Respiration

Respiration is the process by which food material is oxidized to give energy by all living cells.
(The process by which energy is released from food in all living cell)

This process is catalyzed by enzymes and occurs slowly in a large number of stages.
It is sometimes called cellular or tissue respiration. The process can be summarized like this,
TYPES OF RESPIRATION
There are two types of respiration:
1. Aerobic Respiration
2. Anaerobic Respiration
AEROBIC RESPIRATION
This involves the use of oxygen to oxidize chemicals e.g. Glucose and occur in the mitochondria of cells.
It always produces carbon dioxide, water and about 38 ATP molecules per molecule of glucose. This type
of respiration will produce 18 times more energy than anaerobic respiration. A great deal of heat energy
is released. The reactions are controlled by enzymes and the energy is released gradually in small
quantities.
MOLECULAR FORMULA FOR AEROBIC RESPIRATION
enzyme in
C6H12O6 + 6O2 6CO2 + 6H2O + 2830 Kilojoules (energy)
mitochondria
Most of the energy released at each stage is used to build energy carrying molecules called adenosine
triphosphate or ATP. An ATP molecule is formed by combining some of the energy released with an
adenosine diphosphate or ADP molecule and a phosphate group present in the cell. The energy can then
be re-released wherever it is needed in the cell by the reverse reaction:

ATP is known as the ‘energy currency’ of cells. Cells earn ATP as a result of energy-producing reactions
and spend it on reactions requiring energy. Energy released by ATP is used by cells to do daily activities
such as:
1. Contraction of the muscles
2. Cell division
3. For cell growth and repair.
4. In active transport to move molecules and ions in and out of the cells through their membranes.
1
 5. To manufacture complex, biologically important molecules, e.g. proteins, DNA.
6. Transmission of impulses in nerve cells.
7. Digestion
8. Breathing
9. Some of the energy is released as heat and this helps to maintain the body temperature at 37 °C.

Carbon dioxide is released as waste product and is excreted from the tissue cells. These excretory
products diffuse into the blood and are carried away. Carbon dioxide is finally excreted from the lungs, in
expired air saturated with water vapor. Water is taken from the alveoli.
Carbon dioxide when present reacts with water forming carbonic acid causing the pH of the blood
and tissue fluid to be lowered, which then affects the rate at which chemical reactions can occur within
cells (blood and tissue fluid pH 7.4).

ANAEROBIC RESPIRATION
This does not need oxygen. In this type of respiration, the food eg. Carbohydrates are not broken
down completely to carbon dioxide and water but to lactic acid or alcohol. This takes place in the
cytoplasm of some cells. The incomplete breakdown of the food means that less energy is released (2
ATP) in anaerobic respiration than in aerobic respiration. This is why some organism such as yeasts and
bacteria can survive where there is no oxygen.
Yeast cells carrying out this type of respiration are called fermentation – this action is utilized by
makers of wine and spirits to distill rum, wine and whiskey. Some of the cells in your body, particularly
muscle cells can also respire anaerobically for a short time. This takes place in the cytoplasm of the cells.
They make lactic acid instead of alcohol.
This usually occurs during strenuous exercise (vigorous activity) when the oxygen supply may not
be sufficient to completely oxidize the food required to meet the energy demands of the body.
MOLECULAR FORMULA FOR ANAEROBIC RESPIRATION

Enzyme in
C6 H12 O6 2C3 H6 O3 + 7KJ (very little energy) 2 ATP
Cytoplasm (Lactic Acid)

Enzyme in
C6 H12 O6 2 CO2 + 2C2 H5 OH + 118KJ (energy)
Cytoplasm (alcohol)
Oxidation of food material in the absence of oxygen builds up an Oxygen debt in the muscle which must
be repaid by resting so that the lactic acid can be converted aerobically to carbon dioxide and water.

OXYGEN DEBT
Muscle cells can carry out anaerobic respiration during strenuous exercise. During strenuous exercise, if
oxygen cannot be delivered to the muscle cells quickly enough for the demands of aerobic respiration, the
cells begin to respire anaerobically. This produces lactic acid and 2 ATP molecules per molecule of
glucose.

