28.
1 Levels of Organization
KEY CONCEPT
The human body has five levels of organization.
28.1 Levels of Organization
Specialized cells develop from a single zygote.
• Organisms are made up of specialized cells.
red blood cell nerve cell
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28.1 Levels of Organization
• Zygotes first divide into embryonic stem cells.
• Stem cells develop in
two stages.
– determination, or
committing to
become one cell type
– differentiation, or
acquiring specialized
structures and
functions
28.1 Levels of Organization
Specialized cells function together in tissues, organs,
organ systems, and the whole organism.
• Specialized cells perform specific tasks.
• Tissues are groups of similar cells working together.
– epithelial tissue
– connective tissue
– muscle tissue
– nervous tissue
cell
tissue
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28.1 Levels of Organization
• Organs are different tissues working together.
• Organ systems are two or more organs working together.
• Organism is all organ systems working together.
ORGANS
ORGAN SYSTEM
ORGANISM
28.1 Levels of Organization
• There are 11 major organ systems in the human body.
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28.2 Mechanisms of Homeostasis
KEY CONCEPT
Homeostasis is the regulation and maintenance of the
internal environment.
28.2 Mechanisms of Homeostasis
Conditions within the body must remain within a narrow
range.
• Homeostasis involves keeping the internal environment
within set ranges.
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28.2 Mechanisms of Homeostasis
• Control systems help maintain homeostasis.
– sensors gather data
pore
– control center receives
data, sends messages sweat
glands
– communication system
delivers messages to
target organs, tissues hair
follicle
– targets respond to change muscle
goose
bump
28.2 Mechanisms of Homeostasis
Negative feedback loops are necessary for homeostasis.
• Feedback compares current conditions to set ranges.
• Negative feedback counteracts change.
Negative Feedback Loop
Holding breath, CO2
levels rise,
O2 / CO2 level returns to
normal
Control system forces
exhale, inhale
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28.2 Mechanisms of Homeostasis
• Positive feedback increases change.
– Torn vessel stimulates release of clotting factors
platelets blood vessel
fibrin
clot
white blood cell
red blood cell
– growth hormones stimulate cell division
28.3 Interactions Among Systems
KEY CONCEPT
Systems interact to maintain homeostasis.
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28.3 Interactions Among Systems
Each organ system affects other organ systems.
• An organ system must do a specific job.
• Organ systems must also work together to keep the
organism healthy.
28.3 Interactions Among Systems
• Organ systems must also work together to keep the
organism healthy.
– Organ systems work together to produce Vitamin D.
– Thermoregulation maintains a steady body temperature.
UV light
1 Skin absorbs UV light
2 Liver produces inactive vitamin D
3 Kidneys produce active vitamin D 4 Active vitamin D used in bones
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28.3 Interactions Among Systems
A disruption of homeostasis can be harmful.
• Homeostasis can be disrupted for several reasons.
– sensors fail
– targets do not receive messages
– injury
– illness
28.3 Interactions Among Systems
• Short-term disruption usually causes little or no harm.
• Long-term disruptions can cause more damage.
• Diabetes is a serious long-term disruption of homeostasis.
pancreas
1 Pancreas cells attacked;insulin
declines
fats
2 Blood glucose levels rise,
kidneys
3 Body burns fat; blood more acidic, 4 Cells impaired; all organs
damaged.
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30.1 Respiratory and Circulatory Functions
KEY CONCEPT
The respiratory and circulatory systems bring oxygen
and nutrients to the cells.
30.1 Respiratory and Circulatory Functions
The respiratory and circulatory systems work together to
maintain homeostasis.
• The circulatory system transports
blood and other materials. Oxygen-poor blood
– brings supplies to cells
– carries away wastes
– separates oxygen-poor and
oxygen-rich blood
Oxygen-rich blood
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30.1 Respiratory and Circulatory Functions
• The respiratory system is where gas exchange occurs.
