lndivldualls
situated within. Ahand Is generally defined We take our hands for granted, but they are
as thetermillal aspect of the human arm,
which consists of prehensile digits, an actually quite complex and have been
opposable thumb, and a wrist and palm.
Although many other animals have similar crucial in our evolution
structures, only primates and a limited
number of other vertebrates can be said to
have a 'hand' due to the need for an
• Distal phalanges - - - - t -
opposable thumb to be present and the A disU!I phalange (fingertip) is situated
degree of extra articulation that the human
hand can achieve. Due to this extra
articulation, humans have developed fine
the hand
The human handcontalns27
at the end of each finger. Deep flexors
attach to this booe to allow for
maximt.m movement

motor skills allowing for much Increased bones, and these divide up Into Intermediate --------...
control in this limb. Consequently we see three dlstlnctgroups: the phalanges
improved ability to grasp and grip Items and carpals, metacarpals and This is where the
development or skills such as wrlll ng. phalanges. These also then superfiCial fte><>rs attach
Anormal human hand Is made up of five further break down into three: via tendons to alow the
digits, the palm and wrist. It consists of 27 the proximal phalanges, digit to bend.
bones, tendons, muscles and nerves, with Intermediate phalanges and
each fingertip of each digit containing distal phalanges. Eight bones Proximal ------i:-11-""~
numerous nerve endlngsmaklng the hand a are situated In the wrist and phalanges
Each fuger has tine
crucial area forgathering iniormatlon from these are collectively called phal;vlges, and INs phalange
the environment usingoneof man's most the carpals. The metacarpals, ;oos the nl!r1llledate to its
crucial five senses: touch. Muscles Interact which are situated in the palm respediye~
together with tendons to allow fingers to of the hand account for a
bend, straighten, point and, ln the case oft he further five out of the 27, and ~~~ ------~~~~~
thumb, rotate. However, the hand Is an area each finger has three These""" bones make~ l!le
thatseesmanyinjurlesdue to the number of phalanges, the thumb has two. P<*n and each one ai!;J1s
ways we use it. one in ten Injuries In A&E lntrinslcmusclesandtendons with one ol the hand's digits.
being hand related, and there are also Interact to control movement of
several disorders that can affect the hand thedigltsandhand, andattach
development In the womb, such as to extrinsic muscles that ~~ ----------~--~
polydactyly, where an lndivldualls born Thecarpals(SC<~Phoid, ~·· ~.
extend further up into the arm, trapezoid. k.nrte. hamate. capitate and
with extra digits, which are often In perfect which flex the digits. pisiform) sit between the !Ana and radius
working order. and the metacarpals.

080
 1. Julio Cesar 2. Gianluigi 3. lker Casillas
Soares de Buffon Fernandez
Espindola Named the 'Se.-le A Voted best goalie in the
Having r'ecovered From a Goalkeepe,; of the Year' a wor1d by the lnten'lational
few eaflier' blunder'S, the rec:Of'd nine times, this is Federation of Foo!OOII
Brazilian keel)e( is now one guy It would be hard HistOtY and Statistics for
considered one of the best. to put one past two years running.

ltU•JU•11J!3N•IW Skin is attached to tendons and so when you bend you fingers bock, dimples appear on the bock of your hand

Muscles and other structures

The movements and articulations of the hand and complex mix of tendons and intrinsic muscles to
by the digits are controlled by tendons and two operate (extensors). These muscles will contract in
muscle groups situated within the hand and wrist. order to cause digit movement and Oexorsand
These are the extrinsic and intrinsic muscle groups, extensors work in a pair to complement each to
so named as the extrinsics are attached to muscles straighten and bend digits. The intrinsic muscles
which extend into the forearm, whereas the are responsible for aiding extrinsic muscle action
intrinsics are situated within the hand and wrist. and other movements in the digits and have three
The flexors and extensors, which make up the distinct groups; the thenar and hypothenar
extrinsic muscles, use either exclusively tendons to (referring to the thumb and little linger
attach to digits they control (flexors) or a more respectively), the interossei and the lumbrical.

Thenar space --""""

Thenar refers to the thumb,
and this spaoe is situated
between the first digit and
thumb. One of the deep
flexors (extrinsic ITKJSCie) is
located in here.

Interossei
muscle
(intrinsic) - - - - - -
This interossei musde sits
between metacarpal
bones and will unite w ith
tendons to allow extension Ulnar nerve
using extrinsic muscles. This nOM! stretches
down the forearm into
the hand and allows for
sensory information
to be passed from
Arteries, veins hand to brain.
and nerves --~
These supply fresh
HYPothenar
oxygenated blood (and musde (intrinsic)
take away deoxygenated Hypothenar refers to the little
blood) to hand muscles. finger and this musde group is one
of the intrinsic ITKJSCies.

Insertion of flexor tendon ....____ Mid palmar space

This is where the tendon attaches the Tendons and intrinsic muscles
flexor muscle to the finger bones to primarily inhabit this spaoe
Extrinsic muscles are so allow artirulation. within the hand.
called because they are
primarily situated outside
the hand, the body of the
muscles situated along the
underside or front of the
forearm. This body of
muscles actually breaks
down into two quite distinct
groups: the Oexors and the
extensors. The Oexors run
alongside the underside of
the armand allow for the
bending of the digits,
whereas the extensor
intrinsicsand ..:::::::=;~~~~~~
muscles' main purpose Is the
reverse this action, to
Tendons
These attach the
straighten the digits. There
flexor muscles to the
are both deep and superficial phalanges, and facilitate ~----- Extensors
Oexors and extensors, and bending. Tendons also Thenars Superficial flexors Deep f lexors Exter=rs on the back of
whichareusedatanyone interact \Yith the intrinsics The intrinsic group of The other flexor that acts on The digits halie two extrinsic flexcxs that the foreann st raighten the
time depends on the digit to and extensors in the wrist, m uscles is used to flex the the digits is the superior flexor, allow the.-n to bend, the deep flexor and cfigits. Divided into six
be moved. palm and forearm to thumb and control its which attaches to the the superficial The deep flexor attaches sections. their connection
straighten the digits. sideways rllO'w'em ent. intennediate phalanges. to the distal phalanges. to the digits is complex.

081
 ee- jerk reactions 1 Fingernails
-
3. Interneuron
The knee-jerk step-by-step The intErneum J)fOVWies a
comectian between the
L Quadriceps and hamstring muscles sensory a1d motor netrOflS.
The knee jerl< reflex means that the q.Jadriceps ....-s
mnlract at the sane trne the harnsbWlg muscle rela-.

IOns
•
I
Why does your leg kick out
when the doctor taps just
below your knee?
Doctors often test the knee-jerk, or patellar
reflex, to look for potential neurological
4. Motor neuron
problems. Lightly tapping your patellar tendon The motor, or efferent
just below the kneecap stretches the femora l neuron, carries the nerve
nerve located In your thigh, which In turn causes your impulse to the muscles.
thigh muscle (quadriceps) to contract and the lower leg to
extend. When struck, impulsestravelalonga pathway In ' - - - 5. Spinal cord
the dorsal root ganglion, a bundle of nerves In the 41evel 2. Sensory neuron _..J The spinal cord has both gey
• Sensory neuron The sensory, or affetent matter, whid:l conta01s nerve eel
of the spinal cord. ReO ex actions are performed • Motor neuron neu-on. ~an impulse bodies, a1d while matter, whid:l
independently of the brain. This allows them to happen Interneuron
contains the """"' fbres.
from the femcral """"'·
almost instantaneously-lnabout 50 milliseconds In the
case of the knee-jerk reOex. This reOex helps you to
maintain balance and posture when you walk, without
"Reflex actions ore performed
having to think about every step you take. independently of tfie brain"

are r
fi ils
maCie
And how are they formed?
fingernails are made of a tough protein called keratin (from the
Greek word 'Kera', meaning horn). Keratin Is also what animals
hooves and horns are made from. Most animals have a supportive
bone structure In their horns, although rhinoceros horns are made
completely of keratl n compacted together. The only other biological material
which has a similar toughness to kerall nlsed tissue is chitin, the main
component of exoskeletons belonging to arthropods. The half-moon shape
thatyoucanseeat the bottom ofyournail (apart from maybe your little linger)
is called the lanula. Thlsls agroupofcells that produce keratinandother living
cells. As these livlngceUs arepushed forward by newer cells, they die and
merge with the keratin to become kerltlnlsed. They then become Oauened,
stiff and known as your fingernails.

"The half- moon shape that you

con see at the bottom of your nail
is called the lonulo"
082
 the leg at the knee.

...
.. .. .

•
 •
Feet are immensely complex structures,
y:et we put huge amounts of pressure on
them every day. How do they cope?
. -
·&"
The human footandankle Is crucial for locomotion
• • • and Is one of the most complex structures of the
human body. Thls Intricate structure Is made
T~ ------------------~
Te<minal aspects of the foot
that aid balance by grasping
J
up of no less than 26 bones. 20 muscles, 33 onto the ground. They are the
equivalent of fingers in the
joints -although only 20 are articulated-as well as numerous
foot structure.
tendons and ligaments. Tendons connect the muscles to the
bones and facllitate movement of the foot, while ligaments hold
the tendons in place and help the foot move up and down to Muscles - including the extensor
digiton..m brevis m.Jscle _ _...../
inltiatewalking.Arches In the foot are formed by ligaments,
Muscles within the foot~ the foot lift and
muscles and foot bones and help to distribute weight. as well as articulab> as necessary. The extensor dgitonm
making it easier for the foot to operate efficiently when walking brevis rruscle sits on the top of the foot, and
andnmning.lt Is due to the unlquestructureof the foot and the helps flex cijts tw<Hot.- on the foot.
way it distributes pressure throughout all aspects that it can
withstand constant pressure throughout the day. Blood vessels _ _ _....../
One of the other crudal functions of the foot Is to aid balance, These supply blood to the foot,
and toesareacruclalaspect of this. The big toe In particular f<ditati 19 rruscle upeatitw oby
helps in this area. as we can grip the ground with It Ifwe feel we ~energy and oxygen and

are losing balance. rer"llOIIWlg deoxygenated blood.

The skin, nerves and blood vessels make up the rest of the
foot. helping to hold the shape and also supplying It with all the ~~ ------~
necessary minerals, oxygen and energy to help keep It moving Ligaments support the
tendons and help to form the
~ ....__
easily and constantly.
arclles of the foot, spreadO>g
weight aaoss it.

What happens when Tendons (extensor digitorum

you spra1n your ankle? longus, among others) ----------~~+
Fibrous bands of tissue which corvJeCt
muscles to bones. They can w ithstand a lot
A sprained ankle Is the most common type of soft tissue
of tension and IJnk various aspects of the
Injury. The severltyof the spraIn can depend on how you foot, facilitating """""""nt
sprained the ankle, and a minor sprain will generally
consist ofa stretched or only partially torn ligament
However, more severe sprains can cause the ligament Tibia - - - - - - - " " '
The larger and stronger of the lower
to tear completely, or even force a piece of bone to leg bones, this ~M5 the knee and the
breakoff. ankle bones of the foot
Generally a sprain happens
when you lose balance or slip, Fibula
and the foot bends Inwards This bone sits alongside the Iilia, also
towards the other leg. ThIs then ~thekneeandthe~. --------~
overstretches the ligaments
and causes the damage. Over
a quarter of all sporting
injuries are sprains
The...._
of the ankle.
ofthefoot
andhowthe
work
084
 •
•
•• •• ••
• • • ••
• • •
Bunions •• Athlete's foot •• Warts • Ingrown toenails •• Achilles tendonitis
STOP 1 This is an enlargement of the skin
or tissue around the big toe.
••
•
2 A fmgal infection that's often
tra'lsmitted in areas where
•
•• 3
Warts are smaH, benign
lumps of skin. which appear
•
•
•• 4
Ingrown toenaisare a form ol
nail disease where the nail
•
•• 5 This is the inRammation
of the Achilles tendon.

FACTS Formation is often attributed to

ill.fitting shoes. thou~ it's
suspected that genetics is the
•••

•
•
••
people walk around barefoot,
this develops when t he skin is
not properly dried and aired. It
•
•••
••
•
following exposure to a
virus ... most commonly
the human papillomavirus
•
•
••
••
•
grows into either side of the
nail bed. Infection can often
occur if il is not caught and
•••
•
••
•
wl'jch occurs prior to the
ruptl.re of the tendon.
and is commoriy seen
FOOT AILMENTS -problem. • displays as flaky. itchy skin. • 2and7. • treated early. • in athletes.

ltU•JU•11J!3N•IW In a lifetime, a person will walk the equivalent of four times around the globe - more than 1oo,ooo miles!

4. Leg swing _ !
The lower leg wiD
then swing at the
knee, l.Wlder the body,
'Human gait' is the term to describe how we to be placed in front
walk. This gait will vary between each of the stationary,
person, but the basics are the same weight· bearing foot.

2. Weight transfer ---...

The weight wiD transfer fuRy
to the foot still in contact
with the ground, normally
with a slight leaning
movement of the body.
6. Repeat
process
3. Foot lift - --/ S.Heel - - ' 1. Heel lift - - - - - J The process is
After weight has placement The first step of walking is for then repeated with
transferred and the The heel will normally be the foot to be lifted off the the other foot. During
individual feels the part of the foot that's ground The knee wil raise and nonnal walking or
balanoed, the ball of placed f.-st. and weight the calf muscle and Achilles running. one foot will
the first foot will then wiB start to transfer back tendon, situated oo the back of start to lift as the other
lift off the gound, onto this foot as ~ hits the leg, wiD contract to allow starts to CClflle into
raising the thigh. the ground. the heel to lift off the ground. contact with the ground.

Distal Proximal Metatarsals Cuneifonns Navicular

phalanges phalanges The five, long bones that are bones (three) This booe, which is
The booes which These booes link the the metatarsals are located Three booes that fuse so named due
sa at the far end metatarsals and the between the tarsal booes together during booe to its resemblance
of the foot and distal phalanges and and the phalanges. These development and sit to a boat, articulates
make up the tips stretch from the are the eqlivalent of the between the metatarsals with the t hree Ababylsbomwlth22.
of the toes. base of the toes. metacarpals in the hand and the talus. cuneiform booes. out of a tota!2.6 bones in each foot

6
0

3"
i

- ,•
•
. ~

·-

' - - - Cuboid Calcaneus

One of five irregular bones The talus is the This bone
(cuboid, navicular and three secood largest constitutes the
cooeiform booes) which make booe of the foot, heel and is crucial
up the arches of the foot and it makes up for walking. It is
These help with shock the lower part of the largest bone
absorption in locomotion. the ankle joint. in the foot.

085
 Achilles' tendon 1 Smelly feet

~I?
Producing up to a
Qintofsweateach
aay, no wonder xour
feet get a bit whtffy Facts: Well known for tl>eir ability
to secr~te a liQuid with a strong.
Sweat actually keeps the foul smelhng oclcu which they
CM use as a defensive weapon.
sldn of our feet moist and They can shoot it up to 5 metres.
flexible to cope with the
constantly changing
pressure when we walk. Without
this moisture the skin would dry and
crack, and walking would become
extremely painful.
Despite the huge number of glands
(Z5o,ooo per foot) and amount of
2. Rotorua, New
sweat that comes from our feet, Zealand
remember It's still just salt and water. Facts: located in the most
Tt'"n dmu o.f The odour comes from the bacteria geclogio:aly active area of New
Zealand,Racruaissuroun:led
Pf:701HU. Um!JI.U that live on human skin which, while by mud pools. geysers ard
rl brn:~ unsettling. are perfectly naturaI. Our $team vents.
socks are a dark, moist-Infested feast
for them, as they eat sweat and dead
skin. It Is the waste products they
excrete from thls consumption that
are what smells bad. The more the
bacteria eat the worse our feet smell.
To keep the smell down, make sure
you changeyoursocksand let your 3. Titan arum
shoes alr for 24 hours If you can. Also, facts: This monsttOus. ttwe-
metre tal plant smells li~ a
wash your feet and spray them with combination of rotten eggs and
antiperspirant! ronlng meat to attract insects.

The wonderful smell of

freshly cut grass, daisies
and feet...

Is it really a weal< spot and how

important is it?
Tbis tendon, the strongest In your body, connects the calf muscles to
the heel. When everything Is Hne, It pulls the back of the foot up
when the call muscles contract. This way, your heel raises and your
weight goes to your toes. It enables us to do such things as sprinting.
bopping or jumping. It also stores elastic energy to do these tasks more
efficiently. Biological anthropologists believe all this was very important for the
way we evolved to run around on two legs and survive.
The Achilles' tendon Is seemingly named thus after the mythological Greek
character of Achilles, who during th.e Trojan War- made famous by Homers epic
poem The Jlliad -Is shot by a poisoned arrow In his unprotected heel -hence the
common phrase describing a person's weak point.

086
I•U•Itm!Jt:W•l!illi> writers' cramp occurs in the hands and lower arms but is actually a form of dystonia. a neurological condition

Why do our muscles tense up?

Cramp Is an Involuntary contraction of a muscle, often in
a limb such as the leg, that can cause pain and discomfort
for seconds, minutes or, in extreme cases, for several
hours. They are most common after or during exerctse,

are coinciding with low blood sugar levels, dehydration and a high loss of
sa It from sweating. Although the full range of causes is something of a
mystery due to limited research in the area, cramp Is believed to be
Why do burns cause bubbles to develop the result of muscle fatigue. If a muscle has been shortened through
prolonged use but Is repeatedly stimulated, It isn't able to properly
below the surface of the skin? relax. Areflex arc from the central nervous system to the muscle
informs It to continue contracting when It Is not necessary, leading to
Though our skin Is an and Hils the spaces between the layers
~~ amazing protector against of skin in order to cushion the
a painful spasm knownascrampas the muscle continually attempts
to contract. This Is why athletes pushed beyond their limits, such as
Jil ' the elements, it can become
damaged by such factors as
underlying skin that is being rubbed
and protect it from further damage. As
football players who have to play extra lime In a soccer match, and
long-distance runners. will often experience this condition..
beat, cold, friction, chemicals, light. moreandmoreserumpoursintothe
electridty and radiation, all of which space, the skin begins to inflate under
'burn' the skin.A blister Is the resulting the pressure, forming a small balloon
injury that develops in the upper layers full of the serous liquid. Given time to
oftheskinasa result of such burns. heal, the skin will reabsorb the plasma Rest
The most common example of a after about 24 hours. N. rest the calf
trU5de is in its
blister, which we've no doubt all Similarly, a blood blister is a variation
experienced at some time, Is due to the of the same injury where the skin bas
relailltd poWon.
I
repeated friction caused by the material been forcefully pinched or crushed but Stretch
of a pair of shoes rubbingagalnst. and not pierced, causing small blood vessels When the leg is
bin orstretdied
irritating. the skin. The resulting water ro rupture, leaking blood into the skin.
the calf rTUicle
blister is a kind of plasma·filled bubble All blisters can be tender but should wi1 ""' ill a;t, and
that appears just below the top layers or never be popped in order to drain the then relax......,
your skin. The plasma, or serum- which fluid as this leaves the underlying skin it is not.
is a component of your blood -Is unprotected and also invites infection
released by the damaged tissue cells Into the open wound.

Blister caused by r------- Plasma

Serum is released by the damaged
second-degree bums tissues into the upper skin '-rs to
prc~~ent further damage below in the
epidermal'-<· It also aids the
healing process, which is why you
should avoid pojll)ing your blisters.

Dlration , . - - - - - Cramp
Skin - . / Ant generated Prolonged
When arry type of tun is Cfilll1l usualy lasts dstJ~etd
..........~l!l of the
experienced. the C>llertying slcin fur a few seconds. leg jll'ell'l!l1ts the
expands as it receives the protec:tille I.--some call rTUicle from
plasma/serwn
...taxing. which can
lasthours. - - - - lead to 00111 rp.

Damage -------~
Tlis pa-tjcUar exa '"*of a blister tun
has caused damage to the loeratii iC)Cytes
in the sl<in. Second-degree bums are Ruid reabsorbed
most often caused ..t.en the slcin comes I'Jter a day <X so the senm wil be
into""' •tact with a hot surface, S<.dl as absabed back into the body and the
an iron <X boil01g water, <X even after raised skin '-rs wil dry out and ftal<e
OXposlR to e>o:essive ..night off in their own time.

087
 •

• I133
exp
uac:zered
104
Why do we
sweat?

110
How ow
bones heal

"
0
g

090 Food and !our body 106 The immune system 124 How yow blood works
Inside the igestive system Combating viruses The miraculous fluid analysed
098 The blood-brain barrier 110 Healin~bone fractwes us Hormones
What important role does it play? How bro en bones are mended The human endocrine system
099 Pituit:f; gland up dose 111 Making lf:otein 110 The u,rinary system
The 'mas er galnd' explored How are ey manufactured? How do we pass waste?
100 Brain electrid~ SY.Dasses 1U Thecell~cle 1)2 Tracheotomysur~ery
Revealing the tru behin both Inside a vi al process A life-saving proce ure
101 Adrenaline 114 White blood cells 1)1 Hayfevel'
How does it effect the body? How infection is fought Why do people suffer?
102 Human respiration u6 The science of genetics 1)4 Exploring the sensory system
The lungs explained How genes defirie who we are How we experience the world
10ft Dehydration I Sweat::tf 121 Burns 11..1 Chickenpox
Why we sweat and using uids The causes and effects of burns How harfuful can it really be?
105 Cinadian rh~ 12.2 Blood vessels 1)9 Why do we cry?
Our body doc explored Our drculations system The different types of tears

088
 n6
DNA
explored

128
The role of
hormones
I

I
112
The cell cycle

"The cell damage

from viruses
causes diseases"
089
 Join us as we unravel all nine
metres of your digestive system
The digestive tract is a long, muscular tube that
runs the entire length of your body. It is separated
into five distinct sections, each with its own
particular and specialised function.
Digestion begins in the mouth. As you chew your food,
saliva is released, providing a slippery lubricant and
kick-starting the break down of carbohydrates with an
enzyme known as amylase. Touch receptors in you r
mouth tell you when it is time to swallow, and as your
tongue comes upward, the food is pushed to the back
of your throat.
As you swallow, you pass control of digestion
over to your automatic motor functions. A flap of
skin called the epiglottis folds down to cover the
voice box, a nd the entrance to the lungs, and
then a wave pushes the mouthful all the way
down the oesophagus. When the food reaches
your stomach, it passes through a ring of muscle
!mown as the cardiac sphincter, which prevents
it from coming back out the way it came in.
The inside of the stomach is a hostile
environment, where the cells lining the walls
pump out hydrochloric acid and protein-digesting
enzymes. The presence of food triggers stretch
receptors in the stomach lining, which in turn trigger a series
of rhytb mic contractions. These churn the stomach contents,
mixing in the acid and enzymes, grinding down the food.
At the bottom of the stomach th ere is a second ring of muscle
called the pyloric sphincter, which acts as a gatekeeper to the
small intestine. The sphincter prevents anything larger than
about two centimetres (o.8 in ches) in diameter passing
through, returning it to the body of the stomach until it has

090
 Shellfish Milk Peanuts
Shellfish allergies tend to Children '-"der the ago or By far the most
dellelop during three are the most likely cOO'Imoo food
adulthood. Foods to ai/Oid to develop an allergy to allergy is peanuts. l.n
Include bamack>s. crabs, milk, but they usually the UK, as many as
shrimps. lobsters, outgrow It by the time one in SO children
crawfish and krill they reaeh adulthood. ate sensitive.

I.U•Ill!I!It:W•I@ Bio/ogica/ wash1ng powder uses digestive enzymes to break down the stains on dirty laundry

been ground down further. This ensures that by

the time it reaches the small intestine, yourfood
Journey of
is a runny, slightly lumpy paste, and is ready for your fOod - - Swallow
Saliva makes each mouthful
the next stage of digestion. It can t ake up to 48 slippe.y, allowing it to slide
The small intestine is the site of chemical hours for a meal to travel easily down the oesophagus
through your body to the stomach.
digestion. He.re, the pancreas adds digestive
enzymes, and the liver adds a generous squirt of Add acid and enzymes
alkaline bile, delivered via the gall bladder. This The stomach produces
bile not only neutralises the burning stomach Chew hydrochloric acid, and
Digestion begins in the protein-digesting enzymes.
acid, it also acts a little like washing-up liquid on
mouth, where our teeth start
dirty dinner dishes, helping to separate the work on grinding food Into . - - Add more enzymes
food particles and forcing fats to disperse into manageable chunks. The pancreas produces
digestive enzymes, which
tiny bubbles. are added to the mixture as
Muscles in the sma II intestine continue to Add bile it enters the small intestine.
As the liquid passes into the
squeeze and mix the contents together, allowing intestines, stomach acid
the enzymes to get to work i nslde the paste. As is neutrali.sed by
the nutrients are released, they are then alkaline bile from
the liver.
absorbed over the wa lls of the Intestine and into
the bloodstream.
To ensure that everything keeps moving
through the system, every five to ten minutes a
wave of muscle contractions begins at the
stomach and travels all the way down the
intestines. Known as them !grating motor naba
complex (MMC), this wave squeezes the digestive LEII&IHCF'IIIE
SIF" III&IZE
system like a tube oftoothpaste, urging its Ferment waste
contents further toward the colon. Bacte<ia filling in the
As the food progresses through the small large intestine help

intestine, more and more of the nutrients are

with the breakdown of Chum
waste, releasing even The muscles of the
released by enzyme activity, and by the time it more nutrients. stomach rhythmically
gets to the large intestine, most of the useful chum its contents,
Absorb nutrients mechanically
material has been absorbed into the breaking food down
As the enzymes begin to
bloodstream. However, the digestive process is release nutrients, they are into a lumpy paste.
not over, and here, bacteria help to break down absorbed across the lining
even more of the undigested food. of the small intestine into
the bloodstream.
The large intestine also absorbs most of the
remaining water, leaving behind a combination
Get rid of waste
of und igested materia l, dead cells and bacteria. All that is left at the
When the waste has completed its journey end of the digestive Remove water
through the large intestine it goes to the rectum process is a The large Intestine
combination of absorbs excess water
for storage until there is a convenient time to get indigestible mate.ial, from the food as it
rid of it. dead cells and bacteria. passes through.

>I I :..

• 0

.' •

•
• ••
.. -- .
• •

091
 =··
Toste and digestion

Sense
Circumvallate papillae
Anatomy of a These large bumps are found at the
bad< of the tongue, each surrounded

human tongue by a dip that collects saliva.

of taste
Taste tells us whether our food is
Co ntrary to popular belief, all five
tastes can be detected almost
anywhere on the tongue
Blood supply
The tongue receives
blood from the lingual
safe to eat, but smell gives it flavour artery and it drains out
through the lingual veins.
Muscle
The human tongue is able to detect five different There are eight
muscles in the
tastes: sweet, sour, salty, bitter and umami tongue that alter
Nerves
The front and back
(savoury), providing us with a quick way to its shape and
of the tongue send
distinguish between different types of food. change its position.
taste information to
Sweet foods contain sugar and are a good sou rce the brain.
of energy. Salty foods provide sod ium, which is
Posterior
vital for nerve function, but deadly in high tongue
quantities. Bitter foods might contain poison. About a third of the
Babies are born with a natural preference for tongue is hidden
right at the back of
sweet food and a dislike of bitter, providing a the mouth.
biological safeguard that encourages them to eat
safe, high-calorie food. However, nutrition is not Foliate
Papillae papillae
that simple. Many vegetables are bitter but not The tongue is
These contain
covered in tiny
poisonous and so learning to like them comes taste receptors
bumps, but not all
with experience. and are located on
of them contain
the back edges of
The degree to which we can detect different taste buds.
the tongue, where
tastes varies, and appears to be dictated by our saliva drips down
individual anatomy. The population can be the cheeks.
Filiform papillae
broadly divided Into three categories based on Most of the tongue is
the number of taste buds on their tongue. Those covered in thin, rough
bumps that contain no Anterior tongue
with the fewest are known as 'non-tasters', those taste receptors. The visible part of the
with an average number are known as 'tasters', tongue is responsible for
and those with many more taste buds than the the majority of taste
rest if the population are 'supertasters.' detection.

Supertastersare espedally sensitive to taste and

will react much more strongly than the rest of Gustatory hair
the population. As a resu It, they tend to really 1UII!C'B I SAlE Each taste cell ends with a
.uaDE.VERY tiny hair, covered in
dislike bitter foods llke green vegetables and TDIIM'IIS receptors that allow it to
coffee, and often shy away from rich desserts detect chemicals dissolved
and s ugary sweets. in the saliva.
Though these anatomica I differences can What is a
explain some of our food preferences, most our Basal cell
individual likes and dislikes are not down to
taste bud? Ageing or damaged
taste cells are replaced
taste, but to flavour; the combination of taste and Pore
by the basal cells
A tiny gap at the top of the
smell. The act of chewing food releases taste bud allows saliva to waiting underneath.
chemicals known as volatiles, which evaporate touch the taste cells.
rapidly. As we swallow, some of the air inside the
mouth is forced up toward the nose, carrying Sensory cell
Support cell Each cell is sensitive
these volatiles with it Here, they bind to The taste cells are to one of the frve
receptors on olfactory cells, triggering sensory surrounded by an tastes, but au types
messages to the brain. envelope of non-tasting are found together in
support cells. a single taste bud.
Recently, sdentists have found that these
olfactory receptors ca n detect as many as 1
trillion different odours. Taste and smell are Synapse Nerve
Taste cells do not transmit the Messages are relayed
strongly linked to emotion and memory, and as a to the brain via a nerve
signals to the brain themselves,
result, experience Is a powerful decider in the instead passing the message that exits at the bottom
development of our II kes and dislikes. over to a nerve ceiL of the taste bud.