Enzyme in
Glucose Lactic + Acid Energy
Cytoplasm

Lactic acid builds up in the muscle cells and begins to harm them, causing fatigue, cramps and eventually
collapse as they stop contracting. The muscle cells are said to have built up an oxygen debt. This debt

2
must be repaid directly after exercise by resting and breathing deeply so that the lactic acid can be
removed by respiring it aerobically.

This is why athletes need to rest after exercise as breathing rate increases after exercise. Lactic acid harms
muscles if allowed to build up inside them causing fatigue, cramps, and collapse.

A COMPARISON OF AEROBIC AND ANAEROBIC RESPIRATION

SIMILARITIES
1. Energy released by breakdown of sugar.
2. ATP made
3. Some energy lost as heat.

DIFFERENCES BETWEEN AEROBIC AND ANAEROBIC RESPIRATION.

Aerobic Anaerobic

1. Uses oxygen 1. Does not use oxygen.

2. No alcohol or lactic acid made 2. Alcohol or lactic acid made.
3. Large amount of energy released 3. A small amount of energy is released.
38 ATP 2 ATP
4. Carbon dioxide always made 4. Carbon dioxide is sometimes made.
5. Occurs in the mitochondria 5. Occurs in the cytoplasm.

INDUSTRIAL AND DOMESTIC USES OF ANAEROBIC RESPIRATION

MAKING BREAD AND ALCOHOLIC BEVERAGES

Yeast cells carry out anaerobic respiration known as fermentation. It produces ethanol, carbon dioxide
and 2 ATP molecules per molecule of glucose.

Enzyme in
C6 H12 O6 2 CO2 + 2C2 H5 OH + 118KJ (energy)
Cytoplasm (alcohol)

BREAD MAKING
When making bread, flour is mixed with water to make dough. Flour contains starch and some of this
breaks down to the sugar maltose when the flour is moistened. Yeast is added to the dough and breaks
down the sugar as it respires aerobically at first, until the oxygen is used up. It releases carbon dioxide and
bubbles of this gas get caught in the dough making it rise. The yeast is killed when the bread is cooked.
When baked, heat from the oven causes the bubbles to expand, kills the yeast and evaporates the ethanol.

BREWING AND RUM MAKING

When making alcoholic beverages such as beer, wine, rum and other spirits, the yeast ferments sugars
present in grains, fruits or molasses. The yeast respires, breaking down the maltose and making alcohol
and carbon dioxide. The carbon dioxide makes the beer fizzy. Rum is made in a similar way, but the
sugar comes from cane juice or molasses.

3
Fermentation stops when the ethanol concentration reaches about 14–16% because it kills yeast cells, so
the ethanol content of beer and wine is always below about 16%. Spirits are made by distillation of the
fermentation mixture.
MAKING YOGHURT

Certain bacteria, e.g. Lactobacillus, ferment the lactose in milk forming lactic acid. The lactic acid makes
the milk proteins curdle, which forms thick yoghurt and gives the yoghurt its sour taste.

BACTERIAL FERMENTATION
Certain bacteria are used to break down organic matter, e.g. manure and garden waste, anaerobically in an
anaerobic digester. This produces biogas which is a mixture of approximately 60% methane (CH 4), 40%
carbon dioxide and traces of other gases, e.g. hydrogen sulfide (H 2S). Biogas can be used as a fuel for
cooking, heating and to generate electricity.

RESPIRATION IN MAN

All living organisms need energy to carry out life processes in order to survive. They obtain this energy
from food when the food is respired. Humans respire aerobically and their respiratory system is
responsible for taking in the oxygen they need to sustain this respiration and to constantly get rid of the
carbon dioxide they produce.

BREATHING AND GASEOUS EXCHANGE

Breathing refers to the movements that cause air to be moved into and out of the lungs. Breathing must
not be confused with respiration, which is the process by which energy is released from food by all living
cells.
STRUCTURE OF THE HUMAN RESPIRATORY SYSTEM
Breathing begins with the intake of air rich in oxygen through the nose into the nasal passages. These
passages lie between bones of the skull and are lined with mucus membrane. They are separated from the
mouth by a boney structure, the palate (hard and soft palate). The nasal passages lead into the pharynx
(throat).