– picks up oxygen from inhaled air
– expels carbon dioxide and water
sinus
nose
mouth
epiglottis
trachea
lungs
30.1 Respiratory and Circulatory Functions
The respiratory system moves gases into and out of the
blood.
• The lungs contain the bronchi, bronchioles, and alveoli.
• Millions of alveoli give the lungs a huge surface area.
• The alveoli absorb oxygen from the air you inhale.
alveoli
bronchiole
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30.1 Respiratory and Circulatory Functions
• Breathing involves the diaphragm and muscles of the rib
cage.
• Air flows from areas of high pressure to low pressure.
Air inhaled. Air exhaled.
Muscles and
rib cage relax.
Muscles contract and
rib cage expands.
Diaphragm flattens Diaphragm relaxes
and moves downward. and rises.
30.1 Respiratory and Circulatory Functions
The circulatory system moves blood to all parts of the
body.
• The system includes the heart,
veins
arteries, veins, and capillaries.
– heart pumps blood throughout body
– arteries move blood away from
heart
– veins move blood back to heart
– capillaries get blood to and from
cells
arteries
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30.1 Respiratory and Circulatory Functions
• There are three major functions of the circulatory system.
– transporting blood, gases, nutrients
– collecting waste materials
– maintaining body temperature
30.2 Respiration and Gas Exchange
KEY CONCEPT
The respiratory system exchanges oxygen and carbon
dioxide.
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30.2 Respiration and Gas Exchange
Gas exchange occurs in the alveoli of the lungs.
• Oxygen and carbon dioxide are carried by the blood to and
from the alveoli.
– oxygen diffuses from alveoli into capillary
– oxygen binds to hemoglobin in red blood cells
– carbon dioxide difuses from capillary into alveoli
ALVEOLI GAS EXCHANGES
capillary
alveolus
Co2 diffuses
into alveolus. co2
o2 O2 diffuses
into blood.
capillaries
30.2 Respiration and Gas Exchange
Gas exchange occurs in the alveoli of the lungs.
• Breathing is regulated by the brain stem.
midbrain
pons
medulla
oblongata
spinal chord
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30.2 Respiration and Gas Exchange
Respiratory diseases interfere with gas exchange.
• Lung diseases reduce airflow and oxygen absorption.
– Emphysema destroys alveoli.
– Asthma constricts airways.
– Cystic fibrosis produces sticky mucus.
30.2 Respiration and Gas Exchange
• Smoking is the leading cause of lung diseases.
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30.3 The Heart and Circulation
KEY CONCEPT
The heart is a muscular pump that moves the blood
through two pathways.
30.3 The Heart and Circulation
The tissues and structures of the heart make it an
efficient pump.
• Cardiac muscle tissue works continuously without tiring.
NORMAL HUMAN HEART
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30.3 The Heart and Circulation
• The heart has four chambers: two atria, two ventricles.
• Valves in each chamber prevent backflow of blood.
pulmonary valve
aortic valve
left atrium
right atrium
mitral valve
left ventricle
tricuspid
right ventricle septum
• Muscles squeeze the chambers in a powerful pumping
action.
30.3 The Heart and Circulation
• The heartbeat consists of two contractions.
– SA node, or pacemaker, stimulates atria to contract
– AV node stimulates ventricles to contract
SA node
VA node
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30.3 The Heart and Circulation
• Blood flows through the heart in a specific pathway.
1 3
2 4
30.3 The Heart and Circulation
• Blood flows through the heart in a specific pathway.
– oxygen-poor blood enters right atrium, then right
ventricle
– right ventricle pumps blood to lungs
– oxygen-rich blood from lungs enters left atrium, then left
ventricle
– left ventricle pumps blood to body
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30.3 The Heart and Circulation
The heart pumps blood through two main pathways.
• Pulmonary circulation occurs between the heart and the
lungs.
– oxygen-poor blood enters lungs
– excess carbon dioxide and water
expelled
– blood picks up oxygen
– oxygen-rich blood returns to heart
30.3 The Heart and Circulation
• Systemic circulation occurs between the heart and the rest
of the body.