092
I•U•T'OOI!/I!W•lr.'i? Stomach ulcers were long thought to be caused by stress. but it's now known the culprit is o bacterial infection

Inside the Oesophagus

Food travels from the
Fundus
Excess gas is collected at
Rugae
The lining of the stomach

stomach mouth to the stomach the top of the stomach, is stretchy and expandable,
via a muscular tube where it can be pushed out and when relaxed, it curls
that runs behind and up by the diaphragm. up into characteristic folds.
the windpipe.
This muscular bag turns your dinner
into an acidic soup Body
The central portion of the
The stomach acts as a holding chamber, stomach helps to create
receiving food from the mouth and preparing it downward pressure,
Cardiac keeping food moving in the
to be processed in the s mall intestine. At rest, the sphincter right direction.
A ring of muscle at
stomach is around the size of a fist, and its lini ng
the top of the
is curled into a convoluted network of folds stomach stops the
Muscle layers
known as rugae. As you eat, these folds stretch acidic contents
There are three
moving back into
out, allowing an adult to eat around a litre (0.26 layers of muscle in
the oesophagus.
gallons) of food In one sitting. Stretching of the the stomach wall,
each running in a
stomach walls triggers rhythmic contractions, different direction.
mixing the food with acid and protein-digesting Antrum
The bottom part of
enzymes, grinding it to a paste in preparation for the stomach
the next stage of digestion. generates powerful
grinding
contractions.

Duodenum
The stomach
empties its
contents into the
first section of the
small intestine.

Pyloric
sphincter
A ring of muscle at
the base of the Stomach lining
stomach prevents The lining is covered in
the contents from microscopic pits that
leaking out before produce mucus, acid and
they are ready. protein·digesting enzymes.

Chewing
the fat
Fat has a bad reputation, but
the truth is, your body needs it
Every single cell in your body is
surrounded by a membrane made of
fats; it insulates your nerves and it
provides a valuable energy reserve.
Eating fat also provides a number of
vitamins and essential fatty acids
the body can't make on its own.
Saturated fats (the sofid fats found in
meat and dairy) and trans fats
(found in hydrogenated vegetable oil
and many processed foods) have
shown to raise cholesterol, which
can lead to circulatory problems, but
unsaturated fats (the liquid fats
found in plants and fish) can have
the opposite effect. and are
considered good for your health.

093
 =··
Toste and digestion

4,soorrr
'IIE'IUIIIIJPDL IU
large intestine
The second part of lhe
inlPstine absorbs water
Brush border
The cells that make up lhe
intestinal wall are covered
Villi
The cells that line lhe walls
5I f 2 "AIEACIF'IIE and prepares waste. in microscopic fingers of lhe small intestine are
known as microvilli. arranged into folds
known as villi.

Small intestine
The first part of the
intestine is responsible for
breaking food down and
absorbing lhe nutrients.
Appendix Rectum
Near the start of the large Before exiting the body,
intestine is a blind-ending tube waste products are stored
known as the appendix - its In a small pouch known as Small vein
fLOICtion is largely unknown. the rectum. Nutrients travel across
the wall of the intestine
into the blood stream.
Small
Lymph vessel artery :_______ Intestinal crypt
Fatty acids are transported Each of the Between the villi are
away from the intestines via villi has a rich crypts containing

The intestines
After leaving the stomach, food must pass through over 7m (23ft) of intestines
the lymphatic system. blood supply. mucus·producing cells.

The stomach contents enter the intestine are added by the pancreas. The enzymes act like small intestine. The remaining undigested
gradually, allowing tlme for the liquid food to be molecularsdssors, breaking proteins, materia l passes into the large intestine, which
processed. Flrsttheadd Is neutra lised by bile, carbohyd.rates and fats down into building blocl<s absorbs water, leaving behind solid waste that
provided by the liver, and then digestive enzymes small enough to be carried over the wall of the can then be passed out ofthe body.

094
 • •
• •
STOP Eight glasses of water
1Drinking plenty of water is
· Vitamin Cstops colds
:2
• In trials involving over 11,000 •
Canvt night vision
3 Calt'ots contain vitamin A,
Celery's minus-calories
•• 4 1t is a popular fact among
•
••
Chocolate causes acne
5
Actually, tl"is one rright be

FACTS
FOOD MYTHS
benellclal for 01.1' health, but
there is nothing special about
drinking eight glasses. Drinking
when you feel thirsty is usually
•
•
••
people, it has been shown that
vitamin C does not prevent or
cure colds. However, washing
hands regularly is effective at
v~al for eye health, but the
idea that they help you see in
the dark Is a lie from WWII to
keepradartechnologysecret •
dieters that eating celery
bums moc-e calories than it
provides. Although possible in
theory, no foods have been •
true. Ne'IN research is
increasingly suggesting that
diet does have an impact on
acne and that saturated fats
more than eoough. preventing transmission. from the Germans. found to have this effect. • and sugars might be to blame.
DEBUNKED • • •
-
!•lf•M!I!llW1•1~W The human mouth produces 1-2/itres of solivo every doy

The first part of the digestive system prepares washing-up liquid, separating the fats out into can sometimes convert one into another if
the food for the next stage, ensuring it is broken smaller blobs. supplies are running low. However, there are a
into a fine paste, mixed to form a homogenous Now that the food is nicely mixed and number of nutrients that cannot be synthesised
fluid, and shocked with add to limit the separated, the enzymes can really get to work. by the body at all or in high enough quantities,
potential for dangerous infection. However, it The pancreas produces a cocktail of three and these must be obtained directly from the
is not until food reaches the small intestine kinds of enzyme, each used to break down a diet. These essential nutrients include some
that the microscopic breakdown and different type of molecule. Proteases clip types of amino adds, fatty adds like omega-3
absorption of nutrients really begins. amino acids from proteins, lipases break fats and omega-6, and all of the vitamins and
At the start of the small intestine, the liver down into fatty adds and glycerol, and minerals needed.
injects alkaline bile into the acidic liquid food, carbohydrases turn long chains of Vitamins and minerals are organic and
neutralising its pH and preparing it for the carbohydrate into sugars. These small blocks inorganic compounds required by the body in
introduction of digestive enzymes. can be absorbed into the bloodstream, where small amounts for various different functions.
Bile also helps to emulsify fats. Fats are not they are distributed around the body, used to Some of these, like calcium, make up vital
water soluble, so they tend to clump together in build our own biological molecules, or broken structural components of our bodies, while
large globules to hide from and avoid the down and burnt for energy. The body requires others, like vitamin C, are involved in
surrounding water, but bile acts a little like different quantities of each of the nutrients, and biochemical reactions.

IRON-RICH FOOD Iron is a key component of

haemoglobin, the red pigment that
carries oxygen in our blood.
Without it, oxygen cannot be
transported effectively, result ing in
iron-deficiency anaemia. This is
most often caused by blood loss,
z so as a result, women are much
0 more likely to be deficient of iron

-
0::
Egg yolks Red meat
than men.

GREEN LEAFY VEGETABLES Folic acid is essential for the

synthesis of DNA and w ithout it
the production of red blood cells
starts to slow down. It is also
extremely important in the
formation of the central nervous
system, and during the first 12
weeks of pregnancy, folic acid
supplementation is recommended
to pregnant women.
Broccoli

OILY FISH Vitamin D is involved in bone

formation in t he body, so
deficiency of vitamin Din
0 children can result in bone

-z~
deformity. Luckily, this vitamin is
easy to obtain. Not only can
vitamin D be found in oily f ish,

->~
eggs and dairy product s, but our
bodies can also make it
t hemselves using sunlight.
Salmon Tuna

FRUITS Cells use a combination of

potassium and sodium to maintain
~ their internal electrical balance.

-~
;::) Potassium is vital to ensure
muscles are able to contract
properly and nerves are able to
transmit their messages. It is
~ easily obtained in the diet and
0 deficiency is incredibly rare unless
a.. Dried apricots Avocados
there is damage to the kidneys.

095
 =··
Hunger is one of the body's
most basic and Food addiction
fundamen tal sensations, Research into food same reward pathway that lights up when
and it originates in the addiction is relatively addictive drugs are ingested. In alcoholics,
stomach. When the new and the results cocaine addicts and heroin addicts, the
stomach is empty, it begins are hotly debated, but number of dopamine receptors in the reward
to produce a hormone there is increasing pathway is lower than in the rest of the
known as ghrelin. This then evidence that food can population and the same thing is found in
travels to a region of the brain elicit some of the same obesity. It is thought that people with fewer
known as the hypothalamus. brain responses as addictive dopamine receptors might need to over-
Th e hypothalamus is responsible substances ill<e cocaine.ln stimulate their brains to experience the
for maintaining a constant, optimum state; overweight people, overeating can same rewards as normal people, and
keeping the body at a set temperature, regulating become a compulsion that is difficult to therefore turn to alcohol, drugs, or perhaps
hormones and monitoring hydration. The arrival control, and has b een shown to activate the even food.
of ghrelin is a signal that energy levels might be
about to dip, so it triggers the production of a
second hormone, neuropeptide Y. This hormone
p romotes eating.
The cue to stop eating is much more subtle. The
stomach has stretch receptors, and will signal to
the brain that it is full. But what happens if it is
empty, but there is already enough energy stored
in the system? fat stores produce a hormone
known as leptin, which tells the brain exactly

Food and the brain

Why do we crave these foods?
how much energy the body has in reserve. When
leptin levels a re high, the hypothalamus makes
hormones that suppress appetite.
The trouble is that with high levels of fat, we
can become resistant to th e leptin message,
similar to insulin resistance in type-II diabetes. If
the brain does not know there is enough fat, we
just keep eating.
Cravings are slightly different. These are
generated not in th e stomach, but in the brain.
There are three main areas ofthe brain
implicated in food cravings, the hippocampus,
the insula and the caudate.
Humans have been programmed through
evolution to enjoy fatty a nd sugary foods; eating
them ensu res we have enough energy to su rvive.
The hippocampus is involved in gathering
sensory information, and processing it for
long-term memory storage, and with food
cravings, these memories become associated
with activation of the brain's reward circuitry.
The more we enjoy eating a food, the more likely
we are to crave it.
Mental images are thought to play an
important role in food cravings and picturing
food makes it much harder to resist. But thinking
about other visual images can help to curb the
cravings and distract your brain.
Digestion happens subconsciously, but you do
have a manual override, and what your brain
thinks it wants isn't always what it needs.

096
 Answer:
STRANGE How long does chewing It is ttue that chewlllQ: gum cannot be digested.

BUT TRUE gum stay in your system? but as &ong as It is a small piece - less than 2cm
(0.81n) in diameter - there is no reason it should
get stuck, and It should pass out oonnally within
A STICKY MYTH A Seven years 8 A day C Forever adayottwo.

[•!(17\X!IDt:W•~W The digestive system hos its own dedicated neNous system, known os the enteric neNous system

Tea Chocolate
In England, drinking tea is a national pastime. The main chemicals in tea are Chocolate is one of the foods most commonly
known as polyphenols, and each cup contains around 200 milligrams (0.007 associated with happiness, particularly the
ounces). The polyphenols are large molecules made up of smaller building hormone serotonin. The chocolate itself does
blocks, which are known as catechins. When these catechins react with contain the precursor to serotonin, an amino acid
oxygen, they make two types of chemical; theaflavins, which make the known as tryptophan, but this is also found in
orange-brown colour of tea, and thearubigins, which are thought to many other foods, including meat. Chocolate also
contribute to the taste. The different amounts of the contains phenylethylamine, a molecule
chemicals present in the tea are chemically similar to amphetamine, but it is
very dependent broken down in the digestive system, and
on the life of the does not reach the brain intact. The
plants and the feel·good factor of chocolate is
processing of more likely to be down to its fat
the leaves. and sugar content, and a
property known as mouthfeel.
Chocolate is among the only foods
that melts at close to
body temperature.

I
TIE IBIGTH OF AN
I AVEIWlE S1UMIICH

l
AFTER A NEAL

Coffee
Coffee contains over
1,000 different aroma
compounds, responsible
for its unmistakable smell.
Around 12 per cent of the green Bacon
coffee bean is made up of a set of
chemicals known as chlorogenic acids, and when the beans are
The distinctive smell of bacon is, as most of us have probably
experienced, hard to resist. That fact is all down to the chemistry of
J
!
roasted, most of these acids begin to break down. Some produce cooking meat. As the bacon is heated, the amino acids that make up ~
the brown-coloured compounds that give coffee its characteristic the muscle protein react with reducing sugars present in the bacon "
dark colour, while others produce the bitter-tasting chemicals fat. This process, known as the Maillard reaction, occurs only at high ~
responsible for its taste. Coffee also contains high quantities of temperatures and produces over 150 different volatile molecules, ~
caffeine, around 100 milligrams (0.0035 ounces) in every cup. It each able to interact with different smell receptors in the nose. Most
!!'
"
works on receptors in the heart and brain, blocking the action of a
natural neurotransmitter and acting as a stimulant.
of the delicious smell of bacon is attributed to a group of nitrogen·
containing compounds known as pyridines and pyrazines.
!
G

097
 =··
blood- brain barrier

-
•
ra1n
How does this gateway control the molecules
that pass from the blood into the brain
The blood-brain barrier (BBBI is an
essential group of cells that line the Breaking down the barrier
blood vessels In the central ne rvous This built-in gateway is the main line of
defence for the central nervous system
system (brain and spina l cordi.
They allow passage of materials between the
clear Ouidsurroundlng the brain (cerebrospinal Just passing through
Ouid) and the red blood cells in arteries. veins Some ions are transported
out of the blood cells and
and capillaries. The key advantage of having into the astrocytes, and then
such a barrier is that It prevents large micro- out of the astrocytes and
organisms passing into the brain and causing into neurons in the brain.

infections. While infections in other areas are

common (such as after a cut finger. or mild chest
inJections), those affect! ng the brain are much
rarer. However when they do occu r (eg Upophilic
meningitis), they are potentially life Substances rich in
threatening as they are very difficult to treat. lipids can diffuse
across the barrier
The tight junctions between cells regulate with relative ease.
the size and type of particle that pass between
them, including oxygen molecules, carbon
dioxide molecules, nutrients and hormones.
Since it's so effective, It also stops medications
from entering the brain (such as certain
antibiotics), so while they are effective in the
rest of the body, they are Ineffective in this vital
organ. Overcoming this is a major aim of
doctors in the next decade, and the battle has
Astrocyte ----·:>~~~:,e;T~~~
already s tarted. Ma nipulati ng the blood-brain These numerous
barrier's natural transport mecha nisms and star-shaped cells provide
biochemical support to the
delivering drugs within nanoparticles to endothelial cells, and also
squeeze throug h the tightjunctionsa rejust play an Important role in
two examples of the modern techniques that transportation and repair.

are under development.

Special transport
Crossing the BBB Active and passive
transporters across this
The endothelial lining of the blood·brain barrier membrane can overcome
loves lipids (fatty molecules), but it hates some or these problems,
particles with high electrical charges (ions) and and be manipulated to
large substances. Thus the ideal substance is deliver medications to
small, rich in lipids and has a low electrical the correct place.
charge. Barbiturates are such an example, as they
freely flow across the blood· brain barrier to
suppress brain function; they act as sedatives and
antidepressants. However this free movement Highly charged A tight squee.ze ~
comes with risks - too much of it will accumulate Highly charged ions are The tiny gaps between ~

and slow the brain to a point where you can lose repelled, meaning that cells regulate the size j
and type of particle that ~
consciousness and even stop breathing. some medications are
ineffective in the brain. are able to fit through. Q
...

098
RECORD TAll EST MAN IN HISTORY
At 2.72 metres (eight foot, 11.1 inches) Robert Wadlow is the tallest man
BREAKERS
TALL TALE m on record. Asufferer of gigantism, he was 0.9 metres (three feet) taller
than his father. Sadly, he was only 22 when he died in 1940.

!•Jf•J\t!I!ll;W•1~W In fish, the intermediate lobe controls skin co/our change, while birds hove no intermediate lobe at all

ituita ose
What does this hormone factory do and why couldn't we live without it?
The pea-sized pituitary gland is
found at the base of the brain, close The master gland in context
to the hypothalamus. It looks a Where does this vitally important hormone
relatively insignificant part of the manufacturer sit within the human brain?
brain, but it plays a role in many vital systems.
Often referred to as the 'master gland', it not Hypothalamus
only releases hormones that control various The seaetion of hormones
from the pituitary gland is
functions, but it also prompts the activity of directly controlled by this
other gla nds like the ovaries and testes. part of the brain, which
The pituitary gland comprises three sections links the nervous and
endocrine systems.
called Jobes: the anterior, the posterior and the
intermediate - the latter of which is considered
part of the anterior lobe in humans. These work
together with the hypothalamus, which
monitors hormones in the blood a nd stimulates Pituitary stalk
the pituitary gland to produce/release the This is what connects
the pituitary lobes to
appropriate hormone(s) if levels fall too low. the hypothalamus.
The anterior lobe produces seven important
hormones, which include those that regulate
growth and reproduction. Adrenocorticotropic
hormone (ACTH) targets the adrenal glands to
produce cortisol and controls metabolism, Posterior lobe
while lutein ising hormone triggers ovulation in This doesn't produce any
women and stimulates testosterone production hormones itself, but
stores and releases some,
in men. The posterior lobe, meanwhile, doesn't like ADH, made elsewhere
generate any hormones itself, but stores two: in the hypothaJamus.
antidiuretic hormone (ADH), which decreases
urine production by making the kidneys return
more water to the blood, and oxytocin, which
tells the uterus to contract during childbirth
a nd also prompts milk production.

Capillaries
Gigantism in focus Hormones are exchanged
between the anterior lobe
The pituitary gland also produces growth and the hypothalamus via
hormone, which in adults controls the amount a networi< of capillaries.
of muscle and fat in the body and plays a key
role in the immune system. In children, of
course, growth hormone has a very noticeable
ef fect in increasing height and bulk until
adulthood. However, sometimes the pituitary
gland becomes hyperactive - often as a result of Anterior lobe
a benign tumour - and produces excess growth Subdivided into three
hormone. In these cases, a person can grow to a parts, including the thin
far-beyond·average height, with hands, feet and intermediate lobe, this
facial features growing proportionally. While this produces s"""" kinds
might not seem so bad, gigantism is nearly of hormone which each Thyroid
always accompanied by other health issues, target specific organs. One of the largest
such as skeletal problems, severe headaches endocrine glands that
and more life· threatening conditions like heart regulates metabo~sm
disorders. If diagnosed early, treatment such as is in turn regulated by
drugs that inhibit growth hormone production the pituitary gland.
and surgical removal of the tumour can help
avert the more serious conditions of gigantism.

099
 =··
the brain
I , ._,... uce
enough c
power a light
The brain is a complex and extremely powerful organ, but
would it be strong enough to power any everyday fightbulb?
The brain itself requires a relatively low neurons are signalling and in a highly synchronised
power to operate on a day-to-day basis, manner, the generated electric fields are large enough
around 20 watts which would be enough to to be detected outside of the skull through
power a very weak light bulb. zawatts electroencephalography ~EEG) or
corresponds to zo joules ol energy per second. The magnetoencephalography ~MEG).
generation ol electricity In the brain results from the
movement of ions ~charged atoms) throughout the
brain, as opposed to electrons moving through a wire. "The generation of.
Interestingly, a unique side effect of the brain's
electrochemical processes Is that Is generates electric
electncity results from
fields when it is active.! ndeed, when large numbers of the movement of ions"

Ongoing message
Once the neuroaansmltlers
cross the gap between the two
neurons, ion channels in the
receMngneuronopenallowlng
the poslllveloos In flow into the
receiving neuron.

100
 • • •• •
Welcome to the wortd : When you need to breathe : And relaaax • Amino what now? •• F"19ht or flight
5 TOP- 1 Ababy's stress level dumg
birth is high and, as a result.
•2
!
Due to its blooc:I"Vessel·
•
•• 3 After stressful situiJt~ it's :4 Adrenaline can be obtained from
••
5The sayw.g 'fight or 15ghr ;,

FACTS
constricting properties. adrenaline often a good idea to physically : animals orsynthesised in the tJb. associated vMh adrenaline because
their actenaline level is also is also used to treat breathing •• wort<. off the adrenaline in your • The chemical name fa it is when we're stressed we produce the
\lei)' high at this time. This difficulties associated with
•• body so it doesn't stay in your ••• aminohydroxyp~ic
•• hormone in order that we can either
• •• •
•••
subsides post birth back down anaphylactic shock caused by system, keeping )'OU awake at acid, v.'hich is represented with the get ready to ~Efend oorselves or
ADRENLINE to normallevets. • alergic reacOOns.
•
•• n9>~ for example.
•
chemical form1JaC9Hl3N03. ••
•
make a run for iL

li Medulla - - - - - - ,
At the core of the
adrenal gland, the
adrenal medulla
. - - - - - - - - -Cortex
At the edge of the adrenal gland, the
cortex produces steroid hormones that
include cortisol (for balancing blood sugar

Discover the science behind your bodys produces, stores and

releases adrenaline.
and carb metabolism) and aldosterone
(for balancing the body's salts and water).
amazing chemical coping mechanism
Nestling on a layer of fat as adrenaline. Identified in 1900, . - - - - Kidney
located justabove each adrenaline is a fast-acting hormone The organ that
of your kidneys are the that helps the body deal with filters waste
from the blood.
body's adrenal glands. unexpected stresses- not to mention
Around Scm long, the adrenal glands high levels of excitement - by upping
produce hormones that affect your your heart rate and the flow of blood
body's consumption of energy as well to your muscles. r - - - Fat
Each adrenal
as your stress responses. The effect of this is that your blood gland is protected
Adrenal glands consist of two main vessels and air passages dilate, by a layer of fat.
layers ofhormone-secreting cells: the meaning that more blood passes to
outer cortex and the inner medulla the muscles and more oxygen gets to
While the cortex produces energy- the lungs quicker, temporarily
balancing hormones, the medulla improving the body's physical
produces a chemical called performance and potentiallysaving
epinephrine, which we know better your life.

"Adrenaline is o fast -acting

hormone that helps the
body deal with stresses"
101
 =··
ow we breathe

Respiration is crucial to an organism's

survival. The process of respiration is the
transportation of oxygen from the air that
surrounds us into the tissue cells of our
body so that energy can be broken down /
The primary organs used exercising, breathing rate increases L Nasal passage/
for respiration in humans and consequently so does heart rate oral cavity
are the lungs. Humans to ensure that oxygen reaches tissues These areas are wllere air
have two lungs, with the that need IL Oxygen is then used to enten into the body so that
axyge<1 can be tr.lnsi>Orted into
left lung being divided Into two lobes break down glucose to provide
and around the body to wllere
and the right into three. Lungs have energy for the body. This happens in
it's needed Carbon cloxide
between 300-500 milUon alveoli, the m ltochondria or cells. Carbon
which is where gas exchange occurs. dioxide Is one or the waste products
also exls tlrough these areas. • .,.
)
Respiration or oxygen breaks Into
four main stages: ventilation,
of this, which iswhywegeta build up
of this gas In our body that needs to
• ..... ..
pulmonary gas exchange, gas be transported back into the lungs to
transportation and peripheral gas be exhaled. •
{
exchange. Each stage ls crucial in The body can also respire .r
•
getting oxygen to the body's tissue, anaerobically, but this produces far i j
and removing carbon dioxide. less energy and Instead or producing
Ventilation and gas transportallon cozasa byproduct, lactic acid is
need energy to occur, as the produced. The body then takes time .... •
diaphragm and the heart are used to to break thlsdown after exertion has
faciUtate these actions whereas gas finished as the body has a so-called
exchanging is passive. As air Is drawn oxygen debt.
Into the lungs at a rate of between 10-
zo breaths per minute wh lie restl ng,
through either your mouth or nose by 5. Alveoli - -
The alveoli are lily fittle sacs which are situated
diaphragm contracllon.•and travels at the end of !OOes inside the lungs and are in
through the pharynx, men the direct contact with blood. Oxygen and carbon
larynx, down the trachea, and Into dioxide transfer to and from the blood stream
one ofllle two main bronchial tubes. through the alveoli. - -
Mucus and cilia keep the lungs clean
by catching dirt particles and
sweeping them up the trachea.
When air reaches the lungs, oxygen
is diffused into the bloodstream
through thealveoU and carbon .• • •
y •
•
dioxide is diflused from the blood • • • •
into the lungs to be exhaled. Diffusion •
•

How our
ofgasesoccursbecauseofdifferlng
pressures in the lungs and blood. This
isalsothesamewhenoxygen
difluses into tissue around the body.
When blood has been oxygenated by
the lungs, it is transferred around the
work
body to where ills most needed In the Lungs ore the major
bloodstream. If the body Is Capllary beds respiratory organ in humans
102
 - -
•• •
•
•
•
•
•
•
~ c;qJaCi:ty • The rightlung We have excess Alveoli have massive • We breathe 11,090
STOP 1
vanes hUgely
•
• is bigger
••• 2
• lamg capacity
•
:3
: surface area
4
•
• litres of air per day
•• s On average, one individual will
FACTS Dependant on sex a1d body lntere:stiogly, the lefU .1ng is On average. t.Jmansonly use tf one person's entire
size. alongside external • slightly smaUer than the ri!;#lt in • about one-ei~ of the ! alveoli were &aid out they would breathe in 11.000 itres of air in
factors such as altitude, lung •• the human body because the left • capacity of our lungs fOt'each • have the surface area of about 70crnl any given day.lf they exercise
• •
capacity ranges between • lung has to make room for the • breath so we have a large ! ... that's roughly the size ofhatf a • he<Miy during 111at day, this will
•• •• ••
LUNGS 4,000and6,000an'.
• heart to fll in. reserve volume. • tennis court!
• increase fLI'ther.

!•U•I\1•1!/Itj~I•IW Trained free-divers con hold their breath underwater for up to nine minutes

Chest cavity
This is part of both
the respiratory and
digestive system. A flap
of coonectilie tissue
How do we breathe?
The intake of oxygen into the body is complex
This is the space that
is protected by the
rils, w here the lungs
and heart are
situated. The space
called the epiglottis
Breathing is not something that we have to the alveoli at the ends, which are the final changes as the
closes over the trachea
to stop choking when think about, and indeed is controlled by muscle branching. The chest will be seen to rise diaphragm 111011es.

an incfrvidual takes food contractions in our body. Breathing is because of this lung expansion. Alveoli are
into their body. controlled by the diaphragm, which contracts surrounded by blood vessels, and oxygen and
3.Trachea and expands on a regular, constant basis. carbon dioxide are then interchanged at this
Air is pulled into the When it contracts, the diaphragm pulls air into point between the lungs and the blood. Carbon
body through the nasal the lungs by a vacuum-like effect. The lungs dioxide removed from the blood stream
passages and then expand to fill the en Ia rged chest cavity and air that was breathed in but not
.""';ses into the trachea. and air is pulled right through used is then expelled from the lungs
the maze of tubes that by diaphragm expansion. Lungs

____
.....:---._...._
makeup the
--....:.:.lungs to
deflate back to a reduced size
when breathing out.
Lungs
Deoxygenated blood
arrives back at the
lungs, where another
gas exchange occlS"S at
the alveoli. Carbon
dioxide is remOIIed and
4. Bronchial tubes oxygen is placed back
•• These llbes lead to either the
into the blood
left or the right lung. Air passes
through these tubes into the
lungs, where they pass
Diaphragm - - - - - - '
•t:, through progressiwly smaller
This is a sheet of muscle situated Ribcage
at the bottom of the rib cage This is the bone
and smaler tubes until they
which contracts and expands to structure which
reach the alveoiL
•'·•'
<{
draw air into the lungs. protects the organs.
The rib cage can
•• Heart move slightly to
The heart pumps oxygenated alow for lung
blood away from the lungs, expansion.
around the body to tissue,
where oxygen is needed to
break down glucose
into a usable form

- 6.Ribs
These provide protection
of energy.

for the lungs and other Tissue

internal organs situated Oxygen arrives
in the chest cavity. where energy is
.•• needed, and a gas
exchange of
oxygen and carboo
dioxKie occurs so
that aerobic
respiration can
occur within cells.