4
The pharynx, a passageway for both air and food, into the larynx and esophagus, extends from the base of
the skull to the level of the sixth cervical vertebrate. It is wider at its upper end. The air is further warmed
and moistened as it passes through the pharynx. Air can also be drawn through the mouth.

Mouth breathing does not moisten the air sufficiently and in addition there is no filtering mechanism to
remove dust. The pharynx leads into the larynx.

The larynx or voice box extends from the root of the tongue to the trachea. Until puberty there is little
difference in the size of the larynx between the sexes. There after it grow larger in males which explain
the prominence of the “Adam apple” and generally have deeper voice. The vocal cords can be tightened
by muscle so that they make sounds when air passes over them.

FUNCTIONS OF THE LARYNX

a) The larynx provides a passageway for air between the pharynx and the trachea. As air from
outside passes through it, it is further moistened, filter and warm thus continuing the process
started.
b) The vocal cord provides sounds of varying loudness and pitch.
c) During swallowing the larynx moves upward closing the opening into it from the pharynx. This
ensures that food passes into the oesophagus and not into the lower respiratory passage.

At the top of the trachea just above the larynx is a piece of cartilage called the epiglottis; this closes the
trachea and stops food going down the trachea when you swallow. This is a reflex action which happens
automatically when a bolus of food touches the soft palate.
The larynx is continuous with the trachea, which is situated in front of the oesaphagus. This is a muscular,
cylindrical tube consisting of “C” shaped rings of cartilage which prevents it from collapsing. It extends
into the thorax where it divides into two (2). The two branches are called the right and left bronchi. One
bronchus goes to each lung. The right bronchi are wider and shorter than the left. The whole track from
the nose to the end of the bronchi is lined with hair-like processes called cilia.

5
In each Lung the bronchus divides repeatedly into smaller tubes called bronchioles and each becoming
smaller and smaller. At the end of each bronchiole are many tiny air sacs or alveoli (this is where gaseous
exchange takes place). Each alveolus is surrounded by a network of blood capillaries.
Blood is supplied to the capillaries by the pulmonary artery and taken from them by the pulmonary vein.
The whole track starting from the nose provides a passage for atmospheric air rich in oxygen to be
conducted to the alveoli.

The two lungs are surrounded by the ribs which form the chest cavity or thorax. The ribs have intercostal
muscles between and a dome-shaped sheet of muscle, the diaphragm, stretches across the floor of the
thorax.
FUNCTION OF THE AIR PASSAGE
1) The cartilage (c shaped) in the larger air passage keeps them open, allowing for the unobstructed
passage of air between the outside atmosphere and the alveoli of the lungs. The cartilage is ‘c’
shaped (it does not extend to the back of the trachea) so as to reduce friction with the oesaphagus.
2) The mucus which coats the lining membrane is of a sticky consistency to which particles in the air
adhere (stick), preventing them from reaching the alveoli.
3) The waves like motion of the cilia of the lining membrane sweep the mucus and adherent particles
towards the throat. When it reaches the pharynx, it is usually swallow but it maybe expectorated
(brought up from the lungs). (The process maybe aided by coughing).
4) The diameter of the respiratory passage maybe altered by contraction or relaxation of the
involuntary muscle in their walls, thus regulating the volume of the air entering the lungs.
5) Inhaled air not saturated with water vapour take up moisture from the surface mucus. Inhalation of
dry air over a period of time causes irritation of mucosa and facilitates the entry of pathogenic
microbes.
6) Expired air is warm (or cool) to body temperature by contact with the walls of the air passage.

THE LUNGS
There are two lungs conical in shape one lining on each side of the mid-line of the thoracic cavity. They
are described as having an apex, a base, costal surface and medical surfaces.