– oxygen-rich blood goes to organs,
extremities
– oxygen-poor blood returns to
heart
• The two pathways help maintain a
stable body temperature.
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30.4 Blood Vessels and Transport
KEY CONCEPT
The circulatory system transports materials
throughout the body.
30.4 Blood Vessels and Transport
Arteries, veins, and capillaries transport blood to all parts
of the body.
• Arteries carry blood away from the heart.
– blood under great pressure
– thicker, more muscular walls
endothelium
smooth muscle
valve
connective tissue
ARTERY
VEIN
CAPILLARIES
arteriole venule
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30.4 Blood Vessels and Transport
• Veins carry blood back to the heart.
– blood under less pressure
– thinner walls, larger diameter
– valves prevent backflow
endothelium
smooth muscle
valve
connective tissue
ARTERY
VEIN
CAPILLARIES
arteriole venule
30.4 Blood Vessels and Transport
• Capillaries move blood between veins, arteries, and cells.
endothelium
smooth muscle
valve
connective tissue
ARTERY
VEIN
CAPILLARIES
arteriole venule
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30.4 Blood Vessels and Transport
• Blood pressure is a measure of the force of blood pushing
against artery walls.
– systolic pressure:
left ventricle
contracts
– diastolic pressure:
left ventricle
relaxes
• High blood pressure can precede a heart attack or stroke.
30.4 Blood Vessels and Transport
Lifestyle plays a key role in circulatory diseases.
• Some choices lead to an increased risk of circulatory
diseases.
– smoking
– long-term stress
– excessive weight
– lack of exercise
– diet low in fruits
and vegetables,
high in saturated
fats
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30.4 Blood Vessels and Transport
• Circulatory diseases affect mainly the heart and the
arteries.
– artery walls become thick and inflexible
– plaque blocks blood flow in arteries
30.5 Blood
KEY CONCEPT
Blood is a complex tissue that transports materials.
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30.5 Blood
Blood is composed mainly of cells, cell fragments, and
plasma.
• Whole blood is made up of different materials.
– plasma
– red blood cells
– white blood cells
– platelets
plasma
red blood cells,
white blood cells,
and platelets
30.5 Blood
• Plasma is a key factor in maintaining homeostasis.
– molecules diffuse into and out of plasma
– contains proteins that stabilize blood volume
– contains clotting factors
– contains immune proteins
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30.5 Blood
Platelets and different types of blood cells have different
functions.
• The bone marrow manufactures most of the blood
components.
red blood cell
platelet
white blood cell
30.5 Blood
• Red blood cells make up 40-45 % of all blood cells.
– transport oxygen to cells and carry away carbon dioxide
– have no nuclei and contain hemoglobin
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30.5 Blood
• White blood cells fight pathogens and destroy foreign
matter.
red blood cell
platelet
white blood cell
30.5 Blood
• Protein markers define blood types and Rh factors.
– ABO blood group the most common
– Rh factor can be negative or positive
– blood types must be compatible for transfusions
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30.5 Blood
• Platelets help form clots that control bleeding.
platelets
fibrin
white
blood cell
red blood cell
30.6 Lymphatic System
KEY CONCEPT
The lymphatic system provides another type of
circulation in the body.
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30.6 Lymphatic System
Lymph is collected from tissues and returned to the
circulatory system.
• The lymphatic system collects fluid
that leaks out of the capillaries. heart
– Lymph vessels have valves to
prevent backflow.
– Lymph nodes filter the lymph
and destroy foreign matter. lymph nodes
– Lymph vessels return cleaned
fluid to the circulatory system. lymph vessels
• If lymph vessels or nodes are
damaged, lymph collects in an
area.
30.6 Lymphatic System
The lymphatic system is a major part of the immune
system.
tonsils
• Structures in the lymphatic
system help fight disease. thymus
– tonsils filter bacteria
spleen
and viruses
– thymus develops white
blood cells
– spleen filters lymph,
contains immune cells
• Lymphocytes help destroy pathogens, parasites,
and foreign matter.
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