I ' do we oxygen?
We need oxygen to live as it is crucial for the release
•
' . of energy within the body
'I •
'• Although we can release energy through more thana few minutes, anindividualwill die.
anaerobic respiration temporarily, this method Oxygen is pumped around the body to be used
Is Inefficient and creates an oxygen debt that in cells that need to breakdown glucose so that
the body must repay after excessexerdse or energy is provided for the tissue. The equation
exertion has ceased. If oxygen supply is cutoff for that illustrates this Is:

.__ _____..
103
 =·· drotion
I

Pore
Sweat is Skin
released directly Once the sweat is on the skin's
into the demlis ...-face. its absorbed moisture
Ilia the sea etaoy evaporates,
c1JC1. wl1ich then heat into ·the afro'fi:'lre
filters IIYough
the skin's pores
to the surfaoe.

do we
As your doctor may tell you, it's glandular...
Sweat Is produced by dedicated sweat internal temperature of the body rises, secrete a
glands, and Is a mechanism used salty, water-based substance to the skin's surface.
primarily by the body to reduce its This liquid then cools the skin and the body
Internal temperature. There are two through evaporation, storing and then transferrl ng
types of sweat gland In the human body, the excess heat Into the atmosphere.
eccrine gland and the apocrine gland. The former Both the eccrlneandapocrinesweatglands only
regulates body temperature, and Is the primary appear in mammals and, ifactive over the majority
"'Qc
source of excreted swea1.. with the Iauer only of the animal's body, aetas the primary
secreting under emotional stresses, rather than thermore.g ulatory device. Certain rna mma Is such
Secretary Secretary part Nerve fibres
duct This is where the DeiNer messages to
those Involved with body dehydration. as dogs, cats and sheep only have eccrine glands In majority of the glald's
Secreted sweat glands to produce
Eccrine sweatglandsarecontrolled by the specificareas-suchaspawsand lips-warranting tnM!Is up to the secretary eels can sweat when the
sympathetlcnervoussystemand, when the the need to pant to control their temperature. skin Ilia this cb:t. be located. body's temp rises.

a concentration of
particles in the
blood, indicating a

Other symptoms at
this level include
fatigue, a dry mouth

include sunken
nowsose~~ere eyes. low blood
that IV fluid
Too much H2 0? replacement
Hydration is all about finding the perfect balance.
Too much hydration can be harmful as well as Here symptoms
too little; this is known as water intoxication. If become much
too much liquid is in your body, nutrients such
as electrolytes and sodium are diluted and the cognitive abilities
body suffers. Your cells bloat and expand and
can even burst. and it can be fatal if untreated.
The best treatment is to take on IV fluids
containing electrolytes.
 •• • • ••
•• Mental state : Latinname • The 6ving dock • nme to take your pills
STOP Jet lag
l rme zone changes can often •
•
••
2 Heatthoonditions such as
•
•
••3 With these rhythms known to
•
•4 In the 18th Cenh.ry, a botanist •
••
s Doctors teUyou to take medicine

FACTS disrupt circacian rhythms.

Y011body clock may beoul
of sync with your wristwatch,
•
••
depression, bipolardisorder
and seasonal affective
disorder (SAO) are all
•
••
OCCIX approximatelyf?t~e~Y 24
hours. the phrase 'circadian'
stems from Latin for •circa",
•

••
called CarolusUmaeusis said
to have invented a iving d ock.
His garden coukf help him tell
••
••
at a prescribed time because the
l"l.lmanbodydock can affect
their effecti\'eness. Aspirins
CIRCADIAN but it will reset itself after a
•
• associated with abnormalities
•
• which means 'about', and 'diem'. •
• the time based on the flowers • function better when taken earty
RHYTHMS ••
few days. i'l circadian rhythms.. • which means 'day'. • he planted. • in the morring.
• • • •

t•U•I'\JII!IItj~l•l!l!LP The pineal gland, located near the centre of the brain, is about Bmm long and shaped like opine cone

How does our internal body clock tell us when to sleep?

NOON
12.00
!::~~
The variations the amount of
in
10.00
09.00 High alertness melatonin secreted by the body create
Highest testosterone 14.30 a daily rhythm of rising and falling
secretion here Best co-ordination
hormone levels. These hormones,
along with the SNC, affect appetite,
08.30 body temperature and a lot else.
Bowel movement likely
15.30
Fastest reaction time

07.30
Melatonin secretion ends

06AS
Steep rise in blood
pressure. Heart attacks
are more likely to ace..- in 17.00
the morning than any Highest cardio-
other time due to this rise vascular effkiency
in blood presst.re and muscle strength

06.00 18.00
18.30
Highest blood
pressure time

04.30 19.00
To conserve energy during Body temperature is
sleep, body temperature highest during the
drops. It is at its lowest just late afternoon
before waking

21.00
With the fading of sW~Iight into
the evening, melatonin secretion
begins - and increases tenfold -
02.00 22.30 mak ing us sleepy
Deepest sleep Bowelm~
00.00 suppressed here
MIDNIGHT

Circadian rhythms are biological changes that occur at roughly 24-hour

intervals, wbetherwe're aware of the time on our watch or not. These
changes, which are controlled by Internal biological time-keeping
systems, affect us physically, mentally and behaviourally.
Located behind the eyes in the hypothalamus is a region of the brain called the
suprachlasmatic nucleus. No larger than a grain of rice, the SCN is a kind of master
body clock that controls all our other internal clocks, which in turn control our
circadian rhythms, or daily wake-sleep cycles. Circadian rhythms respond mainly
to light and dark cues but even if the body was monitored under conditions devoid
of day or night signals, our circadian rhythms still cycle in a period of around24
hours. The retina In the eye senses light level information, which is relayed to the
SCN, which sends a signal to the pineal glancl Thispea-si2ed gland, located
beneath the thalamus, is responsible for the secretion of melatonin - a hormone
that tells the bodytosleep- andsoat nigbtwhen lightlevelsfall, the production of
melatonin increases, telling us to head to bed...

105
 umon immune system

Human anatomy subscribes to the notion

that good fences rna ke good neighbours.
Your skin, made up of tightly packed cells
and an antibacterial oil coating, keeps
most pathogens from ever setting foot in
body. Your body's openings are well-
fortified too. Pathogens that you inhale
face a wall of mucus-covered membranes
in your respiratory tract, optimised to
trap germs. Pathogens that you digest end
up soaking ina bath of potent stomach
add. Tears Hush pathogens out of your
Your body is locked in a constant eyes, dousing bacteria with a harsh
enzyme for good measure.
war against a viscous army
It's true: whileyou'resittingaround that take over host cells and replicate inside them; just about everything l.n our environment is
watching TV, trillions offoreign invaders and fungi, a type of plant life. teeming with these microscopic intruders... including
are launching a full scale assault on the Bacteria and viruses are by far the very worst you. The bacteria in your stomach alone outnumber
trillions of cells that constitute 'you'. offenders. Dangerous bacteria release toxins in the all the cells in your body, ten-to-one. Yet, your scrappy
Collectively known as pathogens, these attackers body that cause diseases such as E. coli, anthrax, and microscopicsoldiers usually win the day against
include bacteria, single-celled creatures that live to the black plague. The cell damage from viruses causes pathogens, through a combination of sturdy barriers,
eat and reproduce; protists, larger single-cell measles, the Ou and the common cold, among brute force, and superior battlefield intelligence,
organisms; viruses, packets ofgenetic Information numerous other diseases. collectively dubbed the immune system.

106
 •• • ••
• •
• It deals with internal •
• You can 'bonow'
STOP. 1
The are can
sometimes hart
• Immunity soldiers
: are everYwhere
:2
• immunity
:3
•
• troubles, too
••
4
•• It has trouble with
•
• change
:s
FACTS
IMMUNE SYSTEM
Sneezing, coughing, a sore
throat, and fe\'er are all common
meansol expelting pathogens. so
as amoying as they are, each
•

••
•
A single drop of blood contains
arol..nd 375,000 white blood
cells, and blood constitutes lor
sewn per cent of your total
••
••
Antibodies in breast mikgive
babies temporary immLW'lity
from diseases their mother is
invnune to, preventing
•
•
In addition to fighting
pathogens, T-<:eAs fight the
body's own cancerous cells and
some cancer ther apies boost
:
•
•••
Unfortunately you cannot
develop inv"nulity to the
ftu andoommoncold
because the viruses are
one is necessary. • bodywei~l infancy infection. • the rumber of T-cells. • always mutating.

!•U•Jtl•l!l!tj~!•mG> or Karl Londsteiner first identified the major human blood groups -A, 8, AS and 0 - in 1901

•
Fighting the g ood fight, and white blood cells are
system
right on the front line... 2. Bacterium antigen
These distinctive m olecules allow your
When a pathogen is tough, wily; The B-cells flood your body im mune system to recognise that the
or numerous enough to survive with antibodies, molecules that 4 .Engulfed bacterium is something other than a body cell
non-specific defences, it's up to either disarm a specific pathogen bacterium
the adaptive immune system to or bind to it, marking it as a target During the initial 3. Macrophage 1. Bacterium
clean up the mess. The key forces for other white blood cells. When inflammation react:iof\ These white blood Any bacteria that enter
in the adaptive immune system T-cells find their target, they Joel< a maaophage engu~s cells engulf and digest your body haw
are white blood cells called on and release toxic chemicals the bacterium. any pathogens they characteristic antigens
lymphocytes. Unlike their that will destroy it. T-cells are come across,
macrophage cousins, especially adept at destroying
lymphocytes are engineered to your body's cells that are infected
attack only one specific type of with a virus.
pathogen. There are two types of This entire process takes
lymphocytes: B-cells and T-cells. several days to get going and may
These cells join the action take even longerto conclude.AU
when macrophages pass along the while, the raging battle can
information about the invading make you feel terrible.
pathogen, through chemical Fortunately, the immune
messages called interleukins. system is engineered to
After engulfing a pathogen, a learn from the past While
macrophage communicates your body is producing new
details about the pathogen's B-cells and T-cells to fight the 7.Non-
matching 8-cells
antigens - telltale molecules that pathogens, it also produces Other B-<:ells, engineered to
characterise a particular memory cells- copies of the attack other pathogens,
pathogen. Based on this B-cellsandT-cells, which stay in don't recognise
information, the immune system the system after the pathogen is the antigen.
identifies specific B-cells and defeated. The next time that 5. Presented -
T-cells equipped to recognise and pathogen shows up in your body, bacterium antigen
battle the pathogen. Once they these memory cells help launch a After engulfing the bacterium, the
are successfully identified, these counter-attack much more macrophage 'presents' the
cells rapidly reproduce, quick ly. Your body can wipeout bacterium's distinctive antigens,
comrrunicating the presence of
assembling an army of cells that the invaders before any infection
the specific pathogen to B-cells.
are ready and equipped to take takes hold. In other words, you
down the attacker. develop immunity.
Vaccines accomplish the same 6. Matching 8-cell
The specific lk:el that 9. Memory cell
thing bygivingyou just enough
Non-specific pathogen exposure for you to
develop memory cells, but not
recognises the antigen. and
can help defeat the pathogen,
The matching B-<:ell also
replicates to produce
memory cells, w hich wil

defences
As good as your physical defence system is, pathogens
enough to mal<e you sick.
1-------
rapidly produce copies of
itse~ if the specific
bacteria ever returns.

.)....~ y
do creep past it regularly. Your body initially responds
with counterattacks known as non-specificdefences,
so named because they don't target a specific type How
of pathogen.

-r ~
After a breech - bacteria rushing in through a cut, for
example- cells release chemicals called inflammatory a -cells target and
mediators. This triggers the chief non-specific defence, destroy specific bacteria
known as inflammation. Within minutes of a breach, and other invaders