The apex is rounded and rises into the root of the neck about 25mm (1inch) above the level of the middle
third of the clavicle. The base is concave and is resting on the upper surface of the diaphragm.
The right lung is divided into three (3) distinct lobes, the left lung is divided into two:
They are pink in colour and composed of spongy tissue. It is covered by a membrane, the pleura. Pleura is
a double membrane and forms a close sac (one for each lung) with a pleural cavity between the
membranes. The inner surfaces of the sac are moistened by pleural fluid which allows the membrane to
slide over each other when the chest moves and so it provides lubrication for the movement.

MECHANISM OF BREATHING
The thorax, except for the entrance through the trachea forms an airtight cavity called the thoracic
cavity. The cavity is formed by the ribs and the diaphragm. The ribs are attached to the backbone at one
end and to the sternum (breastbone) to the front. The ribs are connected to each other by two sets of
intercostals muscles (one set of muscles contract and the ribcage are raised upward and outward. This rib
action is to increase the volume of the lungs).
6
 The diaphragm is a dome – shaped sheet of fibrous muscle tissue. When the diaphragm contracts,
it flattens. Lowering the diaphragm increases the volume of the thoracic cavity and thus reduces its
pressure, atmospheric pressure being now greater forces air into the lungs.
The action of the ribs in increasing the volume of the thoracic cavity causes air to be forced into the lungs.
These two mechanisms of breathing, i.e. using the ribs and diaphragm, take place at the same time
(simultaneously).
Increasing the volume of the thoracic cavity (and decreasing its pressure) is called inspiration.
Decreasing the volume of the thoracic cavity (and increasing its pressure) is called expiration. Inhalation
and the expiration of air is called breathing.

Demonstration of Breathing Mechanism

Take a bell jar. Towards its rounded end, fix a 'Y' shaped glass tube and on the open ends of the two
branches tie a balloon each. On its open end tie a thin rubber sheet. The cavity of the bell jar acts as the
thoracic cavity, the "Y" shaped tube as the trachea that branches into bronchi and the rubber sheet as the
diaphragm.

7
A. The bell jar apparatus above represents a model to illustrate the working of the structures
concerned with breathing.
B. Pull the rubber sheet down and the balloon inflates (blow up).
C. Push it up and the balloon deflates (air out).

The dotted lines represent the position at expiration (breathing out) when the rubber diaphragm moves
upward. The bold lines show the position at inspiration (breathing in).
FACTORS AFFECTING THE BREATHING RATE
The normal breathing rate for a healthy adult at rest ranges from 12 to 16 breaths per minute. The medulla
of the brain controls the breathing rate by detecting the level of carbon dioxide in the blood and sending
impulses to the intercostal muscles and diaphragm.

• Any factor that increases the rate of respiration in body cells will cause the level of carbon dioxide in the
blood to increase. If carbon dioxide levels increase, breathing rate increases to remove the excess carbon
dioxide. Factors that increase breathing rate include:
- Carrying out exercise.
- Taking drugs that are stimulants, e.g. caffeine, amphetamines, cocaine.
- Smoking cigarettes.
- Suffering from anxiety or fear.
- Being exposed to certain environmental factors, e.g. being in a confined space or in polluted air.
- Being at high altitude.

8
 - Being overweight.
• Any factor that decreases the rate of respiration in body cells will cause the level of carbon dioxide in the
blood to decrease. If carbon dioxide levels decrease, breathing rate decreases. Factors that decrease
breathing rate include:
- When resting or asleep. Taking drugs that are depressants, e.g. sedatives, sleeping pills, alcohol.
- Being exposed to certain environmental factors, e.g. being in fresh, unpolluted air.

VITAL CAPACITY

Vital capacity is the maximum volume of air that can be exhaled from the lungs after inhaling as deeply as
possible. Measuring vital capacity can be used to indicate lung function and if a person is suffering from
lung disease. Vital capacity depends on age, gender, body size and fitness. It can be increased by regular
exercise and is decreased by smoking, obesity or respiratory disease.