~
your blood vessels dilate, allowing blood and other fluid
to flow into the tissue around the cut
The rush of fluid in inflammation carries various types
of white blood cells, which get to work destroying
intruders. The biggest and toughest of the bunch are
macrophages, white blood cells with an insatiable
appetite for foreign particles. When a macrophage detects
~~~~;r.te ~-~ -~
called phagocytes
recognise the antibody
marker, engutf the
10. Antibodies
The plasma cells release
J 8. Plasma cell
-
a bacterium's telltale chemical trail, it grabs the intruder, bacteria, and antibodies, which The matching B-cel
engulfs It, takes it apart with chemical enzymes, and digest them. disable the bacteria by replicates itself,
spits out the indigestible parts. Asingle macrophage can latching oo to their creating marry
swallow up about 100 bacteria before its own digestive antigens. The antibodies plasma cells to fight
also mark the bacteria aR the bacteria of this
chemicals destroy it from within.
for destruction. type in the body.

107
 =··
umon tmmune s
•
I

L Tonsils
L~~~~
~:-~
=---------:;~~~1r~- ~
lymphocytes, wl1ich attad<
bacteria that get into the body
through yar nose or mouth.

2. left subclavian vein

Oneal two large veins that serve
as the re-entry point for lymph
r1!h.ming to the bloodstream.

3. Right lymphatic duct G. l ymph

Passageway leading from lymph vessels node d uster
to the right subclavian vein. -----------...:..0:~ Located along lymph vessels
throughout the body, lymph nodes

Disorders of fi~er lymph as it makes its wey back

into the bloodstream.

the· - - - 7.Left
lymphatic duct
S. Spleen Passageway leading from
An organ that houses white lymph vessels to the left

Who watches the blood cells that attad<

pathogens in the
stbclavian vein.

watchmen? body's bloodstream - - - ...__ _ _ 8. Thymus gland

The immune system !sa powerful set of Organ that prollides area for
defences, so when It malfunctions, It lymphocytes prodJced by bone

can do as much harm as a disease. rnarn:M' to mature into

specialised T-<:ells.
Allergies are the result of an overzealous
immune system. In response to
something relatively benign, like
·~1 r - - - - 9. Thoracic duct
The largest lymph vessel
pollen, tbe immune system triggers in the body.
excessive measures to expel the
pathogen. On the extreme end, a llergles
maycauseanaphylacticshock,a
potentially deadly drop In blood
pressure, sometimes accompanied by 11. Peyer's patch
breathing difficulty and loss of Nodules at lymphoid tissueSl.pporting
consdousness.lnautolmmune while blood eels that battle pathogens
disorders such as rheumatoid arthritis, in the i 1lesti 01 tract.
the immune system falls to recognise
the body's own cells and attacks them. 10. Lymph vessels - ~~t--- 12. Bone matTOW
Lymph collects in tiny capilaries, The site at all white blood
which expand into larger vessels. cell production.
Skeletal mliSCies move lymph
through these vessels, back into
the bloodstream.

ex1Jiained
Lymph nodes
filter out
pathogens moving
through your
lymph vessels
The lymphaticsystem is a network of Your immune system depends
organs and vessels that collects lymph on these .04-t-inchsweUingsto
- Ould that has drained from the fight all manner of pathogens.
bloodstream into bodily tissues - and As lymph makes ilsway
returns It to your bloodstream. Italso through a network of fibres in
plays a key role in your immune the node, white blood cells
system, filtering pathogens from filter it, destroying any
!nan allergic reaction, the body may reson to
sneezing to expel a fairly harmless pathogen
lymph and providing a home-base for pathogens they find.
disease-fighting lymphocytes.

108
 1. Influenza 2. Measles 3. Tuberculosis
The nu kills hundreds of One person infected with Excavated Ancient Egyptian
thousands of people In a measles will sptead the virus mumfries show signs of
good year. And evory to just about every tuberculosis, and the disease
once in a while, a virulent unvaccinated petson they Is still thriving today. Around
form CaJl take out tens of e.ocounte(.luckily, the 2 billion people around the
miJIJons of people. vaccine is ve:ry effective. w<rid are infected.

!•U•I\1•1!1!tj~l•lmP In 2008, approximately 33 million people worldwide were living with HIV or AIDS

Know
inner contents enemy:

Bacteria are the smallest and, by far, the most populous form oflife
on Earth. Right now, there are trillions of the single-celled creatures
crawling on and in you.ln fact, they constitute about four pounds of
your total body weight. To the left is a lookat bacteria anatomy...

Major points of the lymph node

1. Outgoing lymph 7. Sinus
vessel Achannellhatslows the
--l4 The vessel that carries !lowoflymph,glvlng
llliered lymph out o1 the macrophages the
lymph node opportunltyto destroy any
2 . Valve detected pathogens
Astructure that prevents 8. Incoming lymph
lymph !rom !lowing back vessel
Into the lymph node Avessel that carries lymph
3. Vein Into the lymph node
Passageway lor blood 9. Lymphocyte
leaving the lymph node The T-cells, 8-cells and
4. Artery natural killer cells that
Supplyollncomlng blood fight lnlection
lor the lymph node 10. Genninal centre
5. Reticular fibres This Is the site or
Divides the lymph node lymphocyte multiplication
Into Individual cells and maturation
6. Capsule ll. Macrophage
The protective_ shielding Large whlle blood cells that
fibres that surround the enguUand destroy any
lymph node detected pathogens

109
 =··
ending bones

•
1n rocess
Learn how your body mends broken bones
If a bone has too much pressure put gradually fuse together, lil<e a bridge being
on it, there is a chance it will break. constructed from either side of a river until both
Your body has ways of repairing ends meet in the middle.
these breaks, but ittakes time and Once both sections of bone are connected
All-star cast
Most breaks on an arm or a leg will have a plaster
care. There are different kinds of break, ranging again, spedalised cells called osteoblasts enter to cast put on them to prevent the bone from
from a hairline fracture to a fully shattered produce bone cells. These new cells replace the setting at a wonky angle or not setting at all.
bone, but they all mend in a similar way. callus, returning the bone to its original shape. It will generally be made from plaster of Paris.
This is a mixture of water and gypsum that sets
As a bone breaks, the blood vessels are also Much like repairing a broken toy with glue, really hard once it has dried. The broken bone is
severed. Blood leaks out and forms a clot called the bone needs to be kept straight and steady bandaged and the wet mixture is applied to the
a fracture haematoma. This stops blood flow to for the fusion to happen correctly. This is why gauze. Once it has dried then it should provide
safety and st ability for the bone.
the area and also helps keep both pieces of bone doctors will put a cast on the broken bone. The Fibreglass is an increasingly common cast
aligned, ready for healing. cast provides essential support, protection and material. As with the plaster cast , the broken
The body then makes fibrous cells and stability, ensuring the broken bone doesn't bone is bandaged up. Next, another bandage,
made of f ibreglass and layered with resin, is
cartilage, which reinforce the bond and move. A cast will generally stay on for a few soaked in water. This makes it f lexible enough to
strengthen it. This creates a callus, which is weeks until the bond has become strong be wrapped around the bone before it hardens as
essentially a weakened bone. Over time, the enough, but it could take months for a properly it dries. This is much lighter than a plaster cast
and the outer layer is waterproof.
callus builds up and the two parts of the bone set bone to fully recover.

The stages of bone repair

1-+ollt-'-IF+- New Healed

Blood -..,Jttri'l:-i~ blood
clot fracture
vessels
forms Internal callus --1
(fibrous tissue
and cartilage)

Hard --4+.
bone
Ruptured callus
blood
vessels
External Blood flow
callus improves

Blood clot Tissue growth Remodelling

When a bone breaks, the blood vessels Afew days later, the blood clot- called the fracture Bone-forming cells called osteoblastswork in
that run through the bone are severed. haematoma - is gradually replaced by tougher teams to build a new bone, creatlng a more solid
The blood forms a clot to align the bones. tissue, which becomes a soft callus. Fibrous tissue structure called a hard bone callus. It takes several
This creates a solid yet weak structure to and cartilage are produced that begin to bridge the months to fill the cavity with harder bone,
prepare for mending. The clot also cuts off gap between the fractured ends. New blood vessels strengthened by nutrients like calcium and
blood Dow to the edges of the broken bone, begin to form and the callus usually lasts around phosphorus. However, it may take longer for the
so these cells die. three weeks. bone to be completely healed.

no
 •• • • ••
•• •
•• PI'OteWI we need •
Polu!mon : Biuret test Genome studies
• PloteW. from food
STOP 1Speedy Pd<emon character ;2 We get protein from meat,
•
; 3 Yourbodymakesdlousands • 4 TheBiurettestlsachemical .5
•
From studies into the hutnan

FACTS
Pikachu had a protein named : fiSh, eggs, l'<ltSand dairy • of proteins every day. For each : form of analysis that is used to • genornes sequenced so far, it
after it in 2008. The protein, •• products. We digest the •• !kg you weigh, you typicaDy •
• measure the amount of
••• has been discovered that the
pikachurin, is used in kinetic • proteins Into amino acids, • require lg of protein. So daity a : protein that Is present in food. body contains over' 2 million
• which ......e later use to J"eplace • •
vision, which, aptly, is the •• •• 70kg man must manufacture •
•
It wori<s out protein levels by
•
proteins, coded by just
PROTEIN detection of fast objects. • these proteins in our bodies. • 70g of protein for his needs. • analysing the peptide bonds. • 20,000·25,000 genes.

!•U•Jtl•l!l!tj~l•mG' Around half of your body's 'non-water' moss is mode up of proteins

nus is the 'pn)leiJHTlaking

machfle' nthecel! It uses

Why are
amino acids
important?
Amino acids are vital to
our bodies being able to
operate as they are the
bulldlng blocks of
This IS the control centre of
the ced where all important
proteins. Each type of
genetic data JS stored amino acid performs a
different job, which aids
protein activity in the

How do we make protein? body and determines the

protein's primary
function(s). Without these,
proteins would not be
Proteins are the building blocks of the human body, able to help the body with
but how do we go about manufacturing them? movement, defence
against disease,
Proteins are large complex molecules made up of a and T}and these short sequences, which are known as triplets processing food or
chain of amino acids. Every cell in our body needs or codons, then code mRNA templates; these templates are co-ordinating general
protein to stay alive as it is necessary for tissue 'translated' by cell ribosomes into amino acids. growth and development.
repair and replacing dead cells. Each protein is made up of hundreds of thousands of amino There are nine
They have many other functions as well as aidlng cell repair acids, which are in long chains. There are 20 different types of essential amino acids for
and production including forming antibodies to help fight off amino acid that can be combined to build a protein and it is the humansthatmustbe
disease, forming enzymes which speed up or trigger chemical sequence of amino acids that determines each protein's unique absorbed from external
reactions and co-ordinating processes within the body (via three-dimensional structure and its function. protein sources (eg meat/
hormone regulation, for instance}. Proteins also provide However, notal! amino acids can be made by the body. The fish) as they cannot be
support for cells and form structural elements of the body, such ones that need to be consumed via our diet are called essential synthesised by the body.
as nails and teeth, as well as facilitating the transportation of amino acids. If possible, the body will also conserve energy by Without the required
some small molecules around various systems. using amino acids from food rather than producing them itself. amount of amino acids,
We build proteins using information encoded in our genetic Protein deficiency can cause diseases such as kwashiorkor, a the body can really suffer.
code. DNA code utilises groups of three letters (a mix ofA, G, C form of malnutrition common in poverty-stricken areas.

111
 =··
Cell division explained
 Answer:
What is a optosis? Essentially a cell committing suicide. apoptosis is a
conltOied biological system that kills off ooneeded
Ot excess celts. One example is the retn011al of

APPETITE FOR SElF.· A Another type of cell division B Programmed webbing in between )'OU" fonge<s and toes before

DESTRUCTION eel death c-A new type of soft drink )'OU are botn.

I•U•Jtl•IYt3~1•1@ A common theory 1s that every living cell is descended from a single ancestral cell from 3-4bn years ago

An expert's view
Paul NU"se, Nobel PI ize Willolel' and diredor of the Francis Crick Institute, chats
about cell cycle
What is the cell cycle?
The cell is the basic unit of life for all living things. Why do skin cells divide so quickly and nerve
One of its many properties is the ability to reproduce. cells so slowly?
The cell cycle is a series of processes that occur Cells change at varying rates and some nerve cells
between the birth of the cell and its division into two. barely divide at all. This is one reason why it is
difficult to regenerate the nervous system when it
What is mitosis? becomes damaged. Because the body has to deal
M itosis describes what happens near the end of the with cuts and abrasions, it is much easier to get skin
cycle. The replicated chromosomes are separated cells to divide.
from each other into opposite ends of the cell just
before t he cell divides. What is tissue culture and why is it important?
It Is simply a way of growing cells from animals and
What are the different parts of the cycle? plants in t est tubes. They will divide under these
The other major part occurs before m itosis and is the c ircumstances so you can study the cell cycle away
process in which the DNA that makes up the from the complexities of an animal or plant
chromosomes replicates itself. This is called the
S·phase or DNA synthetic phase [which is part of What are the differences between plant and
interphase]. The S·phase replicates and mitosis anim al cell cycles?
separates and divides. Fundamentally, not very much. They both undergo
the same processes but are subject to different
What is the difference between mitosi.s and overall controls.
meiosis and does cell division occur in both?
Meiosis is usually considered to be the mitotic futl What is proteolysis and how does that
cycle and also leads towards cell reproduction. mechanism help the cell cycle?
However, in meiosis there are two M·phases or It is a biochemical mechanism that breaks down
divisions so the number of DNA and chromosomes protein. It takes away certain proteins as part of a
are halved. Meiosis uses gametes for fertilisation in regulatory system for a variety of biological process
diploid cells in animal and plants. such as the ceU cycle. It is used at the end of the
cycle to destroy excess protein and prepare for the
Does it occur in eukaryotic or prokaryotic cells? next cycle.
Only in euk.aryotic cells. In prokaryotic cells there is a
cell cycle but it is not mitosis. This [procesS] is You discovered CDK (Cyclin-dependent kinase).
simply the copying of DNA and then a much less How do they contribute to the cell cycle?
obvious separation of the copied DNA into the two CDK is a type of enzyme and my research group was
divided cells. involved in discovering that they were the major
regulators in the cycle. CDK brings about the S·phase
Why did you use yeast in your experiments? and mitosis and controls them.
Yeast is a very simple eukaryote, which reproduces
in much the same way as more complex cells in us. It How can the cycle help understand potential
only has 5,000 genes compared to our 25,000. It cures for cancer?
simplifies cell div ision so is extremely convenient to To understand cancer, you have to be able to
study. It 's got fantast ic genet ics and genomics, understand the cell cycle. Crudely blocking t he cell
which allow you to invest igate complicated cycle is a problem as a therapy as our body is full of
processes like t he cell cycle. other cells that have to divide.

• •
•
•
•• •

Paul Nurse is also the

former director of Cancer
Research UK and president
of the Royal Society
 =··
load cells explained

Monocyte

ite Monocytes help prepare us

for another infection by
presenting pathogens to the
body, so that antibodies can
be created. later in their life,

ce • wo rnonocytes rno~~e from the

bloodstream into tissue,
and then ~Ill<! into
macrophages which can
One of the body's main defences against infection and conduct phagocytosi.s.

pathogens, how do these cells protect our bodies?

White blood cells, or leukocytes, are
the body's primary form of defence Types of leukocyte
against disease. When the body Is Different kinds of WBC have different roles, which
invaded by a pathogen of any kind, the complement one another to defend the body
white blood cells attack in a variety of ways; some
produce antibodies, whi le others surround and
ultimately devour the pathogens whole.
In total, there are live types of white blood cell
tWBC), and each cell works In a dHrerent way to
light a variety of threats. These live cells s it In two
groupings: the granulocytes and the
agranulocytes. The groups are determined based
on whether a cell has ·granules' In the cytoplasm.
These granules are digestive enzymes that help
break down pathogens. Neutrophlls, eosl nophlls
and basophilsare all granulocytes, the enzymes
in which also give them a distinct colouratlon
which the agranulocytes do not have.
As the most common WBC, neutrophlls make up
between 55 and 70 per cent of the white blood cells
in a normal healthy Individual, with the other four
types teosinophils, basophils, monocytes and
lymphocytes) making up the rest. Neutrophlls are •
the primary responders to Infectlon, actively
moVing to the site of infection following a call from
mast cells after a pathogen Is Initially discovered.
They consume bacteria and fungus that has
broken through the body's barriers In a process
called phagocytosis.
Lymphocytes- the second-most common kind
I
of leukocyte- possess three types of defence cells: Lymphocyte
Bcells, T cells and natura ll<l ller cells. B ce lls These release antibodies
release antibodies and activate T cells, while T as well as attack virus and
cells attack diseases such as viruses and tumours tumour cells through three
when directed, and regulatoryT cells ensure the differing types of cell. As a
immune system returns to normal after a n attack. group, they are some of
the longest li~~ed of the
Natural killer cells, mea nwhlle, a ld T cell response
white blood cells with the
by also attacking virus-infected a nd tumour cells, memory cells surviving for
which lack a marker known as MHC. years to allow the body to
The remaining types ofleukocyte release defend itself if repeat
chemicals such as histamine, preparing the body attacks occur.
for future infection, as well as attacking other
causes of illness like parasites.

"Natural k1ller cells Eosinophil

Eosinophils are the white

aid T cell response blood cells that primarily

deal with parasitic

by also attacking infections. They also hall<!

a role in allergic reactions.

VIrus-infected and They make up a fairly small

percentage of the total
tumour cells" white blood cells in our
body - about 2.3 per cent.

114
 t•U•Jtl•I!J001•1t;l0 W8Cs have colour but appear white when blood is put through a centrrfuge, hence their group name

Basophil
Basophils are involved in
allergic response via
releasing histamine and
heparin into the
bloodstream. Their
functions are not fully
known and they only
account for 0.4 per cent of
the body's white blood
cells. Their granules
appear blue when viewed
under a microscope.

A faulty immune system

Neutrophil If the immune system stops working We can often treat these conditions with
Neuttophils are the most property, we are at risk of becoming ill. immunosuppressants, which deactivate
common of the leukocytes. However, another problem is if the immune elements of the immune system to stop the
They have a short life span system actually goes into overdrive and body attacking itself. However, there are
so need to be constantly starts attacking the individual's cells, drawbacks with this treatment as, if the
produced by the bone mistaking them for pathogens. There are a person exposes themselves to another
marrow. Their granules large number of autoimmune ailments seen pathogen, they would not have the normal
appear pink and the cell across the world, such as Crohn's disease, white blood cell response. Consequently,
has multi-lobed nuclei psoriasis, lupus and some cases of arthritis, the individual is less likely to be able to fight
which make them easily as well as a large number of diseases that normally low-risk infections and, depending
differentiated from other are suspected to have autoimmune roots. on the pathogen, they can even be fatal.
types of white blood cell.

115
 science of genetics

116
 THE LONGEST GENOME
An ordinary-looking white flower, Paris japonica, has the
longest known genome with 150 billion base pairs. II
stretched out it would measure over 91 metres (300 feet)!

!•Jf•J\t!I!ll;W•1~W If oll46 human chromosomes were stitched together and stretched they would measure nearly 2m [6.6ft]

Genes define who we are. They are

the basic unit of heredity, each How is our genetic code stored?
containing a coded set of Genetic information is coded into DNA using just four nucleobases: A, C, G and T
instructions to make a protein.
Humans have an estimated 20,500 genes, Chromosome
varying in length from a few hundred to more Humans have 46
chromosomes - 23 pairs
than 2 million base pairs. They affect all containing around
aspects of our physiology, providing the code 20,500 genes.
that determines our physical appearance, the
biochemical reactions that occur inside our
cells and even, many argue, our personalities.
Every individual has two copies of every gene
-one inherited from each parent. Within the
population there are several alleles of each
gene - that is, different forms of the same code, 7'--- Nucleus
with a number of minor alterations in the Surrounded by a double-
sequence. These alleles perform the same thid<ness membrane, the
nucleus contains the genetic
underlying function, but it is the subtle Double stranded - - - - - - . information of the cen.
differences that make each of us unique. DNA has two ccmplementary strands
Inside each of our cells (except red blood - one forms a template to make the
other, aJiowing aca.B'ate replication.
cells) is a nucleus, the core which contains our
genetic information: deoxyribonucleic acid Base pairs
(DNA). DNA is a four-letter code made up of The bases of DNA
are always found
bases: adenine (A), guanine (G), cytosine (C) and in pairs: adenine
thymine (T). As molecular biologist Francis pairs with thymine,
Crick once put it, "DNA makes RNA, RNA makes and guanine pairs
with cytosine.
protein and proteins make us." Our genes are
stored in groups of several thousand on 23 pairs
of chromosomes in the nucleus, so when a cell Double helix _ __ _ J
DNA is arranged in a double heix
needs to use one particular gene, it makes a shape, with the bases fomning the
temporary copy of the sequence in the form of ladder·like rungs in the centre.

DNA's chemical structure Nucleotide

We put deoxyribonucleic acid under the microscope DNA is a polymer made up of
building blocks called nucleotides.
I
Phosphate
+
r--
Phosphate groups
link the sugars of
+
adjacent nudeotides
together, forming a
phosphate backbone.

----+- Hydrogen bond

Two bases interact with
eaclh other by hydrogen
boods (weak electrostatic
interactions that hold the
strands of DNA together).

' - - - - - Nucleobase
Sugar Each nucleotide contains a
Each base is attached base, which can be one of four.
to a fwe-carbon sugar adenine (A), thymine (T),
caDed deoxyribose. guanine (G) or cytosine (C).

117
 =··
The science of genetics
ribonucleic acid (RNA). This copy contains all of fully understood, but having the genome Genetic mutations are the source of variation
the information required to make a protein- available to study is making the task of in all organisms. Most genetic mutation occurs
the building blocks of the human body. identifying genetic risl< factors much easier. as the DNA is being copied, when cells prepare
The Human Genome Project aimed to map Interestingly, the Human Genome Project to divide. The molecular machinery responsible
the entire human genome; this map is discovered we have far fewer genes than first for duplicating DNA is prone to errors, and often
effectively a blueprint for making a human. predicted; in fact, only two per cent of our makes mistakes, resulting in changes to the
Using the information hidden within our genome codes for proteins. The remainder of DNA sequence. These can be as simple as
genetic code, scientists have been able to the DNA is known as 'non-coding' and serves accidentally substituting one base for another
identify genes that contribute to various other functions. In many human genes are (egA for G), or can be much larger errors, like
diseases. By logging common genetic variation non-coding regions called introns, and adding or deleting bases. Cells have repair
in the human population, researchers have between genes there is intergenic DNA. One machinery to correct errors as they occur, and
been able to identify overt, Boo disease- proposed function is that these sequences act even to kill the cell if it makes a big mistake, but
associated genes, affecting illnesses ranging as a buffer to protect the important genetic despite this some errors still slip through.
from breast cancer to Alzheimer's. The information from mutation. Other non-coding Throughout your life you will acquire many
underlying genetic influences that affect DNA acts as switches, helping the cell to turn mutations in your cells. Many of these are
complex diseases like heart disease are not yet genes on and off at the right times. completely harmless, either occurring in

The Human Mapping the human genome

How does our genetic makeup compare to that of other creatures?
Genome
Project Zebrafish - - - - - - - - - - - - - - - - . . . . ,
The Human Genome Project, an Divergence between fish and
initiative to map the sequence of mammals occurred very early
the entire human genetic code, in evolution, so similarities in
began in 1990 and was completed our genes are very
in 2003. The 3.3·billion base pair fragmented.
sequence was broken into
sections of around 150,000 base that we are not
pairs in length and the sequence .,.,~~~:;::;_~ closely related to
for each identified. These were birds, the chicken
then joined and used to map the Human still has regions of
information on to chromosomes This ring represents DNA that are quite
to determine which genes were the genes on a simjlar to ours.
found on each - and in what order. human ctvomosome.
The genome map (right) shows a with the m.rnbe<s
human chromosome compared providing a •
with other animals; the colours representation " ' - - - - Dog
are a 'heat map' demonstrating of scale. Some regions of the
areas where genetic information canine genome are
has been conserved through very different to ours,
evolution (the more fragmented
the pattern, the more differences
'" but the pink bands
show an area that has
there are in the genetic code). been conserved.
.
".~+=;""------ Rat
Chimpanzee -...r The mouse and rat genomes
One of our closest living have sinilar patterns,
relatives - the sotid bands demonstrating these rodents'
demonstrate we share a
close 0110lutionary relationship.
great deal of genetic
infonnation (ie 98 per oent).

Mouse
There is iess in common between
human and mouse (90 per cent),
but we are sufficiently similar that
mice make a good scientific model
for studying human disease.

118
 1865 1905 1953 1983 2003
Grego< Mendel, the father of William Bateson Is the first Francis Click (light) and Polymerase chain reaction Completion of the
I"'''Idem genetics, observes person to use the term James Watson ~I the (PCR) is inll<!nted, enabUng Human Genome Project
patterns of genetic inheritance 'genetics' to de<cribe the stlJdy double helix structure of smal DNA samples to be provides access to the
GENETICS HISTORY in peas grown in his garden. of biological inheritance. DNA using X·rays. amplified for testing. human DNA blueprint.

!•Jf•J\t!I!ll;W•1~W Humans shore 98 per cent genetic similarity with chimpanzees but just seven per cent with E coli

non-coding regions of DNA, or changing the mutant gene, which gave them black wings; A single nucleotide mutation causes
gene so nominally thatthe protein is virtually this made them an easy target for predators and haemoglobin, the protein involved in binding
unaffected. However, some mutations do lead kept their numbers low. When factories began oxygen in red blood cells, to misfold. Instead of
to disease (see 'When genes go wrong' box). to cover the trees in soot, however, the light- forming its proper shape, the haemoglobin
If mutations are introduced into the sperm coloured moths struggled to hide themselves clumps together, causing red blood cells to
a nd egg cells they can be passed on to the next against the newly blackened environment, so deform. They then have trouble fitting through
generation. However, not all mutations are bad, black moths flourished. They survived much narrow capillaries and often become damaged
a nd this process of randomly introduced longer, enabling them to pass on their mutation or destroyed. However, this genetic mutation
changes in the DNA sequence provides the to their offspring and altering the gene pool. persists in the population because it has a
biological underpinning that supports Darwin's It is easy to see how a genetic change like the protective effect against malaria. The malaria
theory of evolution. This is most easily observed one that occurred in the peppered moth could parasite spends part of its life cycle inside red
in anima ls. Take, for example, the peppered give an advantage to a species, but what about blood cells a nd, when sicl<le cells rupture, it
moth. Before the Industrial Revolution the genetic diseases? Even these can work to our prevents the parasite from reproducing.
majority of these moths had white wings, advantage. A good example is sickle cell Individuals with one copy of the sickle cell gene
enabling them to hide against light-coloured anaemia - a genetic disorder that's quite and one copy of the healthy haemoglobin gene
trees and lichens. However, a minority had a common in the African population. have few symptoms of sickle cell anaemia,

Why do we look
like our parents?
Jt's a common misconception that we inherit
entire features from our parents - eg "You have
your father's eyes." Actually inheritance is much
more complicated - several genes work together
to create traits in physical appearance; even eye
colour isn't just down to one gene that codes for
•blue', 'brown' or 'green', etc. The combinations of
genes from both of our parents create a mixture of
their traits. However, there are some examples of
single genes that do dictate an obvious physical
characteristic all on their own. These are known as
Mendelian traits, after the scientist Gregor Mendel
who studied genetic inheritance in peas in the
1800s. One such trait is albinism - the absence of
pigment in the skin, hair and eyes due to a defect
in the protein that makes melanin .

. - - Carrier parents
Each parent carries the
albinism gene (dark pink), but
they have one normal gene
Carrier children - , (li!# pink), so they are able
Two out of four wiR be to make melanin.
carriers, like their parents,
with ooe normal and one
faulty gene.
- - Gametes
Each child inherits one
gene from the mother and
one from the father.

Healthy child
One in four children will Affected child
reoeive ooe healthy gene One in four children wil
from the father and one receive two copies of the
from the mother. faulty gene and as a
result will be unable to
produoe melanin.

119
 =··
science of genetics

but are protected from malaria too, allowing

them to pass the gene on to their children.
Genetics is a complex and rapidly evolving
( Repairing faulty genes
We reveal how donated cells can be used to mend
field and more Information about the function any damaged genes within the human body
of DNA is being discovered all the time. It is now
known that environmental influences can alter Target gene
The healtt1y gene is
the way that DNA is packaged in the cell, Isolated from the DNA
restricting access to some genes and altering of the donor in<ividlal
protein expression patterns. Known as
epigenetics, these modifications do not actually
alter the underlying DNA sequence, but
regulate how it is accessed and used by the cell.
Epigenetic changes can be passed on from one
cell to its offspring, and thus provide an
additional mechanism by which genetic
Packaging
The gene is
packaged into a
delivery vector,
X
like a virus. to
information can be modified across generations h.-, it get inside Fertilised egg
of humans. the target ceiL A furtiised human egg is a
source at l.l1cifferenliated
stem celts, which can
become ant type at cell

' - - Transduction
Embryonic The new gene is irllrodx:ed
stem cells into the stem eels pn:rlx:ed
The furtiiised egg by the lertiised-
be<:a ooes a blastocyst.
wl1ich ax otai os
Ll1<iflerenliat
embryonic stem eels.

When our genes

go wrong...
Cancer is not just the result of one or two genetic
mutations - in fact, it takes a whole series of
mistakes for a tumour to form. Cells contain
oncogenes and tumour supp!'essor genes, whose
healthy function is to tell the cell when it should Differentiation
Chemical signals are
-----1
and should not divide. If these become damaged,
the cell cannot switch off its cell division
programme and it will keep making copies of
itself indefinitely. Each time a cell divides there is
a risk that it will make a mistake when copying its
added to the stem cells to
force them to diffe<entiate
into the desired cell type,
eg Iiiier cells. Transplant
t
DNA, and gradually the cell makes more and more The new cells are transplanted
errors, accumulating mutations that allow the into the recipient, caoTylng with
tumour to progress into malignant cancer. them the healthy gene.

• How tumours develop

Tumour-associated Mutagens l ocalised Invasion Metastasis ..

~
!!
'l!
genes EnWonrnental ~actors. or Cancer usualy slats with just As the tumour grows in Ft.1her mutatiions allow eels
....
L

Genes normally irwoM!d in mutagens- such as raciation one or a few mutated cells; slz.e ~ starts to Invade of the tJ..mour to break free and
regulating cell behaviol.r can and dlemicals- can cause these begin to civide the surounding area. erter the bloodstream. From "'
""..
E

go on to cause cancer ff they damage to the DNA, leading to LI1<Xll'llrollably in !her local taking <MY here they can be distributed :.t
a.
become mutated. mutations in keygmes. il'ea aeating a tumour. neighbouring tissues. thO'OU!I>oot the body. I>

120
!•U•I\1•1!1!tj~l•lmP Approximately 3ao,aoo people die from burns eoch year worldwide

urn ourse •
Burns range from irritating to life-threatening
-learn about the different types now
Most people associate burns with red skin, but without large blisters. Only the no sensation. The basal growth layer is
flames, but they have many other epidermis is damaged, so regrowth is fast. destroyed so no new skin can grow.
causes. Aburn is medically defined Second-degree burns (partial thickness! can be Even minor burns can cause problems if not
as 'coagulative destruction' of skin, either superficial or deep. The skin usually treated properly. The first priority is to stop the
meaning any energy source can cause one. This blisters and can be very painful. The dermis burning process; cold running water is ohen
energy damages underlying skin proteins and layer is also damaged so regrowth is slow, the best first treatment. Infection, dehydration
fat cells, causing breaks in the skin. taking several weeks or even months. In and protein loss are all problems that occur
Burns are generally classified by their depth. third-degree burns (full thickness! the skin is next, which ourresilientskin can solve itself if
First-degree (superficialI burns leave painful, left white or pale, with no blistering and little to the injury isn't too severe.

How bums are measured

Classified by their depth, each bum case requires unique treatment

i (fl;
- .......... /II
'

0The skin ~ First-degree burn 0Btisters

Your skin is vital to your wellbeing. It has multiple Only the uppermost skin layers (known as the epidermis) Blisters appear when the epidermis separates from the
important functions, including temperature control, are affected, but the burn is painful, leaving the area red, dermis, and are especially common in first and
sensation and appearance. raw and tender to the touch. second-degree burns.
f) Basal layer 0 Second-degree burn @Third-degree burn
This layer is the key to regeneration, as new skin cells These partial-thickness burns affect the upper or deep Deep burns destroy the basal layer and nerve ending.s, so
grow from hae. If undamaged, regrowth occurs w ithout dermal layers, and like first-degree burns hurt a lot they are painless. Regrowth will not occur alone, so skin
any need for medical assistance. because the nerve endings remain active. grafts are needed.

. .
burns can be covert he deep bums that lieal

Sunburnlsaconunon
(lmownas wet typeofradlatlon burn,
burns) or contact caused l!Y exposure to
UV.tn suiillghtJ

121
 =··
Blood vessels
Mostoftheamyloid
consisted of acellular pink
globules that effaced and
expanded the node, but
this image shows the
characteristic involvement
ofbloodvesselwalls

Arteries and veins form the plumbing system of the human

body, carrying blood through a complex system of different
sized and shaped pipes. We find out howtheywork ..
The network of blood vessels in the two varieties; oxygen-rich (oxygenated} blood is like small back-roads connecting motorways to
human body must cope with different what the body uses for energy, and is bright red. dual carriageways.
volumes of blood travelling at different After it has been used, this oxygen-depleted Arteries and veins are constructed differently to
pressures. These blood vessels come (deoxygenated} blood is returned for recycling and is cope with the varying pressures, but work in perfect
in a multitude of different sizes and shapes, from dark red (not blue, as is often thought). tandem to ensure that the blood reaches its final
the large, elastic aorta down to very tiny, one-cell- Blood is carried in vessels, of which there are destination correctly. However, sometimes things go
thick capillaries. two main different types - arteries and veins. wrong which can lead to certain medical problems:
Blood is the ultimate multitasker. It carries oxygen Arteries carry blood away from the heart and deal varicose veins from failing valves; deep vein
for various tissues to use, nutrients to provide with high pressures, and so have strong elastic thrombosis from blood clots blocking the deep
energy, removes waste products and even helps you walls. Veins carry blood back towards the heart and venous system; heartattacks from blocked arteries;
warm up or cool down. ltalso carries vital clotting deal with lower pressures, so have thinnerwalls. and lastly life-threatening aneurysms from weak
factors which stop us bleeding. Blood comes in just Tiny capillaries connect arteries and veins together, artery walls.

ConnectiVe Capillary wall

tissue
L Elastic layer ----:~"/ Cell nucleUs _j
Muscle Inner fining
L
Outer
protective
layer
Valve
' - - Muscle layer

How do veins -under Connecting it

work? pressure! all together
Veins carry low pressure blood. They Arteriescopewithall of the pressure Capillaries are the tinyvesselswhich
contain numerous one-way valves which generated by the heart and deliver connect small arteries and veins together.
stop backwards flow of blood, which can oxygen-rich blood to where it needs to be 24 Their walls are only one cell thick, so this Is
occur when pressure falls in-between hours a day. The walls of arteries contain the perfect place to trade substances with
heartbeats. Blood flows through these elastic muscles, allowing them to stretch surrounding tissues. Red blood cells
valves towards the heart but cannot pass and contract to cope with the wide changes within these capillaries trade water,
back through them in the other direction. in pressure generated from the heart. Since oxygen, carbon dioxide, nutrients, waste
Valves can fail over time, especially in the the pressure is high, valves are and even heat Because these vessels are
legs. This leads to saggy, unsightly veins, unnecessary, unlike the low-pressure only one cell wide, the cells have to line up
known as varicose veins. venous system. to pass through.

122
I•U•Jtl•l!l!:W•l!l.U vascular surgeons con bypass blocked arteries using either the patient's own veins or synthetic grafts
Arteries - - - - ,
AD arteries carry blood away
from the heart They carry
oxygenated blood, except
A of two
for the pulmonary arte<y, In human beings, the heart is a double body tissues Ithe systemic drculation}.
whictl carries deoxygenated pump, meaning that there are two sides The right side of the heart pumps
blood to the lungs. to the drculatory system. The left side of deoxygenated blood towards the lungs, so
the heart pumps oxygen and nutrient-rich it can pick up new oxygen molecules to be
blood to the brain, vital organs and other used again (the pulmonary circulation).
Lungs
In the lungs, carbon dioxide Aorta
is expelled fran the body
and is swapped for fresh
The aorta is an artery whictl
carries oxygenated blood to the "Plasma carries all
o the dif erent
oxygen from the air. This body; it is the largest blood
oxygen-rich blood takes on ~~<!Sse! in the body and copes
a bright red colour. with the highest pressure blood.
ypes o cells"

What's in
blood?
It's only the iron in red blood cells which
make blood red- take these cells away and
what you're left with is a watery yellowish
solution called plasma. Plasma carries all
of the different types of cells and also
contains sugars, fats, proteins and salts.
The main cell types are red blood cells
(formed from iron and haemoglobin, which
carries oxygen around the body), white
blood cells (which fight infection from
Veins - - - ' - - - The left side bacteria, viruses and fungi) and platelets
AU veins carry blood The left side of the heart (tiny cell fragments which stop bleeding by
p<.mps oxygenated blood forming dots at the sites of any damage}.
to the heart. They
for the body to use. ~
carry deoxygenated
pumps directly into
blood, except for
arteries towards the brain
the pulmonary vein,
and other body tissues.
which canies
oxygenated blood
back to the heart
Blood vessels
Different shapes and sizes

Capillary sphincter muscles Capillary bed

These tiny musdes can open and close, This is the capillary network that
The ng
- ht which can decrease or increase blood flow connects the two systems. Here,
side - - - through a capillary bed. When musdes exchange of various substances
The right side of the
exercise, these muscles relax and blood occurs with surrounding tis~
heart pumps
flovv into the musde increases. ~- through the one-cell thick walls.
deoxygenated
blood to the lungs,
w here blood
exchanges carbon
dioxide for
fresh oxygen. Venule

Capillaries _ _,
Tiny capiDaries connect
arteries and vejns
together. They aDow
exchange of oxygen, Arteriole
nutrients and waste in the
body's organs and tissues. Vein Artery

123
 A look inside your blood

The science behind the miraculous fluid

that feeds, heals and fights for your life
 .
• •
•• •
•
HEAD~ l.Dis~of 2. First blood 3. Discovery of
•
• •••

HEADt=
veins and arteries • transfusion
ln 300 BC, Gr'eek anatomist
•
• After' a centwy of animal·
Her'ophilus ot Chakedon figured • •
blood types
In 1901, Austtlan physician "1818- first human-to-
• human blood transfusions. Kafllandsteiner was the fitst

LANDMARK out that anerles and veins

not only cany blood. but ate
• James Blundel perfom>ed the
•
• to Identify three basic blood
first r'ecOf'ded t.JmarHo--humao • gr'oups. tevolutionising the
human transfusion"
BlOOD EVI:'MTc: distinct pathways. transfusion in 1818. • success of blood transfusions.

!•U•I\1•1!1!tj~l•lmP If you took oil of the blood vessels out of your body and laid them end to end, they would stretch for 16o,oookm

Monocyte
The largest type of white blood cell, monocytes are born in bone
marrow, then tirculate through the blood stream before maturing
into macrophages. predatory immllle system cells that live in
organ tissue and bone.

Blood is a mix ofsolids and liquids, a blend of highly specialised

cells and particles suspended in a protein-rich fluid called
plasma. Red blood cells dominate the mix, carrying oxygen to
Jiving tissue and returning carbon dioxide to the lungs. for
every 6oo red blood cells, there is a single white blood cell, of
which there are five different kinds. Cell fragments called
platelets use their irregular surface to cling to vessel walls and
initiate the clotting process.

54%
Plasma

Bone marrow contributes

four per cent ofa person's
total weight

j
J.
~
"Red blood cells ore so numerous
because they perform the most
essential runction of blood"
Blood is the river oflife. It watery current of plasma- a straw- deliver oxygen to every cell in the blood cells only live 120 days, the
feeds oxygen and coloured, protein-rich fluid - carrying body and carry away carbon dioxide. supply must be continuously
essential nutrients to billions of microscopic solids As an adult, all of your red blood cells replenished; roughly 2 million red
living cells and carries consisting of red blood cells, white are produced in red bone marrow, the blood cells are born every second.
1wa1y Vllaste.lt transports the foot blood cells and cell fragments called spongy tissue in the bulbous ends of Amature red blood cell has no
soldiers of the immune system, white platelets. The distribution is far from long bones and at the centre of flat nucleus. The nucleus is spit out during
blood cells, which seek out and equal. Over half of blood is plasma, bones like hips and ribs.ln the the final stages of the cell's two-day
destroy invading bacteria and 45 per cent is red blood cells and a marrow, red blood cellsstartoutas development before taldng on the
parasites. And it speeds platelets to tiny fragment, Jess than one per cent, undifferentiated stem cells called shape of a concave, doughnut-like
the site ofinjury or tissue damage, is composed of white blood cells hemocytoblasts.Jf the body detects a disc. Like all cells, red blood cells are
triggering the body's miraculous and platelets. minuscule drop in ox:ygen carrying mostly water, but 97 per cent of their
process ofself-repair. Red blood cells are so numerous capacity, a hormone is released from sol!d matter is haemoglobin, a
Blood looks l!ke a thick, because they perform the most the kidneys that triggers the stem cells complex protein that carries four
homogenous fluid, but it's more like a essential function of blood, which is to to become red blood cells. Because red atoms ofiron. Those Iron atoms have

125
 =··
A look inside your blood
Waste product 6. Reuse and recycle . . - - - - L Born in the bones 2. One life to live
As for the globin and other cellular When the body detects a low oxygen Mature red blood oells,
of blood cell carrying capacity, honnones released from
membranes, everything is atso known as
converted back into basic amino the kidney trigger the production of new erythrocytes, are
acids, sane of which wil be used red blood cells inside red bone marrow. stripped of their nucleus
to create more red blood oells. in the final stages of
dev<>lopment, meaning
they can\ cfl\lide
to replicate.

Life cycle of
cells
Waste
excreted
from body
Every second, roughly 2 million red blood cells decay and die.The
body is keenly sensitive to blood hypoxia - reduced oxygen
carrying capacity-and triggers the kidney to release a hormone
called erythropoietin. The hormone stimulates the production of
more red blood cells in bone marrow. Red blood cells enter the
bloodstream and drculate for 120 days before they begin to
degenerate and are swallowed up by roving macrophages in the
liver, spleen and lymph nodes. The macrophages extract Iron from
the haemoglobin in the red blood cells and release it back into the
bloodstream, where It binds to a protein that carries it back to the
bone marrow, ready to be recycled in fresh red blood cells.

5. Iron ions ------J

In the belly of Kupffer cells,
haemoglobin molecules are split into
heme and globin. Heme is broken
down further into bi~ and iron ions,
some of which are carried back and
stored in bone marrow.

4.1ngestion - - - - - - - - - - 3. In circulation
Specialised white blood cells in the iver and Red blood cells pass from
spleen called Kupffer eels prey on dying red blood the bone marrow into the
eels, ingesting them w hole and breaking them bloodstream, where they
down into reusable components. circulate for around 120 days.

the ability to form loose, reversible red blood cells release their oxygen, another type of white blood cell, proteins and clotting factors found in
bonds with both oxygen and carbon they pick up carbon dioxide produce anti-bodies that build up our plasma, platelets weave a mesh of
dioxide - think of them as weak molecules, then course through the immunity to repeat intruders. And fibrin that stems blood loss and
magnets - making red blood cells such veins back toward the heart, where monocytes, the largest of the white triggers the formation of new collagen
an effective transport system for they are pumped back into the lungs blood cells, enter organ tissue and and skin cells.
respiratory gasses. Haemoglobin, to 'exhale' the excess co, and collect become macrophages, microbes that But even these three functions of
which turns bright red when some more precious 0 ,. ingest bad bacteria and help break blood- oxygen supplier, immune
oxygenated, Is what gives blood its White blood cells are greatly down dead red blood cells Into system defender and wound healer -
characteristic colour. outnumbered by red blood cells, but reusable parts. only begin to scratch the surface of the
To provide oxygen to every living they are critical to the function of the Platelets aren't cells at all, but critical role of blood In each and every
cell, red blood cells must be pumped immune system. Most white blood fragments of much larger stem cells bodily process. When blood circulates
through the body'scirculatorysystem. cells are also produced in red bone found in bone marrow. in theirresting through the small intestine, it absorbs
The right side of the heart pumps marrow, but white blood cells- unlike state, they look like smooth oval sugars from digested food, which are
CO,-heavy blood into the lungs, where red blood cells- come in five different plates, but when activated to form a transported to the liverto be stored as
it releases its waste gasses and picks varieties, each with its own clot they take on an irregular form energy. When blood passes through
up oxygen. The left side of the heart specialised immune function. The with many protruding arms called the kidneys, it is scrubbed of excess
then pumps the freshly oxygenated first three varieties, collectively called pseudopods. This shape helps them urea and salts, waste that will leave
blood out into the bodythrougha granulocytes, engulf and digest stick to blood vessel walls and to each the body as urine. The proteins
system of arteries and capillaries, bacteria and parasites, and play a role other, forming a physical barrier transport vitamins, hormones,
some as narrow as a single cell. As the in allergic reactions. Lymphocytes, around wound sites. With the help of enzymes, sugar and electrolytes.

126
 Sr~~~v~~f~fGE 7°/o ~~<A~9 p~~~ sv 7,000 litres
~\:R~£>~~oov 5 litreS ~£>o~~$~~5oND 2 million
l•lf•Jtl•I!JOOI•lt;lQ until the 23rd week of foetal development, red blood cells ore produced in the liver, not red bone morrow

"lia lbalassentJa
lbls rare genetic blood dlsordersewrely lnhlblls the Another rare blood disorder alfectlngtoo,ooo
cloU1ng mecbanlsm of blood. causlngexteS11lw newborns worldwide each year,lbalassemla
bleeding. Internal bruls1Jl8and joint problems. Platelels Inhibits the prodliCfioo of haemoglobin. leading
are essential to the clott1Jl8and heallng process. tose~~ereanaemla People who are bomwtth the
producing threads of fibrin with help from proteins In most senous form of the disease. also caUed
thebloodstreamcalledclotUnglactors.~plewho Cooley'sanaemla,suHetlromenlalgedbeans,
suHet from baemophllla -almost exclusively males-are Uwrsandspleens,and brlnJe bones. Tbe most
mlsslng one oftboseclolt1Jl8 facoors. maldng udlfflrultto effectllle treatment Is frequent blood
seal oU blood vessels alter even minor inJuries. transfuslons_allhougha few Juckypatlents baw
been cured through bone marrow transplants
from perfectly matching donors.

One of the most common geneUc

blood disorders, hemochromatosis Is
the medical term for"lron overload;
Sickle cell anaemia In which your bodyabsorbsand
Anaemia Is the name for any blood dlsorderthat results stores too much Iron from food
In a dangerously low red blood eel I count. in sickle cell Severity varies wildly,
anaemia, whlchaffllctsoneout of every6z5 children of and many people experience few
African descent, red blood cells elongate Into a sickle symptoms, but others suffer
shape alter releasing thelr oxygen. The slclde-shaped serious liver damage or
cells die prematurely, leading to anaemia, or some<lmes scarrlngjclrrhosls~ Irregular
lodge In blood vessels, causing terrible pal nand ellen heanbea~ diabetes and even heart
organdarnage.lntetestlngly, people who carry only one failure. Symptoms can be aggravated
gene for sickle cell anaemia are Immune to malaria. bytaldngtoomuchv!tamlnC.

Deep vein
Thrombosis Is the medical term for any blood clot that Is
large enough to blocl< a blood vessel. When a blood dol
forms in the large. deep veins of the upperthlgb.lt's
called deep vein thrombosis. IIsuch a dot breaks free. it
can circulate through the bloodstream, pass through
the bean and become lodged lnanetles In the lung.
causlngapulmonaryembollsm.Suchablockagecan
severely damage ponlonsof the lungs, and multiple
embolisms can even be fataL

Think of blood as the body's

hea More than a one-trick pony, your blood
is a vital cog in the hea1ing process
emergency response team to an STAGE! STAGE4
injury. Platelets emlt signals that
encourage blood vessels to
contract.stemmlngbloodloss.
The platelets then collect around . "-'
the wound, reacting with a
protein in plasma to form fibrin, a
tissue that weaves lnioa mesh.
Blood Dow returns and white
blood cells begin their hunt for
bacteria fibroblasts create beds INJURY HAEMOSTASIS INFLAMMATORY STAGE PROLIFERA11VE STAGE
of fresh collagen and caplllarles When the sidn surface is CUI, tom Activated plateletsaggresate Once the wound Is capped with a Fibroblasts lay lresb layers of
to fuel skin cell growth. The scab or soaped deeply enough. blood around the surface ollbewound, drytngcloc. blood vessels open up collagen lnsldelbewoundand
seeps from broken blood vessels to stim1•Jat1ngvasoconst:rictln. again, releasing plasma and white caplllaries begin to supply blood
begins to contract, pulling the Plateletsreactwttha protein In blood cells Into the damaged for lbe forming of newsldncells.
1111 thewound. To stem the flow of
growing skin cells closer together bleeding. the blood vessels around plasma to form fibrin, a web-like Ussue.Macrophagesdlgest Fibrin strands and collagen pull
until damaged tissue Is replaced. the wound const:rl~ mesh of strtngyllssue. harmful bacteria and dead cells. the sides of the wound together.

127
 Controlling the human body

Hypothalamus
Releases honnones to the
pituitary gland to promote
as production and
seoetiorl d honnones to
the rest al the body.

How the human endocrine system

develops and controls the human body
The glands in the endocrine system women. The majority of hormones are peptides Pituitary gland
use chemlcais called hormones to that consist of short chains of amino acids. Releases honnones to
communicate with and control the They are secreted by the pituitary and the male and female
pa rathyrold glands. Amine hormones are repro<Nctlve organs
cells and organs In our bodies.
and to the adrenal
They are ductless glands that secrete different secreted by the thyroid and adrenal medulla glands. Stimolates
types of hormone directly Into the bloodstream and are related to the fight or flight response. growth In childhood and
and target specific organs. The changes that are caused by the maintains adult bone
The target organs contain hormone endocrine system act more slowly than the and muscle mass.
receptors that respond to the chemical nervous system as they regulate growth,
tnstructlons supplied by the hormone. There moods, metabolism, reproductive processes
are 50 different types of hormone In the body and a relatively constant stable internal
and they consist of three basic types: peptides, environment for the body (homeostasis). The
Pineal gland
ami nes and steroids. pituitary, thyroid and adrenal glands combine Secretes melatonin. wt-ich
Steroids include the testosterone hormone. to form the major elements of the body's 00<1bols s!Hp patterns and
This is secreted by the cortex of the adrenal endocrine system along with various other 00<1bols the production of
gland, the male and female reproductive elements such as the male testes, the female honnones related to the
organs and by the placenta in pregnant ovaries and the pancreas. ~organs.

"Amine hormones ore secreted by the

thyroid and adrenal medulla"

gla endocrine
We have two adrenal glands that are positioned on top of both
kidneys. The triangular-shaped glands each consist of a two-
system
centimetre thick outer cortex that produces steroid hormones,
which include testosterone, cortisol and aldosterone. Thymus
The ellipsoid shaped, Inner part of the gland Is known as the Is part of the invnune
system. It produces
medulla, which produces noradrenaline and adrenaline. These
thymosins that control
hormones increase the heart rate, and the body's levels of oxygen the behaviour of white
and glucose while reducing non-essential body functions.
The adrenal gland Is known as the 'fight or Oight' gland as It
blood T·cells. J
controls bow we respond to stressful situations, and prepares the
j
body for the demands of either fighting or running away as fast as Adrenal glands
Cattro!s the burning of
you can. Prolonged stress over-loads this gland and causes illness. protein and fat, and
regulates blood.,...,......,.
MecUia The medulla secretes
adrenaline to strnulate the
Cortex fight or fl91t response.

Kidney

Male testes
Tbesel'INOglandsproduce
testosterone that Is
responsible lorsperm
production, muscle and
bone mass and sex drive.

128
l•U•l\1•lfll!W•Itf.t? When you ore exdted the hypothalamus and pituitary gland release opiate-like endorphins

Hypothalamus
Hypothalamus ----...:
neurons
These synthesise and
'-- ' itaryg
The pea-sized pituitary gland is a major production of sperm cells. The posterior
send honnooes to the endocrine gland that works under the lobe stores vasopressin and oxytocin that
posterior lobe. control of the hypothalamus. The two is supplied by the hypothalamus.
organs inside the brain work in concert and Vasopressin allows the retention ofwater in
Portal veins mediate feedback loops in the endocrine the kidneys and suppresses the need to
Honnones from the system to maintain control and stability excrete urine.It also raises blood pressure
hypothalamus are
within the body. by contracting the blood vessels in the heart
carried to the
anterior lobe
The pituitary gland features an anterior and lungs.
through these veins. (front) lobe and a posterior (rear) lobe. The Oxytodn influences the dilation of the
anterior lobe secretes growth hormones cervix before giving birth and the
Anterior lobe that stimulate the development of the contraction of the uterus after birth. The
muscles and bones; it also stimulates the lactation of the mammary glands are
development of ovarian follicles in the stimulated by oxytocin when mothers begin
Posterior lobe female ovary. In males, it stimulates the to breastfeed.

Parathyroid
Wcxl<s in combination
with the thyroid to
Thyroid and
Thyroid cartilage
control lewis of calcium.
The two lobes of the thyroid sit on each side of the
r - - - (Adam's apple) windpipe and are linked together by the isthmus that
runs in front of the windpipe. It stimulates the amount
ofbodyoxygenand energy consumption, thereby
Thyroid keeping the metabolic rate of the body at the current
Important fur maintaining levels to keep you healthy and active.
the metabolism of the . .. The hypotha lamus and theanteriorpituitarygland
body. It releases n and are in overall control of the thyroid and they respond to
T4 honmones to control
the breakdown of food
changes in the body by either suppressing or Increasing
Right thyroid stimulating hormones. Overactive thyroids
and store it, or release it
as energy.
lobe cause excessive sweating, weight loss and sensitiVity to
heat, whereas underactive thyroids cause sensitivity to
Left hot and cold, baldness and weight gain. The thyroid can
lobe - swell during puberty and pregnancy or due to Viral
infections or lack of iodine in a person's diet.
The four small parathyroids regulate the calcium
Isthmus Trachea _ .,. levels in the body; it releases hormones when calcium
(windpipe) levels are low. Ifthe level of calcium is too high the
thyroid releases calcitonin to reduce it. Therefore, the
Parathyroids -lO..,~- ""' thyroid and parathyroids work in tandem.

Pancreas
Maintains healthy Islets of Red blood Acinar cells
blood s ugar lewis in Langerhans cells These secrete
the blood stream. digestive enzymes
The pancreas is positioned in the abdominal caVity above the small ~-- tothelntestlne.
Intestine. It consists of two types of cell, the exocrine cells that do not
secrete their output into the bloodstream but the endocrine cells do. •• • • •
The endocrine cells are contained in clusters called the islets of
Langerhans. They number approximatelyt million cells and •
are only one or two per cent of the total number of cells in •
the pancreas. There are four types of endocrine cells in
the pancreas. The beta cells secrete insulin and the ......()
alpha cells secrete glucagon, both of which ~
Female ovaries stimulate the production ofbloodsugar (glucose} N-..//11
Are stimulated by in the body. If the Beta cells die or are destroyed
hormones from the
pituitary gland and
it causes type t diabetes, which is fatal unless
control the
treated with Insulin Injections.
menstrual cycle. The other two cells are the gamma and
delta cells. The former reduces appetite
and the latter reduces the absorption of food
in the intestine.

129
 =··

Kidneys
This is where liquids are

•
fi~ered and nutrients are
absorbed before urine
exits into the ureters.

Every day the body J?roduces waste

products that enter the bloodstream-
but how do we get rid of them?
The human urinary system's water levels in the body, sodium and Ureter
primary function Is to remove potassium levels among other electrolytes, These tubes link the
by-products which remain In blood pressure, pH of the blood and are kmeys and the bladde<".
the blood after the body has also involved in red blood cell production
metabolised food. The process Is made up through the creation and release of the Inferior vena cava
of several different key features. Generally, hormone erythropoietin. Consequently, TNs carries deoocygenated
this system consists of two k1dneys, two they are absolutely crucial to optimum blood back from the 1<meys
ureters, the bladder, two sphincter body operation. 1D the rig>~ aorta ol the heart.
muscles (one internal, one external) and a After blood has been filtered by the
urethra and these work alongside the k1dneys, the waste products then travel Abdominal aorta
intestines, lungs and skin, all of which down the ureters to the bladder. The This artery 5l4llllies blood
excrete waste products from the body. bladder's walls expand out to hold the 1D the kic*leys, w the renal
The abdominal aorta !san Important urine until the body can excrete the waste artery and vein This blood
artery to the system a s this feeds the renal out through the urethra The internal and is then cleansed 1)11
the kic*leys,
artery and vein, which supply the kidneys external sphincters then control the
with blood. This blood is filtered by the release of urine.
kidneys to remove waste products, such as Generally, a human will produce
urea which is formed through amino acid approx1matelyz.s<J litres of urine a day, Bladder
metabolism. Through communication a !though this can vary dramatically This is where urine
with other areas of the body, such as the dependant on external factors such as gathers after being
hypothalamus, the kidneys also control water consumption. pass«! down the
ureters from
the kidneys.

"Generally, a human will produce

2.5-3/itres of urine a day"

How do the kidneys work?

The kidneys will have around 15o-t8o lltresofblood to filter per day, butonlypassaround
two lines of waste down the ureters to the bladder for excretion, therefore the kidneys
return much of this blood, minus most of the waste products, to the heart for re-
oxygenationand reclrculaUon around the body.
Thewaythekidneysdothlsls to pass the blood through a small filtering unit called a
nephron. Each kldneyhasarounda million of these, which are made up ofa number of
small blood capillaries and a tube ca lied the renal tubule. The blood capillaries sift the
normal cells and proteins from the blood for recirculation and then direct the waste
products into the rena I tubule. ThIs waste, wh lch will primarily consist of urea, mixes with
water and forms urine as it passes through the renal tubule and then into the ureter on its
way to the bladder.

130
I•UaJW•IIlt:W•WlP On overage, you make the some amount of unne in the day as in the night

(How do store~ until

we're ready to expel it?
The bladder stores waste produCts by allowing the urine to enter
through the uretervalves, which attach the ureter to the bladder.
The walls relax as urine enters and this allows the bladder to
stretch. When the bladder becomes full, the nerves In the bladder
communicate with the brain and cause the Individual to feel the
urge to urinate. The Internal and external sphincters will then
relax, allowing urine to pass down the urethra.

1. Ureters
Bladder These tubes connect to t he kidneys and urine
flows down to the bladder through them.

Why do we 2. Internal urethral sphincter

This remains dosed to ensure urile does
get thirsty? not escape unexiJ"Ctedly.

Malntalnlng the balance between the I

minerals and salts in our body and water is
very Important. When this is out of balance,
the body tells us to consume more liquids to
redress this Imbalance In order for the body
to continue operating effectively.
This craving. or thirst can be caused by 3. Extemal
too high a concentration of salts In the body, U'ethral
or by the water volume In the body dropping sphincter
too low for opti rna I operation. Avoiding TNs secondary
dehydration is Important as long term

G
spiWlcter also
dehydration can cause renal failure, among remains dosed
other conditions. to ensure no
o.aine escapes.
5. Bladder walls
(controlled by
4. Ureter valves detrusor muscles)
These..,_ an! situated

Tbe
The detrusor rnJSdes in thewaU of
at the end of the ureters the IJjadder relax to allow expansion
and let urine in. of the bladder as neoessary.
•
un Bladder L Internal urethral sphincter

system empties
This relaxes when the body is reacly to expel

2.Extemal
the waste.

Renal artery and vein urethral sphincter

This also relaxes for the OOne
This supplies blood to the kidneys
to exit the body.
in order for them to operate, and
then renlOIII!S deoxygenated bjood
after use by the kidneys.

~--------------- ~
The IJjadder sits in the pelvis,
and the urethra passes t!vough
it for o.aine to exit the body.

3. Bladder
walls
-
---~- :1-- - - - - - - Urethra
The t.n!!lva is the b.i>e (controled
that ..me travels by detrusor
t!vough to exit the body. muscles)
These muscles
""'ob act to Ioree

!
~
0
the o.aine out ol
thebjadder.
Urine travels down tns
passageway to exit the body/
Q

131
 =··

rae eoto
Discover the science and tech behind this life-saving procedure
Lf the upper airway is blocked, by
trauma, cancer or inflammation, an
Anatomy of a tracheotomy
The trachea is surrounded by a minefield of major
alternative route must be found for blood vessels, nerves, glands and muscles
air to enter the lungs.
Planned tracheotomies are performed under
general anaesthesia or sedation. The neck is
extended backwards to a llow the surgeon to
easily identify the structures In the throat and Thyroid cartilage
The surgeon uses the
to make an accurate Incision (see diagram). Larynx prom~n t Adam's apple as
First, a vertical cut Is made In the skin, below The vocal cords sit a ma<1<er to locate the best
the tracheal cartilage, and the underlying behind the thyroid Incision site on the neck.
cartilage, al>olre the
muscle and blood vesse Is are carefully moved
point of the incision.
out of the way to expose the trachea.
The trachea is normally held open by
C-shaped rings of cartilage, which prevent the Oesophagus
The oesophagus lies
airway from collapsing. A hole is made between
behind the~ so the
the third and fourth rings, allowing the surgeon st.OgeOn must tal<e care
access to the aj rway without disrupting the not to punciJ.R through
from one to the other.
cartilage supports. A tracheotomy tube is then
inserted into the airway and secured to the
neck. Lithe tracheal opening is going to be a Cartilage ring Trachea
permanent feature rather than temporary then The trachea is held open The trachea CO I oed.s the
a piece of cartilage may be removed to allow the by stiff C-shaped mgs lungs to the mouth and

tube to sit more comfortably. made at cartiage. nose: a tracheotomy

bypasses them to grant
The vocal cords sit just behind the tracheal direct access to the lu:lgs.
cartilage, above the tracheotomy incision site,
but in order to talk, air must be able to pass
through the vocal cords to make them vibrate. Carotid artery
large arteries supplying blood
Some tracheotomy tubes contain unidirectiona l to the brain and face run up
valves, e nabling the patient to breathe in either side of the trachea
through the tube and out through their mouth,
A temporary or
which provides good air supply to the lungs,
permanent tube is
without hampering speech. inserted into the
Thyroid
The thyroid gland,
If the patient is unable to breathe unaided, a trachea through an
responsible for making
incisioo between the
ventilator may be attached to mechanically rings of cartiage.
numerous hormones,
move ah in and out of the lungs. sits just beneath the
tracheotomy site.

Have you got a pen?

A tracheotomy is a complex procedure, so in Flanges
life-threatening, em~gency situations a faster The outer portion at
procedure- known as a cricothyrotomy (also the tube has flanged
called cricothyroidotomy) - may be performed. edges, wtich means it
A higher incision is made just below the thymid can be secuely taped
cartilage (Adam's apple) and then through the to the neck.
cricothyroid ~brane, directly into the trachea.
It is possible to perform this pmcedure with a
sharp instrument and any hollow tube, such as a
straw or a ballpoint pen case. However, finding
the correct location to make the incision is
challenging, and without medical training there
is great risk of damaging major blood vessels,
the oesophagus or the vocal cords.

132
 Answer:
STRANGE Where did hay fever get The term hay f...,.r has nothing to do with hay, and

BUT TRUE its name? e""'Y!hing to do with trees. grasses and ragweed.
The name came about because symptons W'OlAd
strike during hay·har"Vesting season. when these
MISLEADING NAME A Hay allergy B Harvesting C Doctor's name pollens woold be rife.

!•Jf•J\t!I!ll;W•i~W Allergic diseases, including asthma. ore the fifth most common chronic disease in all ages

When summer strikes, why do some of us suffer?