ACTION OF BREATHING
Normal breathing is involuntary. (The normal rate of breathing is amount 18 times per minute).
However, breathing can be control. The volume of air entering and leaving the lungs during normal
breathing is called “tidal wave”.
The lungs are not completely empty at each breath. The increase in volume to completely fill the lungs is
called “complemental air” (inspiratory reserve). The decrease in volume to empty the lungs by “force”
expiration is called “supplemental air” (expiratory reserve). The largest change of volume that the lungs
are capable of making is called vital capacity (complemental air + supplemental air). This volume is
about 4.0 liters (1 gallon). Even with deep breathing the lungs are not completely empty, the remaining
air left in the lungs is called residual air. It is never expelled from the lungs. The volume of residual air
is 1000cm3 (1.2 liters)

Aim: To investigate the capacity of the lungs.

Apparatus: Spirometer, water, rubber, tube, glass tube.

9
Method: First invert the bell jar and pour in water 1000
cm3 at a time and mark the levels with a chinograph pencil.
Fill the jar with water and turn it over the sink full of water and place it on supports
to allow space for the movement of water. Air expired from the lungs, through the
mouth placed over the tubing, will displace water.

a) The vital capacity is found by breathing in and blowing out as much air as you can into the
apparatus.
b) The tidal air is found by breathing out the amount you would normally expire during quiet
breathing.
c) The inspiratory reserve can be found by subtracting the tidal and expiratory reserve from the vital
capacity.

EXCHANGE OF GASES
Some of the Oxygen in the air taken in (inspiration) dissolves in the moisture of the walls of the alveoli.
The dissolved oxygen diffuses through the thin membrane of the alveoli, then through the walls of the
blood capillaries into the blood onto the red blood cell.

On the membrane of the red blood cells is a chemical substance, called haemoglobin. This substance
gives blood its red colouration. Haemoglobin combines with oxygen to form a chemical compound called
oxyhaemoglobin and removes the dissolved oxygen. The oxygen is then transported by the blood via
pulmonary veins, to the left side of the heart and from there it is pumped to the tissue of the body.

10
During the oxidation of food material to give energy, carbon dioxide is produced as a bi- product (aerobic
respiration). This is then passed into the blood from the tissue and is transported as sodium hydrogen
carbonate (carbon dioxide combines with water to form carbonic acid. Carbonic acid combines with
sodium and potassium to form sodium hydrogen carbonate (NaHCO3) and potassium hydrogen carbonate
(KHCO3). These compounds are broken down in the lungs to release carbon dioxide (CO2) to the lungs.
In the capillaries surrounding the villi, this carbon dioxide diffuses through the capillary walls, then
through the walls of the villi and is swept out of the lungs during expiration. A diffusion gradient exists
between the alveoli and the blood in the capillaries for both gases.

The concentration of oxygen in the blood is lower than that in the alveoli, therefore oxygen will diffuse
from a region of high concentration (in the alveoli) into the blood, onto the red blood cells where the
concert ration is lower.
At the same time the concentration of carbon dioxide in the blood is greater than that in the alveoli
therefore, carbon dioxide will leave the region of high concentration in the alveoli. Hence, diffusion takes
place to attempt to equalize the concentration.

FEATURES OF THE WALL OF THE ALVEOLUS THAT HELP TO INCREASE THE RATE OF DIFFUSION OF GASES
INTO AND OUT OF THE BLOOD

1. A large surface area – large amount of gas can be exchange.

2. They are thin – (one cell thick) – gases can diffuse across rapidly.
3. Moist – (film of moisture) – gases must be dissolved before they can diffuse through the surface.
4. Rich blood supply – capillaries around the alveoli carries gases rapidly between the surface and
body cells.

PS. Breathing and gaseous exchange are essential to organism respiring aerobically to ensure that
they have a continuous supply of oxygen and a means of continuous removal of carbon dioxide which
if left to accumulate would poison the cell.