We trample on lawns and mow headaches from blocked sinuses or coughing
them down. but eventually grass caused by mucus dripping down the back of the
gets revenge. Its pollen causes throat from the nose.
many of us to suffer from hay fever, People genetically predisposed to hay fever
and so do trees, weeds and even some fruit. are called atopies. Hay fever usually develops
Despite being smaller than the tip of a pin, during childhood or teenage years, but adults
pollen is carried by the wind and lodges in the can get it too. This is likely to follow repeated
nasal lining tissues and throat, where it can contact with a substance that your immune
cause an allergic reaction. This is when the system perceives as a threat. No one knows for
body mistakenly thinks it has been invaded by sure why hay fever starts affecting someone at
a threat, such as a virus. the point in time it does.
To fight back, the body produces a type of Hay-fever sufferers are in trouble when the
antibody known as immunoglobulin E (IgE) in pollen count reaches 50 pollen grains per cubic
response to the allergen, causing nasal metre of air. You'll experience it worse in the
passages to become inflamed, producing more morning when plants release their pollen.
mucus. This is designed to help flush out the Allergens collect in the air on humid days and
allergens but can lead to other symptoms like during storms, but rain clears the pollen. Too much histamine
Histamine irritates the upper
respiratory passages, making

Why do we get a nynose? them swell and produce the

typical hay feve< symptoms.
An inside look at how pollen Histamine makes your mucus
can affect us Airborne pollen membranes work over time,
Rne dusty pollen is carried producing enough mucus to
by the wind and inhaled flush the pollen out.
through the nasal passage.
Allergy in numbers People with a genetic
15%: Of UK poptjation get disposit ion to hay fever,
hay fever known as atopies, will have
40%: Risk if one parent suffers an alle<gic reaction.
80%: Risk if both parents suffer
95%: Of hay·fever sufferers are
allergic to grass pollen Antibodies ----......iir
1 in S: Affected by hay fever The pollen protein trigge<s
21 milion: UK adults suffer your immune system,
from one or more which creates thousands
type of allergy of antibodies. The
antibodies attach
themselves to mast cells,
which release h istamine
- a substance the body
produces to f ight infection.

Protein problem
Proteins on the surface of the
pollen grain irritate and
inflame the cells that line your
mouth, nose, eyes and throat.
The body's immune system
t reats the pollen like a virus
and takes action to expel it.
 •• I I

The sensory system is what enables us There are thousands of different stimuli that can can cause excruciating pain; this particular
to experience the world. It can also trigger our senses, including light, heat, chemicals condition is known as phantom limb syndrome.
warn us of danger, trigger memories in food and pressure. These 'stimulus modalities' However the sensory system !sable to adapt to
and protect us from damaging stimuli, are then detected by specialised receptors, which change, with the Joss of one often leading to others
such as hot surfaces. The sensory system is highly convert them into sensations such as hot and cold, being heightened. Our senses normally function to
developed, with many components detecting both tastes, images and touch. The incredible receptors gently inhibit each other in order to moderate
physical and emotional properties of the - like the eyes, ears, nose, tongue and skin - have individual sensations. The Joss of sight from
environment. f or example, it can interpret adapted over time to work seamlessly together blindness is thought to lead to strengthening of
chemical molecules in the air into smells, moving and without having to be actively 'switched on'. signals from the ears, nose and tongue. Having
molecules of sound into noises and pressure However, sometimes the sensory system can go said this, it's certainly not universal among the
p laced on the skin into touch. Indeed, some of our wrong. There are hundreds of diseases of the blind, bel ng more common in people who have
senses are so finely tuned they allow reactions senses, which can have both minor effects, or a been blind since a young age or from birth.
within milliseconds of detecting a new sensation. life-changing impact. for example, a blocked ear Similarly, some people who listen to music like to
The five classic senses are sight, hearing, smell, can affect your balance, or a cold your ability to close their eyes, as they claim the Joss of visual
taste and touch. We need senses not only to smell - but these things don't last for long. input can enhance the audio experience.
interpret the world around us, but also to function In contrast, say, after a car accident severing the Although the human sensory system is well
within it. Our senses enable us to modify our spinal cord, the damage can be permanent. There developed, many animals out-perform us. f or
movements and thoughts, and sometimes they are some very specific problems that the sensory example, dogs can hear much higher-pitched
directly feed signals into muscles. The sensory system can bring as well. After an amputation, the sounds, while sharks have a far better sense of
nervous system that lies behind this is made up of brain can still detect signals from the nerves that smell - in fact, they can sniff out a single drop of
receptors, nerves and dedicated parts of the brain. used to connect to the lost limb. These sensations blood in a million drops of water!

134
STRANGE Which creatures can have Answer:
Scallops are an unde.water mollusc that

BUT TRUE up to a hundred eyes? amazingly can have as many as 100 eyes!
Although they can't create as clear a picture as
our eyes, they can detect enough lig:ht and
SIGHT TO BEHOLD A Scallops B Spiders C Peacocks movement to warn them of oncoming predators.

f •lft1\1!ID~'Wil!i!li' Toste ond smell ore closely linked. To test this, pinch your nose os you eot something ond it will toste blond

Retinal neuron Olfactory neuron

Body's messengers These retinal bipolar cells are found in
the eye, transmitting tight signals from
The many fine dendritic arms
of the olfactory cell line the
The sensory system is formed from neurons. These are the rods and cones (where fight is iooersurface of the nasal

1
specialised nerve cells which transmit signals from one ~~ detected) to the ganglion cells, w hich cavity and detect thousands of
~ send impulses into the brain. different smells. or odorants.
end to the other- for example, from your skin to your
brain. They are excitable, meaning that when
stimulated to a certain electrical/chemical threshold
they wilJ fire a signal. There are many different types,
a nd they can interconnect to affect each other's signals.

Purkinje cell
'These are the largest neurons
in the brajn and their many
dendritic arms form multiple Anaxonic neuron
comections. They can both Found within the retina of the
excite and inhibit movement. eye, these oells lack an axon
(nerve fibre) and allow rapid
modification of fight signals
Motor neuron to and from bipolar cells.
These fire impulses
from the brain to the body's
muscles. causing contraction Pyramidal neuron
and thus ll'l<M!Olent. They
These nel.D'ons have a
have lots of extensions (ie triangular cell body, and
they are multipolar) to were thus named after
spread the message rapidly. pyramids. They help
to connect motor
Oeli"'OS together.
Unipolar neuron ----""""-----~
These sensory oeuroos
transduce a physical
stimulus (for example, when
you are touched) into an
electrical impulse.

How do we smell? Olfactory nerve

Find out how our nose New signals are rapidly
and brain work together transmitted via the
to distinguish scents olfactory nerve to the brain,
which collates the data
with sight and taste.

Olfactory bulb
Containing many types of
Total recall
eel . oMactory neurons Have you ever smelt something that
branch out of here through transported you back in time? This is
the cribriform plate bellow. =---• Cribriform plate known as the Madeleine effect because
A bony layer of the skull the writer Marcel Proust once described
with many tiny holes, how the scent of a madeleine cake
Olfactory neuron which allow the fibres of
These neurons are highly
suddenly evoked strong memories and
t he olfactory nerws to emotions from his childhood.
adapted to detect a wide pass from nose to brail.
range of different odours.
The opposite t ype of recall is
voluntary memory, where you actively
try and remember a certain event.
Olfactory Involuntary memories are intertwined
epithelium with emotion and so are often the more
lining the nasal cavity, this
intense of the two. Younger children
layer contains the long
under the age of ten have stronger
extensions of the olfactory
involuntary memory capabilities than
older people, which is why these
neurons and is where
chemical mlltecldes in air memories thrust you back to childhood.
trigger an electric impulse.
Older children use voluntary memory
more often, eg when revising for exams.

135
 =··
sensa

Key nerves
These transmit vital sensory information
to our brain while also sending motor
function signals all around the body

Olfactory nerve
Starting in the nose, this nerw
COI1I.1!rts chemical molerules
irto electrical signals that are
interpreted as distinct odours
Ilia chernoreceptors.

Optic nerve
The optic nerves eorwert tight signals
into electrical impulses. w hich are
interpreted in the occipitall<lbc at the
back of the brain. The resuHing Image
is seen up5ide down and back to front,
but the brain reorients the image.

' '
' '
'
'
. Eye movements Trigeminal nerve
L Touch receptor The trochlea', abd!ICEI'It nos nerve is an example of a
When a IDuch receptor is and oculomotor nerves mechanoreceptor, as k fres when
activated, information about the cu otrol the!!)" muscles yo<r face is touched. It is spit into
strnulus is sent to the spinal cord. tiYee parts,~ the top. middle
and so the cirection in
Reflex actions. wNdl don~ wNdl we look. and bottom thirds of your face.
imlolve the brain. produce rapid
reactions to dangerous stimu~.

Facial and
trigeminal motors
The motor parts of these
nerves control the muscles of
facial express<on (for
example, when you smile),
and the muscles of the
jaw to help you chew.

2. Si~nal sent 3. Motor neurons

to sp1ne feed back
When sensory....,.., The signals b iggol motor
endi 1§15 fire. ...,....,. that iritiate their
information passes own irnpoJses that feed back
tlrough """"' fbres to the muscle. telling ft to
to the spO>al cord move the body part

136
 •• ••
••
•• •• Sensitive skin •
A matter of taste • Smell vs sight • Upsidedown ••• Staying steady
1 Thereareabout9,000taste
buds on the tongue and tf1roaL •
• 2
•• Odoursofferbettermi!I110<Y
recall than ~I cues. as smell
•
•• 3
Human skin contains a.ter half
a million sensory receptors.
•
•• 4 The images formed in the
occipital cortex are upside
•
•
•
5
Ears do more than detect
sound.The fluid and file hairs
These OOill<!rt chemicals found •
• Is tied to emotion. Looking at These are of the highest down, before the brain flips • in t~ inner- ear maintain
in saliva Into electrical .signals, •
• an old photograph can trigger •• concentration W1: the fingerti~
• them. H~ babies start •
• balance. If you sp;n round and
split into fille tastes: swee~ salt. •
•• memory, but a smell can ev<lke •• the ends of the toes and lips, •• by seeing upside down, until •• stop, this fluid is still moving
sour, bitter and umarni. how you lett at the time. • where tl1ey're most needed. the brain learns to adapt • which Is why we get dizzy.
• • • •

!•JfiJt<!l!Ila~I•I~'Q The three smallest bones in the human body - the hammer. anvil and stirrup - ore located in the middle ear

Intermediate nerve
This is a small part of the larger
facial netw. It provides the key
sensation to the forward part of
the tongue to help during eating. Vestibulocochlear
nerve
This nerve provides
sensation to the inner part
of the ear.

J
Glossopharyngeal motor 5 5 5
The motor part of this nerve controls 5 5
5 5 'i 5
the pharynx, helping us ~
5 2 5 5 5 2 5
to speak and breathe normally.
5 5 5 5
2 5 2 2 5 2
5 5 2 2 2 5 5 2 2 2
5 5
5 5 5 5 5 5 5 5 5 5

A patient's sen.se of proprioception

is being put to the test here

~::::::::::~
Vagus nerve
'The vagus nerve is spread aU
around the body. It is a m ixed
sensory and motor nerve, and
is responsible for oontrolting all
of the functioos we don~ think
about - like Oll' heartbeat.

Is there really a
'sixth sense'?
Our sense of balance and the position of our
bodies in space are sensations we rarely think
about and so are sometimes thought of as a
'sixth sense'. There is a whole science behind
them though, and they are collectively called
Vagus motor proprioception. There are nerves located
This portion of the vagus throughout the musculoskelet al syst em (for
nerve can slow" the example, within your muscles, tendons,
heartbeat and breathing ligament s and joints) whose job it is t o send
rate, or increase the information on balance and posture back to the
speed of digestion brain. The brain then interprets this information
rapidly and sends instructions back to the
muscles to allow for fine adjustments in balance.
Since you don't have to think about it and you
can't switch it off, you don't know how vital
these systems are until they're damaged. Sadly
Accessory nerve some medical conditions, including strokes, can
The hypoglossal nerve Connecting the m uscles of the neck affect our sense of proprioception, making it
This nerve controls the to the brail, this nerve lets us tum difficult t o stand, walk, talk and move our limbs.
movements of the tongue. our heads from side to side.

137
 -
=·· •••
ickenpox

•
erstan I
•
I
Discover the biology behind the infamous childhood
ailment and why it never really goes away...
Chickenpox is a strain of the face, arms, legs, stomach and back. These weak immune system or be particularly
Varicella zoster virus, which many develop into fluid-filled blisters and are ohen vulnerable to the disease.
of us have experienced during our accompanied by a fever. The blisters burst, scab After the outbreak, chickenpox doesn't
youth. Most prominent in children, over and fall off within a few days, but new disappear entirely. The disease lies in a
the virus is contracted through coughing and waves of spots can emerge to replace them; it dormant state within the body as your immune
sneezing or transferred on shared objects, usually takes one to two weeks for the body to system keeps it under wraps. The infection can
which makes schools a prime location. regain control. Chickenpox is rarely serious but break out again later and reappear as shingles.
The most famous symptom is the appearance it is important notto interfere with the scabs as A rash builds up on a certain point of the body
of small itchy red spots, which vary in size from infection can make it more severe. and the symptoms return, most commonly in
10-20 millimetres (o-4-0.8 inches) across. The A vaccine is only offered in extreme people over 50. On average, three in everyt,ooo
extent can vary but in most cases they cover the circumstances when an individual may have a people contract shingles in the UK each year.

When chickenpox strikes back... Grown-up

Get under the skin to see how shingles can catch the body unawares chickenpox
90 per cent of adults are immune
if they've had the disease as a
.....--+- - -1----11-- Blisters emerge child but it still affects adults and
Start of the illness - - - Blisters become visible and teenagers. If you develop
The virus infiltrates the Inflamed rashes appear on chickenpox at a later age, all the
skin and causes ,.I-- ._- all affected areas. symptoms are more severe, with
Inflammation and a more chronic pain, headaches and
burning sensation. sore throats; therefore, there is
greater need for treatment, such
as pain relief and soothing creams.
The disease tends to affect
Don't scratch! adults more dramatically as it can
The blisters then now mutate into a variety of other
harden into scabs and strains, such as shingles or, in
fall off. Scratching at extreme cases, lead to
the spots makes the encephalitis, postherpetic
healing process slower. neuralgia or pneumonia. However,
The Varicella virus the chances of this happening are
becomes active
when the immune
system is weak,
overcoming the
.. - Future effects
In around 10·20 per
cent of people who
only around ten per cent.

body's natural have shingles, the

defences. nerve fibres become
damaged which can
Dormancy lead to postherpetic
Once the immune system regains neuralgia (nerve pain).
control, the virus retreats and lies
dormant in the body's nervous
system, but it can return later.

138
 • •
Runny noses . Hush, litUe baby Onion weeping Crocodile tears Darwin's discovery
5 TOP. l li )'OU f1nd that )'OUr nost runS a
lot whonyouay.• ;,-... • 2 Babies typically ay for about
one to three holrs per day. This
.3 Syn·propanethla>S...Ide Is
created by an en:zyme In a cut • 4 While! aocodllos.,.. known far
looking t<ory .. they ... food 5 There is a condifun called the
PseudoBulbar Affect (PBA) in

FACTS l!ltCtu lNrS art I'U"'nhg fr·om

)'OUr I)<IS. down )'OUr ..... duets
and Into-..... .....,;ng
! ean be for a variety rA reasons.
because th?y'n!lulgry, thirsty,
tnd. sca<ed art- just been to
• onion. When it evaporates. this
compot.nd iTitates cu bcrlmiM
glands and taats are ll1ggnd In
~......~~they .....\
Ad. Thtt•.,.sm<'<'elyU>ricato
thtiroyoswhon they..,...Stime
-.llich people aryar ~
~y. FirSt described by
Oartes OarwYl it is often the result
CRYING . _ '""""' orifflos. •
thetalet. ader to cikJte it. outoltht-. rA brain ifluries.

-
I•U•Jtl•IYUW•I@ The overage person will produce 140-28og [5-10oz] of bosol tears per day to keep the eyes moist

The lacrimal Battle of

system the sexes
W hile there is a stereotype that
0 lacrimal gland women are tearier than men,
This gland receives the there is some science to explain
message from the cerebrum the reasons behind this. Studies
to produce tears. have shown that women cry
@ Cornea about four times as often as
Tears help protect the surface men and, while there are
of the eye. cultural factors to be taken into
E) Tear ducts consideration, there are
This is where the water flows biological factors too.
to. If there's too much, it flows Until their adolescent years,
down the face. boys and girts cry fairly equally.
3 Runnynose As testosterone levels rise in
Tears that flow tlvough the boys, they are more likely to get
tear ducts go down a nasal angry than upset. Meanwhile,
passage, which is what girls gain increased oestrogen
causes a runny nose. levels, which modifies
endorphin production, often
leading to more emotional
responses to stimuli.
 168 /
What do
alveoli do? 148
Brain freeze
explained

155
Powering
cells

173
How do we
knowhow
much to
eat?

142 ~eing 153 Eyebrows I Earwax I Sell

y do we grow old? Do we need eyebrows?
ut6 Left or rlret brained?
The truth ehind thinking
154 I:-odem
hour deodorant I
flllin~
How do we com at body odour? 161 Correcting heart rhythms I
ut8 Brain freeze Salt I Adam's apple
Why do we feel this cold pain? 155 What Jthwers your cells? Is salt bad for your heart?
Inside e mitoChondria
149 Runny nose /Coma 162 Seasickness I
What makes your nose run? 156 Can we see thoughts? Rumbling stomachs
Is this sdence or a myth? Explaining seasickness
150 Ears I Freckles I
Sore throat 158 How anaesthesia works 16J What are moles?
Why do your ears pop? The drug that stops pain signals A look a mole formation
151 Memory I Toothpaste I 159 Stomach ulcers I 164 Brain control/ Laughing
~durlils Mouth ulcers Do our brains control us?
at is a memory? How do ulcers form?
165 Dandruff I Eye adjustment I
152 Blus~ I Caffeine I Fainting 160 Hair growth I Blond hair Distance the e!e can see
Tbetellt esignsofblushing Our hair explained Revealing how andruff forms

140
 VVhathappenstothe
human body as we age?
The whys of ageing. at its most basic our cells can no longer function. Free radicals- Infirmities associated with ageing that have to do
level, seem simple: over the course of our unstable oxygen molecules that are a natural with stiffening or hardening of tissues, such as
lives, our bodies simply wear out Or by-product of cell function- can build up and bond atherosclerosis.
that's what we've been led to believe, to other cells. As a result, DNA can be damaged. They Cells can also mutate on a geneliclevel due to
anyway. Scientists who study gerontology, or the may also result in protein cross-linking. or environmental or other factors. Problems with
process of ageing. don't yet have a deflnltlve answer glycosylalion, a phenomenon by which protein mitochondria, structures that proVide energy inside
as towhyweage. There are two schools of thought molecules in our bodies inappropriately bond cells, can cause cells to die as well as diseases
Thewear-and-tearconcept-meaning our cells are together. Theyaren'taselaslicanddon'tmoveor associated with old age such as Alzheimer's disease.
used up over time- that many people subscribe to Is break down like they're supposed to. Another group of theories puts forth the idea that
just one example of an error theory. There's some eVidence for this theory- wrinkles, our life spans are predetermined or programmed.
Proponents of the error theory believe that for example, are caused by a breakdown of collagen, One scenario suggests that the biological clock is
random external events cause damage that builds a type of protein found in the skin. Protein cross- 'set' by both our neuroendocrine system, which
up inourbodiesoverthe course of our llfetlmeumll linking may also be responsible for a lot of produces hormones, and our immune system. The

142
 •••
• • •
•• •
• ••
•• •
•• •:• Loss of hearing
STOP Grey hair
1 When your hair tLITlS grey has
Wrinkles
2 The loss of siOn elasticity also •3
: Missing teeth
•
•
: Loss of eyesight
•: 4 of
• •5•

FACTS
Enamel on our teeth wears With ageing can come a number Age-related hearing loss can
a tot to do with your genetics. ages us tiTough the creation of : down OYer time and vision problems that can : be caused by everyttjng from
but the loss of melanin wrinkles, although in some : maintaining dental hygiene : cause a loss of sight. including : environmental factors to a
associated with gey hair is cases it can be prevented or at ! becomes more difficult, : cataracts, gl:auccma and : degeneration of the fine hair
SIGNS OF AGEING due to older age. teast slowed down. : resufting in tooth loss. : maci.Aar degeneration.. : cells in the oochlea.

I•U•~•I!l!3N•1MP The process of ageing by o living system, or organism. is known os orgonismol senescence

Age spot
Ageing skin
What looks like spots and
Slll damage, as well as
the ageing process in
general, can cause
Shaft
The hair shaft itself is
composed of keratin, a
dumps of melanin to Each hair follicle in our heads fibrous protein.
wrinkles is actually a number of concentrate into spots. contains melanin - a pigment that
changes going on under the skin Epidermis
The skin is kept smoolh by gives our hair its colour. Over time the
the proteins collagen and melanin production decreases and
Younger e&ast:in, which break down unpigmented hair begins to grow
and lose their stretch """'"
bne, causing V111'i'*les..
Hair bulb
The bulb is at the base of Hair root
the root It cootains the The root comprises three layers
follide, which forms a - the outer root the inne< root
socket for the hair. and the bub - which gilleS hair
its structure and rigidity.

- Papilla - - Cortex
This specialised cell is fed by Hair colour is
the bloodstream and is detennined through
responsible for the growth the cortex, which is
of new hairs, and their part of the shaft of
rn.mber of pigment cells- visible hair.

Subcutaneous fat layer - - ---" Greying

As we age, the fat pads under the skin
Older A reduction in
diminish and cause siOn and muscle to sag. melanin production
causes hair to grey.

hypothalamus in the brain sends instead of8o (the average life span in
messages via hormones to the pituitary developed countries}. Most researchers
gland, which in tum stimulates or believe that ageing is a complex process Hair loss
restricts hormone secretions by the that no single theory can explain - it's a A full head of hair
thyroid, adrenal glands, ovaries and combination of our genes, our biological will thin as the
autoimiTM.lne system
even the testicles. functions and environmental factors. attacks the follicles.
Over time this complex system does We tend to focus more on the visible
not function as effidenlly, leading to signs of ageing at first, like WTi nldes and
everything from problems sleeping to grey hairs, and these changes are prime
menopause (which is a normal part of examples of how complicated the
ageingforwomen,butcanleadto process can be. We've already talked a
additional health problems}. bit about the cause of wrinkles: the
Different types of cells in the connective tissues collagen and elastin,
immune system decline in number as that keep skin looking smooth, both
we age and do notfunctionas well. Some break down over time. Without the firm
scientists point to the fact that the overall connections underneath, the skin sags.
risk of contracting cancers goes up as we Many people Jose fat deposits in their
get older; younger, more efficient faces, and the skin's oil production
immune systems may have been able to decreases. Many of these things have a Wrinkles
These d"""'op
fend them off. genetic component, but outside factors as collagen and
Or it could all simply be genetic. That such as exposure to ultraviolet radiation skin cells begin
is, our DNA tells our bodies when life is at and smoking both cause wrinkles and to deteriorate.
an end. There does seem to be a genetic sags faster. The Sun's rays break down
component to ageing among most connective tissues, while smoking
animals - they have predictable life causes blood vessels to contract.
spans. Women also tend to live longer Grey hair is caused by a Joss of
than men. if your parents lived a long melanin, the pigment that is responsible
time, you are more likely to do so for our hair colour. Only recently have
yourself. One group of genes, known as scientists learned that melanin Hearing loss
The sensory hair eels in the
the longevity assurance gene. ha been production gets interrupted when
cochlea deteriorate,
determined to influence life span. Ifyou hydrogen peroxide levels in the body Skin tone causing age-related hearing
inherit the 'helpful' version then you are increase over time. Other proteins found Decreased
loss, known as presbycusis.
subcutaneous fat
more likely to have a longer life. ln hair cells that are responsible for
and elastic tissues
Although our genes play a part in our regrowth diminish over time too. Unlike cause sagging.
lifespan, obviously they can be with wrinkles, however, there isn't much
influenced or changed. Otherwise. we'd you can do to avoid going grey other than
still be living to the ripe old age of 30 dye your hair. Genetics doappearto play

143
 Old age explained
a part, though.lfyourparentswent corresponding decrease In growth
factors (hormones or proteins that

Bone loss
grey at a young age, Itis likely that you
wiJI too. stimulate ceil growth). Loss of tone in
The internal signs ofageing are muscles such as the anal sphincter
more serious, health-wise, than the and the bladder can cause one of the
external ones. When and how they most embarrassing signs ofageingfor Acondition that affects ageing bones
occur are also based on a wide many people: Incontinence. Osteoporosis Is a degenerative bone disease that resu Its In lower bone density,
variety of factors. Some gerontologists The ageing brain Is still very which makes the bones weak and fragile. The rlskoffalllngaswellas breaking
like to generalise that some parts of mysterious compared with what we bones Increases as thedlseaseworsens.ltlscaused by a loss of the minerals that
the body get harder as we age, while know about the rest of the human make up bone, such as ca!dum. There Is a genetic factor, and the decrease of sex
others get softer, but everything Is body. It was once thought that hormones 1n both genders Increase the likelihood of developing osteoporosis.
interconnected. As we mentioned age-related Issues such as memory
before, arteries get harder due to a loss bad to do with a decrease in
buildup of plaque. The heart builds neurons. Now, however, researchers
up pressure because It has to work believe that unless you have a specific
more to pump blood through the disease that damages neurons,
harder, narrower blood vessels, complex chemical processes are
which results In high blood pressure. more likely to blame. For example,
Other muscles. like the lungs, get the brains of people with Alzheimer's
harder due to calcium deposits. disease tend to have deposits of
These can be caused by hormonal fibrous proteins called amyloids. The
changes or from havtng serious exact cause remains unknown,
infections such as tuberculosis. although one current theory Is that
Meanwhile, hormonal changes the amyloids manage to get into the
cause calcium to leech from the brain because the system that
bones, maklngthemsoftandbrtttle regulates the exchange of blood in
and redud ng their density. Known as the braln, known as the blood-brain
osteoporosis, this loss means that barrier, malfunctions.
we're at a greater risk of breaking What is arguably most fascinating
bones. Sarcopenla, or loss of muscle about the ageing process Is that it's
mass, Is another 'soft' sign of ageing. different for everyone and it's
Muscles contain special cells called unpredictable In so many ways.
satellites, a form of stem cell. These Thanks to the advances being made
cells are responsible for muscle in medicine, we're learning more L Healthy bone 2. Bone with osteoporosis
growth as well as regeneration when every day about not only what causes Healthy bones """"'"' tight. Benes with osteopclrosis have
there's some form of damage. These the most unpleasant signs of ageing. sbong strucnns and are allle to gapped. porous strucl1.-es. They
cells gradually become less proficient but also what we can possibly do to easiy ._.body weight in are fragile and can frac:nn easiy,
counteract them. most circ:unstances. as_. as lead totals.
over time, possibly due to a

3. Puberty 5. Adulthood
The seven
stages of man r This growth spurt
indicates the start
of sexual matlrity.
Girls tend to reach
puberty two years
Muscles are
de~~eloped and
strong. Organs are
fully functional.
6. Late adulthood
After middle age tissues
begin to deteriorate and
weaken, while hair loses
its pigmen tation.
What are the principal earlier than boys.

stages of the visible

human ageing process
throughout our lives?

L Infancy
The oompletely
dependent irian\
experiences rapid
physical growth.

2 . Childhood 4. YOlll9 adulthood

TISSUe. muscle and A period of increasing
bonethengrow physical rnattmy and body
gr.Waily IIIIi puberty. ~
144
 1. Nutritional MORE DRASTIC 2.Honnone 3. Plastic
changes therapy surgery
Antioxidants such as vitamin E The visible signs of <)9eiog
1The use of hotrnon~ such
and calorie·restrictive dets as human gl'owth hormone can be combated -
have both been shown to to combat signs of ageing, temporarily - through
exteOO life span. but not such as decreased muscle SIXgery and other
without potential health rlsl<s. mass. Is verycontrover"Sial cosmetic pr-ooedur~

I•U•~•I!l!3N•1MP Ageing changes con be universal [happen to most people] or probabilistic [only occur in some people]

Life
aroun the world
LEurope
Mucho!Europeenjoysa
!; 5. Asia
Aslahasnearlyeveryrangeofllfe
healthy life expectancy of more : expectancy within its borders.
75-77.5
than?Zyears. G. Japan
72.5-75 2. North America japan Is the Asian count:rywilh
10-72.5 canadianshaveasUghtlyhlgher i the highest average Ute
67.5-70
65-67.5
...,o llfeexpectancythanAmericans. i expectancy on the continent
3. South America t 7. Indonesia
60-65 The largest country has one of : lndonesla Is roughly on a par
55-60 the lowest life expectandes. : withmucho!Asia
50-55 4.Africa 8. Australia and
45-50 Most of Africa, being New Zealand
40-45 undeveloped, has much lower !r These industrialised countries
0 -4 0 life expectancy. : have an 8o+ life expectancy.

7. Old age - --,

A more elder1y
appearance results
Slowing
•
down the
from wrinkles, hair
loss and decreased
muscle tone.
age1ng process
Although ageing itself is inevitable (at least currently),
there's a lot that we can do to slow down the ageing
process. Vlsible signs ofageing like wrinkles can be
diminished by avoiding Sun exposure and other risk
factors like smoking. Internal signs ofageing can all be
combated to some extent by lifestyle changes. Weight-
beaTing exerdsessuch as weight-lifting, for example,
have been shown to help maintain bone density and
stave off osteoporosis.Aerobic exercise like walking or
cycling can prevent weight gain- which leads to
numerous diseases and conditions that age us - as well
as improve cardiovascular health. Diet also plays a part
in ageing - a balanced one can not only reduce the risk of
diseases like type two diabetes but also keep our
immune systems operating at their peak for longer.
Some researchers treat ageing like a disease. To that
end, stem-cell treatments and even cryogenics are
looked to as a potential cure. But at what cost? Others
feel that we weren't meant to live forever and should Thereareanumberofways to
focus on ways to age comfortably. slowdowntheagelngprocess

145
 I
ow we think

• •
or r1 ra1ne
Actually, you're neither. Discover the truth behind the way we think
It's true that the different sides of of over t,ooo people, in order to determine local hubs, each responsible for a different
the brain perform different tasks, whether the networks on one side of the brain set of functions.
but do these anatomical were stronger than the networks on the other. Hubs with related functions cluster
asymmetries really define our Despite the popularity of the left versus right together, preferentially developing on the
personalities? Some psychologists argue that brain myth, the team found no difference in the same side of the brain, and a llowing the nerves
creative, artistic individuals have a more strength of the networks in each hemisphere, to communicate rapidly on a local scale. One
developed right hemisphere, while analytical, or in the amount we use either side of our example is language processing - in most
logical people rely more heavily on the left side brains. Instead, they showed that the brain is people, the regions of the brain involved in
of the brain, but so far, the evidence for this more like a network of computers. Local nerves speech, communication and verbal reasoning
two-sided split has been lacking. can communicate more efficiently than distant are a ll located on the left-band side.
In a study published In the journal PLOS ONE, ones, so instead of sending every signal across Some areas ofthe brain are lesssymetrical
a team at the University of Utah attempted to from one hemisphere of the brain to the other, than others, but both hemispheres are used
answer the question. They divided the brain up neurones that need to be in constant relatively equally. There is nothing to say you
into 7,ooo regions and analysed the fMRI scans communication tend to develop into organised can't be a brilliant scientist and a great artist.

Examining the human brain Parietal lobe

(pressure, taste)
[l Occipital lobe - - .
What do the different parts of the brain actually do? The parietal lobes handle (vision)
sensory information and Incoming information
are involved in spatial from the eyes is
awareness and navigation. processed at the
Broca's ar•~a·------------, back of the brain in
(speech) the visual rortex.
Broca's area is responsible
for the ability to speak and
is almost always found on
the left side of the brain.

Frontal lobe - - - - - - - - .
(planning,
problem solving)
At the front of each
hemisphere is a frontal
lobe, the left side is more
heavily involved in speech
and verbal reasoning,
while the right side
handles attention.

Auditory cortex - - - -
(hearing)
The auditory cortex is
responsible for processing
information from the ears
and can be found on both
sides of the brain, in the
temporal lobes.
Temporal lobe
(hearing1 facial Wernicke's area
recognition, memory) (speech
The temporal lobes are processing)
involved in language The region of the brain
processing and visual memory. responsible for speech
processing is found on
the left-hand side.

146
I•U•Jtl!I!JI3~1•l!.'i> It is a myth that we only use ten per cent of our brains. even at rest. almost o/1 brain regions are active

. . .• ,,
Give your brain a
fun workout
Boost your memory
l Look at this list of items for one minute,
then cover the page and see how many you
can remember:

Coin Telephone Grape

Duck Potato Pillowcase

It took 82,944
computer processors Key Teacup Bicycle
40 minutes to simulate
just one second of
human brain activity,
Pencil Match Table
it's that powerful

Difficult? Try again, but this time, make up a

'Myth-taken identity story in your head, linking the objects
The left vs right brain personality myth is actually left, they couldn't describe it. Speech and language together in a narrative.
based on Nobel Prize-winning science. In the are processed on the left side of the brain, but the
1940s, a radical treatment tor epilepsy was trialled; information from the left eye is processed on the
doctors severed the corpus callosum of a smaH right. The patients were unable to say what they
number of patients, effectively splitting their brains saw, but they could draw it. Psychologists
in two. If a patient was shown an object in their wondered whether the differences between the
right field of view, they had no ditloculty naming it, two hemispheres could create two distinctive
but if they were shown the same object from the personality types, left-brained and right-brained .

1tlll0:
•
Left
•
... BAit ~
~
Right
...You get the idea. Make it as silly as you like;
strange things are much more memorable
than the mundane.
Emotional Slow brain ageing
Rational
2 Learning a new language is one ofthe
best ways to keep your brain active. Here are
four new ways to say hello:

Problem solving Creative • Polish: Czesc! - ~

lche-sh-ch)
s
J
• Russian: ZdravstvuJ· ~
lzdrah-stvooy)
•
~

Precise Intuitive
• Arabic: Marhaba /[7"-':::::::=:...::,_~"~ ..
lmar-ba-ba) ..,
· Swahili: Hujambo
fhud-yambo)

logical Spiritual

Dog lovers Cat lovers

147
 I
rain freeze
•
IS '
•
That intense pain you sometimes get when
you eat ice cream too fast is technically
called sphenopalatine ganglioneuralgia,
and it's related to migraine headaches
The pain of a brain freeze, also know as an Ice cream headache, comes from
your body's natural reaction to cold. When your body senses cold, it wants
to conserve heat. One of the steps It takes to accomplish this is constricting
the blood vessels nearyourskln. With less blood flowing nearyourskin,
less heat is carried away from yourcore, l<eeplngyou nice and warm.
The same thing happens when somethl ng really cold hits the back ofyour mouth.
The blood vessels In your palate constrict rapidly. When the cold goes away {because
you swallowed the ice cream or cold beverage), they rapidly dilate back to their
standard, normal state.
This is harmless, but a major facial nerve called the trigeminal lies close to your
palate and this nerve interprets the constriction/dilation process as pain. The location
of the trigeminal nerve can cause the pain to seem like Its coming from your forehead.
Doctors believe this same misinterpretation of blood vessel constriction/dilation is the
cause of the intense pain of a migraine headache.

"A major
facio/ neNe
___., coiled the
The Oplrthalmic brardl - - - -
trigeminal
carries sensory messages
from the eyeball, tear gland. lies close to
._.:~per nose, upper eyelid,
forehead, ard scalp. your palate"

The Mardibular branch

carries sensory signaJs
from the skin, teeth and
gums of the lowe- jaw, as
~I as tongue, chin, lower
lip and skin of the
temporal region.

~-+------- TheMaxitaryboadlcarries
sensory messages from the
The bigenio ... facial- skin, gums and teeth of the
is positjoo IOd ._y close IX> ._.:>per jaw, cheek, ._.:>per lip,
the palate. nos,.,.,., lower nose and lower eyeid.
merprets palate blood
vessel 001 tSb i:OOn cn:t
cilation as pah - -

148
 at makes your nose run?
Discover what is going on inside a blocked nose and why it gets runny when we're ill
It surprises many people but the main Cilia Mucus Goblet cell Epithelial cells
Tiny balr.fike The glycoprotelns that
The lining of!he nose Tbe nose Is llned
culprit responsible for a blocked and has many mucus- by epithelial cells,
stn.ICtuJeS move make up mucus dissolveIn
runny nose Is typtca Uy not excess mucus towards lhe water, forming a gel-like producing goblet cells. ~redlncllla

mucus butswelltngand Inflammation. back ollhe lhroat so substance !hat traps debris.
lithe nose becomes infected, or an allergic tbatlt can be Themorewater, !he runnier
swallowed. !he mucus.
reaction is triggered, the lm mune system produces
large quantities of chemica I messengers that cause
the local blood vessels in the lining oft he nose to
dilate. This enables more white blood cells to enter
the area, helping to combat the infection, but It a lso
causes the blood vessels to become lea l<y, al low! ng
fluid to bulld up In the tissues.
Decongestant medicine contains a chemica I that's
simllar to adrenaline, which causes the blood
vessels to constrict. stopping them from leaking.

' \

Connective
tissue
Beneath Lhe cells
lining Lhe nose Is a
layer of rollJlettlve
tissue that Is rlcb
In blood vessels.

Macrophage Blood vessels

Cells of lhe Immune lnflammatorychemlcalslgnals
system produce chemical cause blood vessels to dilate,
mediators like histamine, allowing water to seep Into the

-.
which cause local blood tissues, diluting the mucus and
vessels to become leaky. maklnglt runny. •

How do we bring a
person out of a coma?
When we talk about 'bringing Doctors induce the coma
someone out of a coma', we are using a controlled dose of
referencing medically Induced drugs. To bring the person out
comas. A patient with a of the coma, they simply stop
trnumatlc btaln Injury Is the treatment Bringing the
deliberately put Into a deep patient out of the coma doesn't
state of unconsciousness In wake them immediately. They
order to reduce swelllng and grndually regain consciousness
allow the btaln to rest When over days, weeks or longer.
the btaln Is injured, Some people make a full
it becomes inflamed. The recovery, others need
swelling damages the brain rehabilltatlon or lifetime care
because It Is squashed Inside and othersmayr.:>main
the skull. unaware of their surroundings.

149
 I
Ears popping 1 Sore throats 1 Freckles

Why do our
'pop' on planes?
The eardrum Is a thin membrane that helps to transmit sound. Air
pressure Is exerted on both sides of the eardrum; with the
surroundlngatmospherlcpressurepushingitinwardswbileair
being delivered via a rube between the back of yournose and the
eardrum pushes it outwards. Tills tube Is called the Eustachian tube, when
youswallowotopensanda small bubble of air Is able to move causing a 'pop'.
Rapid altitude changes In planes make the 'pop' much more noticeable
due to bigger differences In pressure. Air pressure decreases as a plane
ascends; hence air must exit the Eustachian tubes to equalise these pressures,
again causing a ·pop'. Conversely, as a plane descends, theairpressurestarts
to increase; therefore the Eustachian tubes must open to allow through more
air in order to equalise the pressureagatn, causlnganother'pop·.

What are freckles?

Freckles are clusters of the pigment melanin. It is
produced by melanocytes deep In the skin, with greater
concentrations giving rise to darker skin tones, and
hence, eth nIdly. MeIa nl n protects the skin against
harmful ultravloletsunlight, but Is also found In other locations
around the body,. Freckles are mosllygenelically inherited, but not
always. They become more prominent during sunlight exposure,
as the melanocytes are triggered to Increase production of melanin,
leading to a darker complexion. People with freckles generally have
pale skin tones, and lftheystayln the Sun for too long they can
damage their skin cells, leadlngtoskln cancers llke melanoma

Why does hot honey

and lemon
throat when it's sore?
Honey and lemon can be areas. This means it will be less

t9 drank warm as a comfort

remedy when suffering
• from a sore throat or cold,
painful when these areas come into
contact with other surfaces when you
eat or swallow.
Lemon also helps to settle the
and is a populardrlnkwlth many
who are feellng unwell. The Idea Is stomach too, as it contains acid,
thathoneycoatsthetbroatand which can be particularly helpful
therefore any inJlamedareaswlll be whenexperiencinganupsetstomacb
'protected' by a layer of honey, while from the effects of a cold or other
at the same time soothing painful digestion-related illness.

150
 How epidurals work
The science behind blocking pain explained
An epidural(meaning 'above 1. Epidural space 6. Processing
the dura') is a form of local The outer part of the Anaesthetic in the blood is filtered
spinal canal, this cavity is out by theliver and kidneys, then
anaesthetic used to typically about 7mm leaves the body in urine. The effects
completely block pain while (0.8il1) wide in adults. usually wear off a couple of hours
a patient remains conscious. It involves after the initial injection.
the careful insertion of a fine needle
deep into an area of the spine between
two vertebrae of the lower back.
This cavity is called the epidural
space. Anaesthetic medication is
injected into this cavity to relieve pain
or n umb an area ofthe body by reducing
sensation and blocking the nerve roots
that transmit signals to the brain.
The resulting anaesthetic medication 2. Epidural needle
After sterilising the area, a
causes a warm feeling and numbness needle is inserted into the
leading to the area being fully interspinous ligament until
anaesthetised after about 20 minutes. there is oo more

What is a Depending on the length of the

procedure, a top-up may be required.
resistance to the injection
ol air or saline solution.

memory? This form of pain relief bas been used

widely for many years, particularly Bladder
Memory Is the brain's
post-surgery and during childbirth.

t9 ability to reca II
information from the past
• and it generally falls Into
three categories- sensory, short-term
3. Anaesthetic ------..
Through a fine catheter in the
needle, anaesthetic is carefully
and long-term. introduced to the space
Look at this page then close your surrounding the spinal dura.
eyes and try to remember what It
looks like. Your ability to reca II what
this page looks like is an example of
your sensory memory. Depending on M --"-- 4. Absorption
Over about 20 minutes 5. Radicular arteries
whether or not this page is Important The anterior and posterior radicular
the anaesthetic
to you will be the de term Inlng factor medication is broken arteries run with the ventral and
in how likely ills thatit wlli get passed down and absorbed Into dorsal nerve roots, respectively,
on to your short-term memory. the local fatty tissues. which are blocked by the drug.
Can you rememberthe last thing
you did before reading thls?That is
your short-term memory and Is a bit
like a temporary storage facility where How does toothpaste for
the less-Important stuff can decay.
whereas the more Important stuff can
end up in the long-term memory.
sensitive teeth work?
Imagine just one of your teeth. It has two thinner and they may have a receded gum line
Our senses are constantly bel ng
primarysections: the crown located above exposlngmoredentine. Therefore, the enamel and
bombarded with Information.
the gum line and the root below it. Tbe gums offer less protection and, as such, this is what
Electrical and chemical signals travel crown comprises the foUowing layers from makes their teeth sensitive.
from our eyes, ears, nose, touch and top to bottom: enamel. dentine and the pulp gum. Sensitive toothpaste works by either numbing tooth
taste receptors and the brain then Nerves branch from the root to the pulp gum. Tbe sensitivity, or by blocking the tubules in the dentine.
makessenseoftheseslgnals. When dentine runs ro the root and contains a large number of Those thai numb usually contain potassium nitrate,
we remember something, our brain tubules or microscopic pores, which run from the which calms the nerve of the tooth. The toothpastes
refires the same neural pathways outside of the tooth right to the nerve in the pulp gum. that block tbe tubules in the dentine usually contain a
along which the original information People with sensitive teeth experience pain when chemical called strontium chloride. Repeated use
travelled. You are almost reliving the their teeth are exposed to something bot. cold or when builds up a strong barrier by plugging the tubules more
experience by remembering lt. pressure is applied. Their layer of enamel may be and more.

151
 ·ne I Blushing 1 Fointin

Whyandhow
do we blush?
Blushing occurs when an excess of blood
Red glow flows Into the small blood vesselsjust
Oled<s l1n1 red wlile blushing under the surface of the skin. Facial skin
ca.e to blood vessels being near has more capillary loops and vessels, and
the sl<ns suface. vessels are nearerthesurfaceso blushing is most
visible on the cheeks, but may be seen across the
whole face. The small muscles in the vessels are
controlled by the nervous system.
Blushing can be affected by factorssuchasheat,
illness, medicines, alcohol, spicy foods, allergic
reactions and emotions. Ifyou feel guilty, angry,
Nervousness excited or embarrassed, you will involuntarily
Being embarrassed releases release ad rena II ne, which sends the automatic
adrenaline, which stimulates nervous system Into overdrive. Your breathing wUI
the ne''"''" system. increase, heart rate quicken, pupils dilate, blood will
be redl rected from your digestive system to your
muscles, and you blush because your blood vessels
dilate to Improve oxygen flow around the body; this
is all to prepare you for a Hght or flight situation. The
psychology of blushing remains elusive; some
scientists even believe we have evolved to display
our emotions, toactasa public apology.

"Blushing con
be affected by
heat, illness,
medicines and
spicy foods"
What makes
caffeine so
addictive? Fainting, or 'syncope', is a
temporary loss of consciousness
due to a lack of oxygen to the
When we are awake the naturally
occurring brain chemical adenosine brain. It Is preceded by dizziness,
is drawn to fast moving receptors In nausea, sweating and blurred Vision.
the brain. As adenosine attaches to
the receptors it slows them down, which causes us
to feel sleepy.
The receptor cells confuse caffeine for
, The most common cause is
overstlmulallon of the body's vagus nerve.
Possible triggers of this include intense
stress and paIn, standing up for long pertods
adenosine cells and as such willingly bond to lt. or exposure to something unpleasant.
The action doesn't slow down the receptor's Severe coughing, exerclseand even
movement as adenosine would and as the space Is urinating can sometimes produce a similar
usurped they are unable to sense adenosl ne so the response. Oversll mulation of the vagus
cells speed up, Increasing neuron firing in the nerve results In dilation of the body's blood
brain. The pltuarygland interprets this as a fight vessels and a reduction of the heart rate.
or flight scenario so releases hormones to alert the These two changes together mean that the
adrenal glands to produce adrenaline. This results body struggles to pump blood up to the

--...___
In dilated pupils, a racing heart and an Increase In brain a gal nstgravlry. Alack of blood to the
blood pressure. The liver also releases sugar Into brain means there Is not enough oxygen for
the bloodstream for an instant energy boost. it to funcllon properly and fainting occurs.

152
 LTea 2.lnstant 3. Ground
In a survey by the coffee coffee
Food Standards The level of caffeine pl'esent Gr'ound coffee. however',
Agency. the mean In instant coffee was oot contains the most c-affeine.
amount of caffeine much mote with an avefage The mean level was lOSmg.
fOIXld in too was of 54mg ot caffeine per in SOI"'le cases tanglng as
400>;1 per cup. fegular sef'Vlng. high as 254mg per serving.

What is Where is the self

earwax? in the brain?
Until recently, neuroscientists had thought it
Earwax is a substance that can be
fanciful to speculate about the physical substrates
found in the ear canal of humans of such high-level phenomena as consciousness
and other mammals. Medically it
and 'the self', but recent advances in functional
is referred to as cerumen and neuroimagingare enabling us to make significant in-roads into
consists of dead skin, hair and water-soluble
these questions. Researchers have identified a core brain
secretions from the outer ear canal. lt serves
network, the 'default-mode network', which accounts for much
several functions - one of which Is as an of the brain's metabolism and appears to support a background
antibacterial, self-cleaning lubricant. Excess
level of consciousness, of the sort associated with day-
cerumen usually finds its way out of the ear
dreaming or mind-wandering. Crucially, the default-mode
canal through the washing of hair and jaw
network becomes especially activated during self-judgments,
movement. Occasionally it can collect and get
as well as other high-level, species-specific behaviours such as
compacted which can lead to tinnitus. taklnganotherperson's point of view, or thinking outside of the
moment to contemplate the pastor future. The default-mode
network decreases In activity and connectivity during states of
Why do we have eyebrows? reduced consciousness such as sleep or anaesthesia, and is
known to exist only in a primitive form In infants and lower
Eyebrows are very important for diverting we were sweating a lot ltis quite easy primates. Using functional magnetic resonance imaging
moisture, such as salty sweat, away from our to see how this could have had an (fMRI), we recently found that the psychedelic drug, psilocybin,
eyes due to their distinctive arch shape. evolutionary advantage in terms of the active component of'maglc mushrooms', also decreases
This would obviously be useful for escaping predators. Sweat also causes activity and connectivity in the default-mode network - in a
allowing us to see clearly ifit was raining or If irritation in the eyes. manner that correlates with loss ofself, or 'ego-disintegration'.

153
 I
72-hour deodorants 1 Fillings

How 72-hour deodorants work

Discover the chemistry that helps us combat body odour for up to days at a time
Deodorants prevent Most deodorants also contain
the odour associated antiperspirants, which prevent
with sweating, either sweating from occurring at aLL
by masking it, or by These are usually aluminium-
killing the bacteria responsible. To based compounds. The aluminium
make the effects last longer, the is taken up by the cells that line the
active ingredients are sometimes openings of the ducts that carry
encased within microcapsules. As sweat to the surface of the skin.
the capsules take up water from As the aluminium moves into
sweat they burst, releasing the cells, it takes water with it,
deodorisingchemicals. By causing the cells to swell and
including capsules of a variety of closing off the ducts. Depending on Antiperspirants cause cells
sizes, each requiring a different the type of aluminium compound to swell and the ducts to
close up, preventing
amount of water to burst, the used, the effect will last for sweating altogether
duration can be extended. different lengths of time.

odern fillings Is metal bad?

Traditional silver-coloured 'amalgam' fillings are
made from mixed metals, and are often
Composite resins are replacing traditional comprised of around 50 per cent mercury.
Historical evidence suggests that this type of
metal fillings, but what are they made of? filling has been in use since around 650 A.D, and
despite the advances in composite materials, the
amalgam filling is still in use to this day.
. -- layering There has been much controversy over the
Curing - - - - - - - - - - - - - ,
A ight is used to trigger a
chemical reaction within
! The liqlid composite resn is
applied in layers. After eacll
biological safety of amalgam fillings though, and
concerns have been raised regarding mercury
the resil\ causing the layer, the composite is cased released into the body, as well as into the
material to harden. environment. However, as it stands, no causal
link between health complaints and amalgam
Composite resin
fillings has been proven. In fact, they still provide
Dental composites are
Finishing touches - - - - - - - - - , some advantages over composite fillings, and
A piece of carbon paper is used made from a resin matrix
reQuire significantly less repair and replacement.
to test whether the bite lines containing ilorganic
up properly, and the filling is materials, ll<e silica, for
smoothed down accordingly. durability.

' - - - - -- Acid
A controlled amount of acid
is appled to the drilled tooth
Pri mer - -------.J to generate mic~holes for
A priming agent is brushed the filing to bind to.
onto the prepared tooth
su1ace to enable the filing
to adhere properly. ' - - Base
In deeper filings, • cement
base made from glass
iol o 11er or zh: phosphate IS
added to ns.Jate the nene
from lelo- ature changes.
Decay - -
The decayed poi WId the
tooth is ren MJ'IIed u:sng a
~IW;tNs
generates a solid platform
for the filng to stick to.

~::::::::~::::::::::::::::::::~ ~

154
 Answer:
STRANGE Who do you inherit The DNA within mltochoodr'la is only from youl'

BUT TRUE mitochondria from?

mothel''s egg. The corresponding DNA fl'om yout
father's sperm is destroyed aftel' fer-tlisatioo. This
means l'eseal'cherscao ttack back unchanged
INHERITED AT BIRTH A Father B Mother C Grandparent maternal inheritance lines many b.Jndteds of years.

l•){•m!I!Il:i~~WJP Mitochondrial disease occurs when mitochondria malfunction - there is o huge variety of symptoms

at rs your •
Discover how mitochondria produce all the energy your body needs
Mitochondria are known as the maintain life- by controlling Krebs Cycle which They are deeply linked with evolution of all
batteries of cells because they use is the set of reactions that produce ATP. life. It is believed mitochondria formed over a
food to make energy. Muscle fibres Mitochondria are found in nearly every cell billion years ago from two different cells, where
need energy for us to move and in your body. They are found in most eukaryotic the larger cell enveloped the other. The outer
brain cells need power to communicate with the cells, which have nucleus and other organelles cell became dependent on the inner one for
rest of the body. They generate energy, called bound by a cell membrane. This means cells energy, while the inner cell was reliant on the
adenosine triphosphate (ATP), by combining without these features, such as red blood cells, outer one for protection.
oxygen with food molecules like glucose. don't contain mitochondria. Their numbers This inner cell evolved to become a
However, mitochondria are true biological also vary based on the individual cell types, mitochondrion, and the outer cells evolved to
multi-taskers, as they are also involved with with high-energy cells, like heart cells, form building blocks for larger cell structures.
signalling between cells, cell growth and the containing many thousands. Mitochondria are This process is known as the endosymbiotic
cell cycle. Theyperform all of these functions by vital for most life - human beings, animals and theory, which is Ancient Greek for 'living
regulating metabolism -the processes that plants all have them, although bacteria don't. together within.'

Inside the mitochondria ,... --- - - - - Phospholipid

Take a t our of the cell's energy f actory bilayer
Every mitochondria has
ATP synthesis - - - - - - - - - - . . . . , a double-layered
ATP is the basic energy unit of the cell surface composed of
and is produced by ATP synthase phosphates and lipids.
enzymes on the inner membrane at its
interaction with the matrix. . - - - - Outer membrane
The outer membrane contains
large gateway proteins, which
Mit ochondrial DNA - - control passage of substances
Mitochondria have their through the cell wall.
own DNA and can divide to
pro'dlJ(:e copies. - - Inner membrane
This layer contains the
key proteins that
regulate energy
production inside the
m itochondria, including
ATP synthase.

Inter-membrane
space
This contains proteins
and ions that control How many are
what is able to pass in
and out of the organelle in a cell?
via concentration The number of mitochondria in a
gradients and ion pumps. cell depends on how active that
particular cell is and how much
- - - - - Cristae energy it requires to function. As a
The many folds of the general rule, they can either be low
inner membrane energy without a single
increase the surface mitochondrion, or high energy with
area, allowing greater thousands per cell. Examples of
energy production for high-energy cells are heart muscles
high·activity cells. or the busy liver cells, which are
active even when you're asleep,
and are packed with mitochondria
:;-- - - - - - Matrix to keep functioning. If you train
The mitochondrial matrix your muscles at the gym, those
contains the enzymes, ribosomes cells will develop more
and DNA, which are essential to mitochondria as an adaptive
allowing the complex energy- mechanism to help provide energy. e;
producing reactions to occur. Q

155
 ind reading

How can we view the brain?

Computed Magnetic n!SOflai1Ce Functional MRI (fMRO
~<en ima!jng (MRO This form of MRJ uses blood-
ThlscomblnesmultlpleX-rays MRI uses strong magnetic oxygen-level-dependent
to see the bones of tbe skull fields to align lhe protons In (BOLD) contrast. followed by a
and soft tissue of tbe brain-It's water molecules In various strong magnetic field, to detect
lhe most common scan used body parts. When used In tiny changes In oxygen-rich
afte.r trauma, to detect injuries tbe braln, It allows lnlrlcale and oxygen-poor blood. By
to blood vessels and swelll ng. anatomical detail to be showing pictures to lnvoke
However, It can only give a visualised. It has formed the certain emotions, fMRI can
snapshot of tbe structure so baslsofnoveltechnlques to reveal which areas are active
can't capture our thoughts. visualise thought processes. durlngpartlculartboughts.
 CTscan ' 2 . BRAIN 1\JMOURSj 3DMRI PET scan
el
Fast and easily accessible TheSI! 3D scans show lntrlcato This functional imaging
24 hours a day, these is alowh) researchers
• anatomical details of b<aln
scans can identify
life-dveatering bleeding a~ . t"",· ' tumours, partk:ula~y In relotlon to
the SUf'T'OU"'dWlg stl\iCtwts. This
to test nO'oi'el drugs and
treatments to preven1
withW. the sku:Ufor ~. enables doct01'5 to de\Ormlne W progression of this
net.II'OSU'geon to stop.
g ·~
'.: . they ean bo safely removed 0< not
=::~=~~==~,..~~:lo~ous train disorder.__
l•ll•fil•IIH3~1•1Vd CT sconnrng of the brorn wos invented in the early-Seventies

Imag •
Alzheimer's disease is a potentially
debiUtatlng condition, which can lead
to severe dementia. The ability to
diagnose it accurately and early on has
driven the need for modem imaging
Diffusion tensor Posibon emission
techniques. The above image shows a
inaging (0 I I) tDmography (PE I)
This MRivarlant rel.leson the This bleeding-edge technology
PET scan. The right-hand side of the
direction of water diffusion detects gamma rays emitted Image (as you look at it) shows a normal
within tissue. When a magnetic from blologlcally acttve tissues brain, with a good volume and activity
gradient lsappUed. thewater based on glurose.lt can pick range. On the left-hand side is a patient
aligns and. when t.befield Is up unusual biological activity, affected by Alzheimer's. The brain is
removed. t.be wate.r dllluses such as that from cancer. There
according to a tissue's Internal bave been recent advances to
shrunken with fewer folds, and a lower
structure. Thlsallowsa)D romblne PET with CTor MRI to range of activity- biologically speaking,
Image of activity to he built up. obtain lots of data quickly, there are far fewer neurons firing.
 I
Anaesthesia

•
owanaest 1awo
By interfering with nerve transmission these special drugs stop
pain signals from reaching the brain during operations - - - - - - - Memory
General anaesthetic affects
the ability to form memot ies;
Anaesthetics are a form of drug widely The body under the patient doesnl remember
used to prevent pain associated with
surgery. They fall Into two main
general anaesthetic the operation and often woo'!
recall coming to either.

categories: local and general. Local What happens to various parts of

the body when we're put under?
anaesthetics can bee!therappl!ed directly to the
skin or injected. They are used to numb small areas
without affecting consciousness, so the patient wi ll Brain activity - - - - - '
remain awake throughout a procedure. Electroencephalograms (EEGs) Airway
show that the electrical
Local anaesthetics provide a short-term blockade Loss of consciousness and
activity in the brain drops to a muscle relaxation suppress
of nerve transmission, prevent! ngsensory neurons state deeper than sleep, breathing and prevent
from sending paln signals to the bra! n. Information mimicking a coma. coughing, so a tube and
is transmitted along nerves by the movement of ventilator are used to
maintain the airway.
sodium ions down a carefully mal ntalned
electrochemical gradient Local anaesthetics cut Nil by mouth - - - - - -
General anaesthetics .._-ess
off sodium channels, preventing the Ions from
the gag reflex and can cause
travelling through the membrane and stopping '«ll'l')jti~sotoprevent

electrical signals travelling along the nerve. cholcing pal:iei ots must not eat
Local anaesthesia isn'tspeciHcto pain nerves, so it beforeanopeatioo.
will also stop information passing from the brain to
tbe muscles, causing temporary paralysis.
General anaesthetics, meanwhile, are Inhaled
Thecirruatory systEm is
and injected medications that act on the central slowed by anaesthetic, so
nervous system (brain and spinal cordi to Induce a heart rate, blood preSSlR
temporary coma, causing unconsciousness, muscle and blood oxygen areal
continuously monitored
relaxation, pain relief and am nes!a.
It's not known for sure how general anaesthetics
Pain neurons
'shut down· the brain, but thereareseveral proposed Unlike with local
mechanisms. Many general anaesthetics dissolve In anaesthetic, pain
neurons still fire under
fats and are thought to Interfere with the lipid
general a naesthesia,
membrane that surrounds nerve cells In the brain. but the brain does
They also disrupt neurotransmitter receptors, not process the
Many anaesthetics
signals properly.
altering transmission of the chemical signals that let cause nausea. Often
nerve cells communicate with one another. antiemetic drugs that
prevent V<miting are
given after su-ge<y.
Comfortably numb
If large areas need to be anaesthetised while the
patient is still awake, local anaesthetics can be
injected around bundles of nerves. By preventing
transmission through a section of a large nerve,
the signals from all of the smaller nerves that
feed into it can't reach the brain. For example,
injecting anaesthetic around the maxillary nerve
will not only generate numbness in the roof of
the mouth and aHof the teeth on that side, but
will stop nerve transmission from the nose and
sinuses too. local anaesthetics can also be
injected into the epidural space in the spinal Muscle relaxation ----~~
canal. This prevents nerve transmission through A mJSde relaxa-lt is often
the spinal roots, blocking the transmission of administered with the
information to the brain. The epidural procedure anaesthetic; this causes
is often used to mollify pain during childbirth. paralysis and enables lower
doses of anaesthe!ic to be used

158
 2005
Stress and diet are blamed StOf'l'lach add Is proposed as Two Australian scientists The fii'St antibiotics ar~ Barty M..WII and Robin
for stomach ulcer'S. Patients the cause of gastric ulcers .shov.l that H P)lfori causes approved for treatment Warren are awa(ded a
ate prescribed rest and and antacid treatment is stomach uk:ers, but some of the infection that joint Nobel prize fOf'
bland food, like oatmeal introduced to countes- il ~sceptical to begin with. causes stomach ulcers. their 1982 discovery.

l•){•m!I!Il:i~~W.A'P The scientists who revealed bacteria caused gastric ulcers had to drink their own experiment to prove it!

causes stomach ulcers?

Originally thought to be the result of stress, we now know that bacteria are the culprits...
Normally a th id< layer of An ulcer in the making Gastrin
alkaline mucus
Once bacteria breach the stomach lining, it can The Inflammatory
effectively protects the no longer protect itself from its acidic contents ... response Increases
cells lining the stomach production of the
from the low pH of stomach acid. If hormone gastrin. This
Neutralising Helicobacter pylori In tum stimulates the
this mucus becomes disrupted, stomach formation of more
Bacteria burrow tbrougb the
however, add comes into contact acid mucus In the stomach to escape
with the organ's lining_ damaging H pylori break damagebyadcL Theystlcktothe
down urea to ceUsofthelnleriorUnlng.
the cells and resulting in an ulcer. make ammonia.
Around 6o per cent ofstomach Thlslsusedto
ulcers are caused by inflammation produce ,-
bicarbonate to ~
due to chronic Infection by the neutralise
bacterium Helicobacter pylori. dangerous
Bacterial by-products damage the stomach add.
cells lining the stomach, causing a
breakdown of the top layers of tissue.
Non-steroidal anti-inflammatory
drugs (NSAIDs}, like ibuprofen and
aspirin, also cause stomach ulcers in
large doses. They disrupt the
enzymes responsible for mucus
production, diminishing the ~--- Damage
As the cells become
protective barrier. damaged a wound opens
Enzymes upln !be stomach wall. If
Hpylori produce proteases this becomes deep enough It
and phosphoUpases- can perforate blood vessels
enzymes thatdamage the Theammonlamadeby causing bleeding.
proteins and cell the bacteria as a defence
membranes of the against add damages the
stomach cells. cells lining !bestomach,
causing Inflammation.

Why do we sometimes
get mouth ulcers?
Ulcers are small lesions usually In other cases, recurrent ulcers may
triggered by physical damage to the be symptomatic of conditions
inside of the mouth, for example including 812 or iron deficiencies,
biting your cheel< accidentally, gastrointestinal diseases or
eating sharp food or brushing your immunosuppressant diseases such
teeth. They are very rarely as HIV. Ulcers are sometimes
contagious and usually heal within triggered by sensitivity to certain
ten days. Recurrent ulcers have a foods including strawberries,
variety of causes, the most common almonds, tomatoes, cheese,
being stress and hormonal changes. chocolate and coffee.

~ "The.Y ore rarely contagious

i onousuol/y heal in ten days"
159
 Why does blond
hair look darker
when it's wet?
Dry blond hair has a rough, Uledsurface- somethinglike fish
scales. When light rays hit these scales, they bounce off in all
directions. Some ofthe light reaches your eyes and makes the
hair look brighter; It's like shining a torch on the hair.
When you wash your hair, a thin Him of water forms around each fibre.
Ught rays pass Into the film of water, bounce around Inside, and there's
a chance they'll get absorbed by the hair. Since the light gets trapped
inside the water, less of It reaches your eyes, so the hair actually appears
lot darker.

"A thtn film of water forms

around each fibre"

How quickly does

human ha·
Human hair grows on average 1.25 centimetres (0.5 inches)

t9 per month, which Is equivalent to about 15 centimetres

(six Inches) per year. There are several variables that can
• affect hair's growth rate such as age, health and genetics.
Each hair grows In three stages, the first being the anagen phase
where most growth occurs. The longer your halrremalnsin this stage
dictates how long and quickly It develops; this can last between two
and eight years and Is followed by the catagen (transitional) and
telogen (resting) phases. Ha lr growth rates vary across different areas
of the head, with that on the crown growing the fastest.

I "Each hair grows in three

stages, the first being the
onogen phose where most
growth occurs"
160
Correcting heart hms
How can a little electricity be used to fix a heart that's beating off-kilter?

rr - - - - - - 8. low energy 3. Timing the shock ~