11
PERCENTAGE VOLUME

INSPIRED OR
GASES ATMOSPHERIC AIR EXPIRED AIR

OXYGEN 21% 16%

CARBONDIOXIDE 0.03% 4%

NITROGEN 78% 78%

OTHER GASES 1% 1%

WATER VARIABLE ALWAYS HIGH

TEMPERATURE VARIABLE ALWAYS HIGHER

ARTIFICIAL RESPIRATION

MOUTH TO MOUTH RESUSCITATION

If a person has an accident example drowning, electric shock or motor vehicle, he may go
unconscious and stop breathing. Sometimes it is possible to keep the person alive by giving artificial
respiration in an attempt to start the breathing again. One of the best methods is mouth to mouth
resuscitation. This must be carried out as soon as possible otherwise the brain cells may be damage.
PROCEDURE
1. Tilt the casualty’s head back and the chin upwards, this is to open the airway.
2. Pinch the nostrils shut with the fingers of one hand and push the lower jaw down.
3. Take a deep breath, then open your mouth and seal your lips against the person’s mouth. Breathe
out firmly but gently into the person’s mouth and so into his lungs (watch his chest rise).
4. Lift your mouth off, and then turn your head so as to look at the person’s chest. If you have been
successful, you will see that it has risen and is now fallen as air comes out of the lungs.
5. Repeat at a ready rate at about ten breaths per minute. The person colour should improve on
eventually he should start breathing for himself.
6. When breathing starts, place him on his side. Keep his health tilt with his jaw open to maintain the
open airway.

PS. Check for a pulse after every tenth breaths.

12
EFFECT OF MOUTH TO MOUTH RESUSCITATION
Because the expired air blown into the mouth of the casualty’s contains some 4-6 percent carbon
dioxide, the medulla region of the brain is stimulated to initiate breathing. The 16 percent of oxygen in
the expired air will be enough to nearly saturate the blood in the lungs and aid recovery.

REASON FOR DIFFERENCES BETWEEN INHALE AND EXHALE AIR

Oxygen is absorbs across respiratory surface, and then used by the cell’s inspiration. Carbon
dioxide is made b cells as a waste product of respiration and is released across the respiratory surface
(gaseous exchange).

Nitrogen – gas is not used by cells

Water – respiratory surface must be kept moist. Some of the moisture evaporates and is lost as air is
breathed out.
Temperature – air is warmed as it passes through the respiratory passages.

BREATHING AND EXERCISE

Exercise increases the breathing rat and more of the complemental and supplemental reserve
volumes of air is used up. The rate of breathing is controlled automatically by the medulla region of the
brain. When the carbon dioxide concentration of the blood increases, example during exercise the
breathing movements becomes first deeper and then faster. Chemoreceptors in the carotid arteries detect
the impulses to the respiratory centre of the medulla which in turn causes an increase in the breathing rate.
The increased breathing rate will supply more oxygen to release energy for activity and remove the carbon
dioxide. As the carbon dioxide concentration is reduced breathing rate will decrease. This is an example
of homeostasis.

13
SMOKING AND HEALTH

There is statistical and experimental evidence to associate smoking with the incident of lung
cancer and coronary heart attack. Heavy smokers suffer persistent cough which damage the lungs and
increases susceptibility (prone) to bronchitis and pneumonia. Carbon monoxide (CO) in tobacco smoke
combines with haemoglobin in the blood of smoker. Increasing the permeability of their blood vessel and
this in turn leads to a high rate of the deposition of fat in the artery lining and an increased risk of coronary
heart attack. Giving up smoking will progressively reduce the above.

14
THE EFFECTS OF CIGARETTE SMOKE

Smoke content Main physiological effect Symptoms

Tars Cause cancer of lungs and Cancer

mouth
Carcinogens are cancer
producing substances e.g. tar
Carbon monoxide Combines with blood Shortness of breath
hemoglobin and reduces the Damages heart muscle
oxygen-carrying capacity
Particles and vapor with Stop cilia sweeping out mucus Phlegm accumulates
chemicals from bronchiole tubes Bronchitis- Inflammation of
Bronchiole tubes constrict air tubes cause coughing
Emphysema-Alveoli walls
damaged, enlarged air spaces
Nicotine Causes addiction Reduce stress
Affects neurotransmitter Stimulant
substances Raise blood pressure
Adrenaline released from Artery Walls thicken and
glands harden
Blood Platelets adhere Heart attacks caused
Fatty acids increase in blood Reduced urine
Increased ADH secretion

THE DANGERS OF TOBACCO SMOKING

The diseases cancer, bronchitis, emphysema, heart attacks and shortness of breath are far more common
among smokers.