ResettWlg an abo mal The heilrt is wherable when it
heart beat uses fairly is between beats, so to prE'IIeOt
law-energy shocks of just a cardiac arrest, the shock is
50·200 joules. ti'ood to coincide with the
pumping of the ventricles.
6. Natural pacemaker
The heart has i1S own internal
pacemaker known as the skloatrial
node. Delivering a small electric
shock to this resynchronises the
BEFORE CARDIOVERSION
orgoo's natural electrical activity.
4. Arrhythmia - --+....
~ the heart bealS too fast, or
at an irregular pace~ it
becomes unable to
effectively p~ blood
around the body.
5. Electric shocks
low-energy electric shocks
are deiM!red to the heilrt ~ -- L Paddles
tlvough the electrodes. Two metalic plates are Atrial fibrillation
placed on the patient's
chest across the heart.

AFTER CARDIOVERSION

7. Cardioversion
machine
The maciWle recoo ds the
electrical activity of the
heilrt and calculates the A. ,..- A. ~
2. Conductive gel electric shocks reqund
A saltwateM>ased gel is to restore the orgoo to
used so the current can its nonnal mytlm.
triM!! from the elect1'0des NonnaiECG
and tlvough the skln.

Why's salt Do women have

bad for Adam's apple?
the heart? You may not realise, but actually everyone bas an

Simply put, too much salt Is bad for

you as It increases the demand on
t9 Adam's apple, but men's are usually easier to see in
their throat. It's a bump on the neck that moves
• when you swallow, named after the biblical Adam
Supposedly, It's a chunk of the Garden of Eden's forbidden fruit
your heart to pump blood around the stuck in his descendants' throats, but it's actually a bump on the
body. This is because when you eat thyroid carUiagesurroundlngthevoice box. Thyroid cartilage is
salt it causes the body to retain shield-shaped and theAdam'sapple is the bit at the front.
Increased quantities of water, which Why do men'sAdam·sapplesstlck out more?Tbls is partly
increases your blood pressure, and because they have bonier necks, but It isafso because their
this places morestralnon your heart. larynxes grow differently from women's during puberty to
As such, most doctors recommend accommodate their longer, thicker vocal cords, wbicbgivetbem
moderating daUy salt intake. deeper voices.

161
 I
mbling stomach 1 Seasickness

ca
a b
Oesophagus
This muscular pipe
Discover how the small connects the throat
to the stomach.
intestine is really to blame...
Waves ol Involuntary muscle
contractions called peristalsis churn Stomach
rood Is churnedand
the food we eat to soften It and mixed with gastric
transport It through the digestive juices to help It to
system. The contractions are caused by strong breakdown.
muscles in the oesophagus wall, which take just
ten seconds to push food down to the stomach.
Muscles in the stomach churn food and gastric
juices to break it down further.
Then, a Iter lour hours, the sem1-dlgested
liquefied food moves on to the small Intestine
where yet more powerful muscle contractions
force the food down through the Intestine's bends
and folds. This is where the rumbling occurs. Air
from gaseous foods or that swallowed when we eat
-often due to talking or Inhaling through the nose
while chewing food- also ends up In the small
intestine, and it's this combination of liquid and
gas in a small space that causes the gu rgling noise.
Rumbling is louder the less food present In the Smal intestine
small intestine, which Is partly why people Here. liquid food
combined with trapped
associate rumbling tummies with hunger. The gases can make lorsome
other reason is that although the stomach may be embarrassing noises.
clear, the brain still triggers perlsta Isis at regular
intervals to rid the intestines of any remaining
food. This creates a hollow feeling that causes you
to feel hungry.

"Then, after four Large intestine

rood passes from the
--;.-~.

hours, the semi- small Intestine to the

large lntesllnewbere

digested liquefied It Is turned Into faeces.

food moves to the

small intestine"
Are seasickness and altitude
sickness the same thing?
No, they're not -altitude sickness Is a collection signals' about a moving environment-for
of symptoms brought on when you're suddenly Instance, when your eyes tell you that your
exposed to a high-altitude environment with lnunediate surroundings (such as a ship's
lower air pressure so less oxygen enters our body. cabin) are still as a rock, while your sense of
The symptoms can include a headache, fatigue, balance(andyourstomachl)teUyousomething
d lzzi ness and nausea. quite different.
Seasickness, on the other hallQ, Is a more Thlslsthereason wbyclosingyoureyesor
general feeling of nausea that's thought to be taking a turn out on deck will often help, as it
caused when your brain and senses get 'mixed reconciles the two opposing sensations.

162
 are
These small skin blemishes are
common, but what are they and why
must we keep a close eye on them?
Amole on the skl n, or a vigilant if a new one appears on the skin or
melanocyticnaevus, !san If an existing mole begins to change. A
abnormal collecllon of the malignant melanoma is a rare kindolskin
pigment cells called cancer that can occur in melanocytes.
melanocytes. Some moles can be present at Although rare, malignant melanomas
birth (congenital melanocytlc naevi) but cause the majority of the deaths related to
most develop spontaneously later In life, skin cancer.llyou're partlcularlymoley
usually as a result of exposure to sunlight. you're more susceptible to melanoma and
Moles are often brown or black (pigmented should try to avoid too much sunlight.
naevl)andareusually round or oval, but Moles to watch are dysplastic naevi,
they can be a variety or dlllerentshapes
and sizes. Growth and change over tlme Is
which are large, irregularly shaped moles
of mixed colouration. They often have "A malignant melanoma is o
quite normal.
Moles sound pretty unremarkable and
paler, jagged edges with darker centres
and tend to be accompanied by a lot or
rare k1nd of skin cancer that
are harmless In natttre, and yet we must be other moles on the body. con occur 1n melonocytes"

Melanocyte Hairs
liars are made from filamentous bicrnaterialthat
The sldn's natur.11 Dipigla111nelelnt'lt, melanin, is a protein
produce.d in eels caled melanocytes. Melanocytes Epidermis
are usually spn>ad evenly tlroughaut ll1e sldn for This is the outer layer of
...,., colow. Melanin also absorbs IN raciation. you' sldn and it contar.s
lolJ!jl, flat eels.
Melanocytesare
b::ated in the dell I Ms
and epidermis.

•
MeJanoma
"""'*' with • farrily history ol Dennis
~melanomas and those who
haYe been exposed to a lot of Slright The denuis is the layer that
are most at risk from tl'is 1.11000 •trollable COIISisls of blood wssels,
!J'OWih of P9nel 11 eels. glands and""""" encings.

163
 I
rain control 1 Laughing
Do we control our brains or
do our brains control us?
.
An experiment at the Max Planck Institute, Berlin, in2008

t9 showed that when you decide to move your hand, the decision
can be seen In your brain, with an MRI scanner, before you are
• aware you have made a decision. The delay Is around six
seconds. During that lime, your mind Is made up but your consciousness
doesn't acknowledge the decision unUI your hand moves. One
interpretallon oflhls Is that your consciousness- the thing you think ofas
'you'-is justa passenger inside a deterministic automaton. Your
unconsdous brain and your body get on with runnl ng your lt fe, and only
report back to your conscious mind to preserve a sense of free wHI. But it's
just as valid to say that when you make a decision, there's always
background processing going on, which the conscious mind Ignores for
convenience. In the sa me way, your eye projects an upside-down image
f
onto your retina, but your unconscious brain turns It the right way around.

we
Which muscles react when we find
something funlly and why is
laughter so harcfto fake?
Laughing can pull the facial expression upward;
somellrnes be on top of this, the zygomaticus major
completely involuntary also pulls the upper lip upward
and involves a complex and outward.
series of muscles, which is why It's so The sound of our laugh is
difficult to fake and also why an produced by the same mechanisms
active effort is required to suppress which are used for coughing and
laughter in moments of sudden speaking: namely, the lungs and the
hilarity at inopportune moments. Ia rynx. When we're breathing
In the face, the zygomaticus major normally, air from the lungs passes
and minor anchor at the cheekbones freely through the completely open
and stretch down towards the jaw to vocal cords In the larynx. When they
close, alrcannotpass, however
when they'repartlallyopen, they
generate some form of sound.
Laughter is the result when we
exhale while the vocal cords close,
with the respiratory muscles
perlodica lly activating to produce
the characteristic rhythmic sound
of laughing.
The risorius muscle is used to
smile, but affects a smaller portion
of the face and is easier to control
than the zygomatic muscles. As a
resu It, the risorius is more often
used to feign amusement, hence
why fake laughter is easy to detect
by other humans.

"Laughter is produced by the some mechanisms

used for coughing ond speaking"
164
What is the maximum What is dandruff?
Dandruff Is when dead skin cells fall off the scalp. This

distance the hu Is normal,asourskin Is always being renewed. About

half the popu latlon of the world suffers from an
excessive a mount of this shedding, which can be
eye see? triggered by things like temperature or the increased activity ofa
microorganism that normally lives In everyone's skin, known as
Dust. water vapour and pollution In thealrw!ll rarelyletyouseemorelhan malassezla globosa. Dandruff Is not contagious and there are many
20 kilometres, even on a clear day. Often, the curvature of the Earth gets in treatments available, the most common Is specialised shampoo.
the way first- eg at sea level, the horl20n Is only 4-Bkm away. On the top of Mt
Everest. you could theoretically see for339km, bulln practice cloud gets In
the way. For a truly unobstructed view, look up. On a clear night, you can see
the Andromeda galaxy with the naked eye, which Is 2.25 million light years away.

Why do eyes
take a while to
adjust to dark?
At the back of the eye on the retina, there
are two types ofphotoreceptors (cells
which detect light). Cones deal with
colour and Hnedetallandactin bright
light, while rods deal with vision in low-light
situations. In the Hrst few minutes of moving into a
dark room, cones are responsible for vision but
provide a poor picture. Once the rods become more
active, they take over and create a much better
picture In poor llghL Once you move back into light
the rods are resetandso dark-adaption will take a
lew moments again. Soldiers are trained to close or
cover one eye at night when moving in and out of a
bright room, or when using a torch, to protect their
night vision. Once back In the dark, they reopen the
closed eye with the rods still working and, as a
result, maintain good vision. This allows them to
keep operating In a potentially hostile environment
at peak operational efficiency. Give it a try next time
you get up In the middle of the night, it may help you
avoid tripping over In the dark.

165
 I
Allergies 1 Eczema
do SOtne people
haveal and
don't?
Allergies can be caused by two things: host and
environ mental factors. Host Is if you inherit an allergy or are
likely to get It due to your age, sex or racial group.
Environmental factors can Include things such as pollution,
epidemic diseases and diet. People who are likely to develop allergies
have a cond ilion known as 'atopy'. Atopy is not an illness but an
inherited feature, which makes individuals more likely to develop an
allergic disorder. Atopy tends to run In families.
The reason why atopic people have a tendency to develop allergic
disorders is because they have the ability to produce the allergy
antibody called 'Immunoglobulin E' or'lgE' when they come into
contact with a particular substance. However, not everyone who has
inherited the tendency to be atopic wiLl develop an allergic disorder.

"People who ore likely

to develop allergies
hove a condition known
as 'atopy"'

Eczema explained
What causes the skin to react to otherwise harmless material? •
Eczema ls a broad term for a
Under the skin
t9 range of skin conditions, but
the most common form is
• atopic dermatitis. People with
What happens inside the body when eczema flares up?

this condition have very reactive skin, Ceramides

The membranes of skin cells contain waxy lipids
which mounts an inflammatory response to prevent moisb.re evaporation, but these are
when in contact with Irritants and often deficient in eczema
allergens. Mast cells release histamine, Allergen
which can lead to itching and scratching, Allergen •
** entry route
The cells of the skn are

*
Eczema is commonly triggered
forming sores open to Infection. normally tightly bound
by the same things as many
There is thought to be a genetic allergies- anything from pet
together to prevent
contaminants from
element to the disease and a gene hair to certain types of food
entemg the body, but in
involved in retaining water in the skin eczema there are gaps..
has been identified as a potentia I
contributor, but there are many factors.
Eczema can be treated with steroids,
which suppress immune system
Water loss
activity, dampening the inflammation The skin is less able Inflammatory
so skin can heaL In serious cases, toretai1waler,
immunosuppressant drugs - used to leading to dcyness • response
The irnrnu1e system
prevent transplant rejection - can
actually be used to weaken the immune
and in latiol L
• • -gel
produces a response to
IS beneath the skin,
leading to redr II!SS, itd1i 1!1
system so it no longer causes and also inflammation
inflammation in the skin.

166
 do Is it for to
go have an allergy to
Arare condition called aquagenlc contains water, the condition hinders intimacy.
urticaria is often referred to as an Death could occur when water is swallowed if
allergy to water. The symptoms of the throat swells up, blocking the airway. The
aquagenlc urticaria are painful but root cause Is unknown. One hypothesis is that
Sometimes we trip over or hurt generally not fatal. Contact with water- H20 generates a toxic compound in the outer
ourselves In other ways. When It containing substances can bring out sore hives layers of the skin, prompting the release of
happens some of our blood vessels
on thesurfaceoftheskin, cause a burning histamines. Reactions can sometimes be
break, blood plies up under our skin
sensation and induce headaches. Because saliva controlled with antihistamines.
and we can see this as a bruise. These nasty
things have the famlllar 'black and blue· or
purple appearance In the beginning but
gradually change Into different colours.
The purple colour Is given by haemoglobl n, a
protein that carries the oxygen In our red blood
cells. Our body reacts to this with some white
blood cells called phagocytes ·eating up· the
materials in the bruise. As the phagocytes
degrade the haemoglobin, they turn It Into other
molecules. Different molecules show different
colours and the bruise will changecolourwlth
time to green, yellow and brown. When
everything has been cleared up by your
immune system the bruise disappears and
you're ready to bump into something else.

The purple 1s given

by haemoglobin"

Is
bad for you?
Is this substance as evil as we hear?
Cholesterol Is a fatty molecu le In the blood and, generally

t9 speaking, having too much is bad: itcanstickto the walls of

your arteries and increase the rtskofheart disease. Most
• foods, with the exception of offal, eggs and shellfish, don't
contain any cholesterol, but many contain saturated fats, which are
turned Into cholesterol by the liver. However, cholesterol itselfisn't
unhealthy-In fact. you wouldn't beabletollvewlthoutilThe body uses
cholesterol as a kind of padding. coating the outer membranes of all our
cells and insulallng nerve Hbres, helpingslgnals travel properly to and
from the brain.lt'salsoa fundamental partoftheendocrinesystem,as
all steroid hormones (eg oestrogen) are synthesised from cholesteroL
Importantly, a good, balanced diet and regular exercise can keep
cholesterol easily within a healthy range for most people.

"Cholesterol itself isn 't

unhealthy - in fact, you
wouldn'toe able to ffve
without it"
167
 I
Alveoli onotom

•
I
you reat e?
The lungs are filled with tiny
balloon-like sacs that keep you alive
Gas exchange occurs in the lungs, blod<s of each are the tiny alveolus. They are blood within the capillary venous system on
where toxic gases (carbon dioxide) the final point of the respiratory tract, as the the other side of the epithelial layer.
are exchanged for fresh air with its bronchi break down into smaller and smaller The alveoli of the lungs have evolved to
unused oxygen content. Of all the tubes, leading to the alveoli, which are grouped become specialised structures, maximising
processes in the body that keep us functioning together and look like microscopic bunches of their efficiency. Their walls are extremely thin
and alive, this is the most important. Without it, grapes. Around the alveoli is the epithelial layer and yet very sturdy. Pulmonary surfactant is a
we would quickly become unconscious through -which is amazingly only a single cell thick- thin liquid layer made from lipids and proteins
accumulation of carbon dioxide within the and this is surrounded by extremely small that coats of all the alveoli, reduces their
bloodstream, which would poison the brain. blood vessels called capillaries. It is here that surface tension and prevents them crumpling
The two lungs (left and right) are made up of vital gas exchange takes place between the when we breathe out. Without them, the lungs
several lobes, and the fundamental building fresh air in the lungs and the deoxygenated would collapse.

Alveoli anatomy Type I pneumocytes

These large, flattened cells form Breathe in,
How alveoli enable gas exchange 95 per cent of the surface area of
an alveolus, and are the very thin breathe out
diffusion barriers for gases. The alveoli function to allow gas
exchange, but since they're so
Type II small, they can't move new air
r---pneumocytes inside and out from the body
These thicker cells form without help. That's what your
the remaining surface area respiratory muscles and ribs do,
of the alveoli. They secrete hence why your chest moves as
surfactant, which prevents you breathe. The diaphragm,
the thin alveoli collapsing. which sits below your heart and
lungs but above your abdominal
organs, is the main muscle of
respiration. When it contracts, the
Oxygenated blood normally dome-shaped diaphragm
The freshly oxygenated f lattens and the space within the
blood is taken away by chest cavity expands. This
capillaries and enters the reduces the pressure compared to
left side of the heart, the outside atmosphere, so air
to be pumped rushes in. When the diaphragm
through the body. relaxes, it returns to its dome
shape, the pressure within the
chest increases and the old air-
now full of expired carbon dioxide
- is forced out again. The muscles
between the ribs (called
intercostal muscles) are used
when forceful respiration is
required, such as during exercise
Try taking a deep breath and
observe how both your chest
expands to reduce the pressure!

Macrophages
One cell thick ---''"' These are defence
The alveolus wall is just The capillary veins bring cells that digest
one cell thick, separated deoxygenated blood from the bacteria and particles
from the blood capillaries right side of the heart, which present in air, or that
by an equally thin has been used by the body have escaped from the
basement membrane. and now contains toxic C02 • blood capillaries.

168
 • • •'
Blue eyes ••• Blil*ing •
Sight ••• Tears
••
•• Measure ments
1share
PeoPle with blue eyes all
a common ancestor. A
• 2 Your eyes
•
wiU blink around
15-20times per minute and
•• 3 Technically. you see with
your brain and not your
•
•
4 Toars are not only an
ctmOllonal response; they
••
•
5
On average, a human eyebatl
is around 2.Scm (lin) in
genetic mutation about •• it last for around 100 • eyes. Poor vision sometimes also hnlp prevent your eyes •• diameter and weighs as
LO.OOO years ago gave miUiseconds. You also blink • sterns from problems with from drying up and get rid Utile as 7.5g (0.25oz). A
someone blue eyes. whm more when talking than
••
the visual cortex of the brain of any IITltatlng particles ••• giant squid's eyeball Is ten
everyOne elso's were brown. when reading. and not the eye itsetf. that could cause damage. • times as big as a human1s.

-
(I)(•M•I!NtW•l!j!G> SAD is more common in women and people between the ages of 15 and 55

How do dilating eye

drops work?
Discover how they are used to diagnose and treat eye conditions
Sight is one ou r most Important
senses, so maintalnlnggood eye
health is absolutely essential.
However, eyes ight problems can be
difficult to detect or treat on the surface, so
specialist eye doctors will often use dilating
eye drops in order to get a better took Inside the
eye a t the lens, retina and optic nerve.
The drops contain the active Ingredient
atropine, which works by temporarily relaxing
the muscle that constricts the pupil, enabling it
to remain enla rged for a longer period of time
so a thorough examination can be performed.
Some dilating eye drops also relax the muscle
that focuses the lens inside the eye, which
allows an eye doctor or optometrist to measure
a prescription for young children who can't
perform traditional reading tests.
Dilating eye drops are not only used to help
perform procedures, they may also be
administered after treatment, as they can
prevent scar tissue from forming. They are a lso
occasionally prescribed to ch lid ren with
lazy-eye conditions, as they will temporarily
blur vision in the strong eye, causing the brain
to use and strengthen the weaker eye.

Those who suffer from also often reported, with pain

migraines know they are sometimes subsiding after the
a constant concern as sufferer has been sick.
they are liable to strike It is thought that migraines occur
a t any time. Essentially, a migraine when levels of serotonin in the brain
is an intense pain at the front or on drop rapidly. This causes blood
one side of the head. This usually vessels in the cortex to narrow,
takes the form of a heavy throbbing which is caused by the brain
sensation and can last as little as an spasrning. The blood vessels widen
hourortwoand up to a few days. again in response, causing the
Other symptoms of a migraine intense headache. Emotional
include increased sensitivity to upheaval is often cited as a cause for
light, sound and smell, so isolation the drop in serotonin in the brain, as
ina dark and quiet room often is a dlet in which blood-sugar levels
brings relief. Nausea and vomiting is rise and fall dramatically.
 I

1\Nins are becoming more prevalent due to medical

developments, but how and why do they occur?
The number of twins, or multiples, dizygotic twins. Also, if the mother is going
being born Is actual ty on the rise through fertility treatments, she is much more
due to the Increase In use of fertility
treatments such as tvr as people
likely to become pregnant with multiples.
It will become apparent quite early on that a
mother is carrying twins as this is often picked
but
wait longer to have ch Udren. The number of
twins surviving early births Is also Increasing
due to improved medical knowledge.
However, twins are still a relatively rare
up during early ultrasound scans. There can be
other indications such as increased weight gain
or extreme fatigue. Although twins are often
true...
There are many stories of Identical twins being
occurrence making up only around two per born entirely healthy and go on to develop separated at birth and then growing up to lead
cent of the living world's population. Within without problems later in life due to medical very similar lives. One example described in the
this, monozygotic twins Ifrom one ovum) make advances, twins can be premature and smaller 198<> january edition of Reader's Digest tells of
up around eight per cent with dizygotic Ifrom than single births due to space constrictions two twins separated at birth, both named james,
two ovum) seen to be far more common. within the womb during development who both pursued law-enforcement training and
While the.re is no known reason for had a talent for carpentry. One named his son
the occurrence of the split of the ovum that jamesAlan, and the other named hisjames Allan
causes monozygotic twins, the chances of
having twins is thought to be affected by "It is believed twins and both named thelr dogsToy. There were also
the Mow forth twins, two Identical brothers who
several different factors. It Is believed twins
'run in the family', often seeming to skip
'run in the ft:;Jmily ', lived 8o miles apart In the UK, dying of exactly the
same symptoms on thesamenlghtwithin hours of
generations, while the age, weight, height. race often seemtng to each other.
and even diet of the mother are thought to
potentially Impact the chances of conceiving
skip generations"
170
 •• ••
• •• •
•• •• Race affects conception :• Most children •••
12 foetus wolid record • Nonuplets exist • Quad gestation
STOP 1 Although sadlyttwspregnancy •2• A Malaysian mother gave birth
rrve boys and four girls in
•••
3 is seen to be a higher ••
4
••• With regard to OZ twins, there ••• The highest recorded number
of children had by one woman
••
•
••
5
With regard to quadruplets.

FACTS
cid not reach fuU term and no : to the average gestation period is
babies SUI"o'ived, a woman in •• March 1999 ... none survived prevalence of these twins in • is the first wife of F'eoclor • just 32 weeks - that's eight
Algentina was observed to have • 0'\lef six OOLrS. Another set of
• black Africans, and a lower • Vassilyev, who ived in the • weeks shcw'ter thanusua~
• • • •
• •
MULTIPLE BIRTHS
12 foetuses inside her worrtl
from natural conception.
•• noruplets suffered a similar fate
;n~neym197L ••
incidence than to be expected
in Oriental mothers. •
•
• 1700s. She gave birth to an
incredible 69 dlldren.
••• primarily due to the size
restriction of the womb.

I•U•~•I!l!3N•1MP Female monozygotic twins ore more common due to the increased likelihood of mole mortality in the womb

•
M
There are many difficulties with twin they're joined.lf it is by a vital organ or bone
pregnancies- mainlydue to the limited size structure. one or both may die following birth
of the mother's womb. Multiple pregnandes as they grow - or during an operation to
rarely reach full term due to these limits, separate them.
twins averaging at around 37 weeks. Also, It is also suspected that as many as one in
because of the lack of space and eggs splitting eight pregnandes may have started out as a
in the womb, further complicationssuch as potential multiple birth, but one or more of the
conjoined twins can occur. Conjoined twins foetuses does not progress through
can be a problem dependant on where development to full term.

Placenta Twins inside

Provides a metabolic
interchange between
the twils and mother.
the womb
Uterine wall
• - - - - The protective wall
of the uterus.

Amniotic sac - - - LSpenn

A thin-walled sac that ferti6ses egg
surrounds the fetus In MZ twins, only ooe
during pregnancy. 2. Fertilised

Atsomep<Mnt~
egg splits
early on, the fertili~ "
+ egg and one sperm
are irwolved.

egg will split and two

separate foetuses wiD
start to form. These
wil be genetically
identical.
I \
Umbilical cord
A rope-like cord
connecting the fetus
to the placenta.

Cervix
I 3.Spenn
The lower part of the fertilise
uterus that projects
separate
into the vagina.
'------ eggs
In DZ twins, two
separate eggs are
fertilised by
4.Separate different sperm.
eggs These will implant
From studying identical, monozygotic twins, different parents. Often we see a similar IQ continue independently in
we can attempt to decipher the level of impact and personality displayed, whether or not to develop the mother's
In DZ twins, both womb wan,
environment has on an individual and the they grow up together, but even these and
foetuses will commonly on
influence genes have. As the genetics of the other lifestyle choices can vary dependant continue to develop opposite sides.
individuals would be Identical, we can say on environment. independently to
that differences displayed between two Ultimately, itishardtodrawfirm each other.
MZ twins are likely to be down to conclusions from twin studies as they will be
environmental influences. an unrepresentativelysmall sample within a
Some of the most Interesting studies look at much larger population and we often find that
twins that have been separated at birth, often both environment and genetics interact to
when individuals have been adopted by influence an individual's development.

171
 I
'ns and needles 1 Burns 1 Funny bones

What is 'pins
and les'?
The numb sensation ofyour leg
'going to sleep'lsn't caused by
cutting off the blood circulation.
It's the pressure on the nerves that
is responsible. This squeezes the Insulating
sheath around the nerve and 'shorts It out',
blocking nerve transm lsslon. When pressure
Is released, the nerves downstream from the
pinch point suddenly all begin firing at once.
Thisjumbleofunco-ordlnated signals Is a
mixture of pain and touch, hot and cold all
mixed together, which Is why It's excruciating.

"Thts squeezes the

insulating sheath
around tfle nerve
and 'shorts it out'"
~-
••
Why do
paper
cuts hurt
so much?
Paper can cut your skin
as it is incredibly thin
and, if you were to look
at it under a high-
powered microscope, it has
serrated edges. Critically though, a
sheet ofloose paper is far too soft
and flexible to exert enough
pressure to pierce the skin, hence
why they are not a more frequent
Are there other 'funny
occurrence. However, if the paper
is fixed in place- maybe by being
bones' in the body?
sandwiched within a pack of The term 'funny bone' is misleading
paper- a sheet can become stiff because It refers to the painful sensation
enough to attain skin-cutting youexpertencewhenyoutrapyourulnar
pressure. Paper cuts are so painful nerve between the skin and the bones of
once inflicted as they stimulate a the elbow joint.This happens In the so-called cubital
large number of pain receptors- tunnel, which directs the nerve 011erthe elbow but has
nociceptors send nerve signals to little padding to protect against external impacts. The
the spinal cord and brain-in a ulnar nerve takes Its name from the ulna bone, which is
very small area due to the oneoftwo bones that runs from thewrtstto the elbow;
razor-type incision. Because paper the other Is the radial bone, or radius.
cuts tend not to be deep, bleeding No other joint In the human skeleton combines these
is limited, leaving pain receptors conditions and duplicates the this erroneously named
open to the environment reaction so we only have one 'funny bone'.

172
 do our muscles ache?
Learn what causes stiffness and pain in our muscles for days after exercise
Normally, when our muscles contract
they shorten and bulge, much like a
Weightlifting and the body
bodybuilder's biceps. However, if the What happens to your biceps when you pump iron?
muscle happens to be stretched as it
Pain Bending
contracts it can cause microscopic damage. Thesorenessassoclated NormaJJywhen the bleeps
The quadriceps muscle group located on the with exercise Is the result muscle group oontracts it
of repetitive stretching of shortens, puJJlng the forearm
front of the thigh is involved in ex tending the oontracted muscles. towards the shoulder.
knee joint, and usua lly contracts and shortens to
s traighten the leg. However, when walking
down a steep slope, say, the quadriceps contract
to support your body weight as you step
forward, but as the knee bends, the muscles are
pulled in the opposite direction. This tension
resu lts in tiny tears in the muscle and this is the
reason that downhill running causes so much
delayed-onset pain.
At the microscopic level, a muscle is made up
of billions of stacked sarcomeres, containing
molecular ratchets that pull agaJnst one another
to generate mechanical force. If the muscle is
taut as it tries to contract. the sarcomeres get
pulled out of line, causing microscopic damage. Straightening ---' Stretching
The muscle becomes inflamed and fills with Astheannstraightensout. the As the muscle tries to
hlcepsarestretcbed, hut the cootract, theweight pulls in
fluid, causing stiffn ess and activating pain welghtisstlllpnllingdownon the opposite directiorl.
receptors- hence that achy feelIng you get after the band. so the muscles remain causing mlcroscoplc tears
unfamiliar exercise. part.Jyoontracted to support it within the muscle cells.
 Why do the Why shouldn't
we eat raw
upper arm
i meat?
and per Meat can harbour many different bacteria, viruses
and even parasites. Cooking meat properly

leg have only destroys them, making meat much safer for
consumption. Bacteria and viruses can make you
ill, while parasitescangrowinsideyour gut and even migrate

• one bone? to your brain. Food poisoning is a very serious business and
by not cook! ng meat thoroughly, you are greatly increasing
your chances of getting something nasty. People quite often
The makeup of the eat rawmeatsuch as steak tartare, but it requires extra care

t9 human skeleton is a
fantastic display of
• evolution that has left us
In the preparation. Besides safety; cooking meat also makes it
taste better. By cooking meat and other foods, humans can
get much more energy than from chewing raw food alone.
with the ability to perform
Incredibly complex tasks without
even thinking about them. There
are several different types ofjoint
between bones in your body, which
reflect their function; some are
strongandallowlittle movement,
others are weak but allow free
movement. The forearm and tower
leg have two bones, which form
plane joints at the wrist and ankle.
This type ofjointallows fora range
of fine movements, including gliding
and rotation. The hinge joints at
yourelbowsand knees allow for less
lateral movement, but they are
strong. Shoulders and hips, though,
are ball-and-socketjoints, which
allow for a wide range of motion.

How do
•
I
work?
The terms 'inoculation' and 'vaccination' are
used interchangeably. They involve
Introducing a foreign substance (antlgens) into
the body, causingantibodyproduction. These
caneltherbedead, made tess harmful, or just contain
certain bits that cause disease.
White blood cellscalied Blymphocytes recognise these
antigens, and produce antibodies to neutralise them.
After the initial encounter, a group of Blymphocytes are
made ca lied 'memory cells', which produce a ntlbodles
faster ifexposed to the same antigen again.

"They involve introducing

antigens into the body"

174
Why do we
develop gout?
Excessive levels of uric add In the blood
cause gout We producewicactdasa waste
product from digesting protein .Uricadd is
removed by the kidneys and excreted as a
dllutesolutlon.lfkldney function Is impaired, the
concentration rises to the point where it prectpltates as
monosodium urate crystals.
These normally form In the joints of yourtoes,
because your feet are cooler and cold temperatures
reduce the solubility of uric acid. Gout is partly genetic,
but exacerbated by excessive drinking - particularly
beer-and not enough exercise, so there are things
that can be done to help avoid suffering.

"Your feet ore cooler

ond cold temperatures
reduce the solubility
of uric ocid"

175
 --·
-=
--
- THE

HUMAN
=BOD¥ ~=

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 ~CURIOUS QUESTIONS

The circulation
system

BOOK OF I
Human

THE respiration

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combat viruses?

The development
of an embryo

How do we
smell? I

,..__ ~

• •

0
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--
The science .._•
behinda -
sprained ankle
...:,.• .·..••••
"•

Human anatomy
Discover how our hearts beat, our I
•••
..
I • ••• ....
..•
•t
.:
The science •
brains think and our ears hear and of genetics The structure
everything in between of the skeleton
Functions
of the liver

/ ...
·e.
--

The The body at work Curious questions

importance Uncover amazing acts that explain some of
find out how our bodies work, from
ofteeth \
genetics and the immune system to We's biggest questions, such as what
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Inside the eye