One in five deaths are attributed to smoking in some countries. Heavy cigarette smokers are 30 times more
likely to die from lung cancer than non-smokers.

Women who smoke have more abortions (fetus dies), stillbirths (baby born dead) and premature births
(baby born early) than non-smoking mothers.

Lung damage
Cigarette smoke damages lungs:
• It causes mucus production to increase and it paralyses the cilia, which stops them from beating so the
mucus is not removed. The person then develops a persistent cough to try and remove the mucus.
• It irritates and inflames the walls of the bronchi and bronchioles. This, together with the increased mucus
production and paralysis of the cilia, causes the airways to become obstructed, making breathing difficult,
and leads to chronic bronchitis.
• It causes the walls of the alveoli to become less elastic and the walls between the alveoli to break down,
which decreases their surface area. This reduces gaseous exchange, makes exhaling difficult and causes
air to remain trapped in the lungs, a condition known as emphysema. The bronchioles often collapse when
exhaling, obstructing the airways, making exhaling even harder.

15
CANCER OF THE MOUTH, THROAT, OESOPHAGUS OR LUNGS

Some components of tar and many other chemicals in cigarette smoke are carcinogenic. These cause
mutations in cells in different regions of the respiratory system. This leads to the development of
cancerous tumours which replace normal, healthy tissue in these regions. Note that chronic bronchitis and
emphysema are two types of chronic obstructive pulmonary disease or COPD.

TOBACCO USE AND PREGNANCY | REPRODUCTIVE HEALTH

How Does Smoking During Pregnancy Harm My Health and My Baby?

Most people know that smoking causes cancer, heart disease, and other major health problems. Smoking
during pregnancy causes additional health problems, including premature birth (being born too early),
certain birth defects, and infant death.

• Smoking makes it harder for a woman to get pregnant.

• Women who smoke during pregnancy are more likely than other women to have a miscarriage.
• Smoking can cause problems with the placenta - the source of the baby's food and oxygen during
pregnancy. For example, the placenta can separate from the womb too early, causing bleeding,
which is dangerous to the mother and baby.
• Smoking during pregnancy can cause a baby to be born too early or to have low birth weight-
making it more likely the baby will be sick and have to stay in the hospital longer. A few babies
may even die.
• Smoking during and after pregnancy is a risk factor of sudden infant death syndrome (SIDS). SIDS
is an infant death for which a cause of the death cannot be found.

16
 • Babies born to women who smoke are more likely to have certain birth defects, like a cleft lip or
cleft palate.

RESPIRATORY DISEASES
Any infection of respiratory system may cause it to become inflamed and sore. We cough a lot,
and a large amount of mucus maybe produce which make it difficult to breathe. Any part of the
respiratory system can become infected. Thus, pharyngitis is an inflammation of the pharynx (throat).
Tracheitis is an inflammation of the trachea (windpipe). Bronchitis is an inflammation of the bronchial
tube. Laryngitis is an inflammation of the larynx (voice box), and this may cause us to become hoarse and
lose your voice. Sometimes the pleural membrane surrounding the lungs becomes inflame this is called
pleurisy and can make breathing painful. Sometimes the lungs themselves become inflame for example
chronic inflammation may occur if you breathe in dust over long period of time. The general name for
this condition is pneumoconiosis.

Serve inflammation of lungs may give rise to pneumonia which is cause by a type of bacteria.
Fluid collected in the alveoli, this cuts down the area over which gas exchange can take place, so the
patient gets short of breath.

Another serious disease of the lungs is tuberculosis or TB for short. This is cause by bacteria
which destroy the lung tissue. Today lung cancer as taken over from tuberculosis as a major killer. In lung
cancer a growth develops in the walls of the bronchial tube. This block those, so breathing become more
and more difficult. Unless the growth is discovered and destroyed in time, the cancer may spread to their
neighboring organs such as the liver and spine.

17