Starter
1. What is the name of
this cell?
2. What is the main role
of this type of cell?
3. This cell is “adapted” so it can carry
out its role very efficiently.
Describe two such adaptations.
Breathing
 The primary function of breathing is to
supply the blood with oxygen
 Oxygen is needed by every cell in the
body to release the energy from glucose
in a process called respiration.
Asthma
Anatomy of Breathing

Oxygen enters the respiratory system
through the mouth and the nose.

The oxygen then passes through the
larynx (voicebox) and the trachea; which
is a tube that enters the chest cavity.

In the chest cavity, the trachea splits
into two smaller tubes called the bronchi
(singular = bronchus).
Anatomy of Breathing
 Each
bronchus then divides again
forming smaller tubes called
bronchioles.
 The
bronchioles lead
directly into the lungs
where they lead to tiny
sacs called alveoli.
Alveoli
 They
are spherical to
maxmise the surface
area and have very thin
walls
 The
average adult's
lungs contain about
600 million of these
spongy, air-filled sacs
Alveoli
 The
inhaled oxygen passes into the
alveoli through and then diffuses
through the capillaries into the blood.
 Carbon
dioxide from the veins is
released into the alveoli and follows
the same path out of the lungs when
you exhale.
Gas exchange at the alveoli
The alveoli are bunches of
tiny air sacks inside the
lungs.
Each individual sack is
called an alveolus.
When you breathe in, they
fill with air.
The alveoli are covered in tiny capillaries (blood vessels).
Gases can pass through the thin walls of each alveolus and capillary,
and into the blood stream.
Gases can also pass from the blood stream, into the alveolus.
Gas exchange at the alveoli
The Breathing System
The
nasal
passages
and
lungs
Air is drawn into the body via the nose or mouth.
There are advantages to breathing through your nose:
the air is warmed so that it is closer to
body temperature
tiny hairs and mucus in the nose filter the
air, preventing larger dust and pollen
particles reaching the alveoli
mucus moistens the air, making it easier
for the alveoli to absorb.
Air then travels through the larynx, trachea
(windpipe), bronchi (one bronchus to each lung) and
bronchioles to the alveoli, where oxygen passes into
the bloodstream.
Mechanisms of breathing – inspiration
When you breathe in:
intercostal muscles between the
ribs contract, pulling the chest
walls up and out
Intercostal muscles
pull ribs up and out
the diaphragm muscle
below the lungs contracts and
flattens, increasing the size of
the chest
the lungs increase in size, so the
pressure inside them falls. This
causes air to rush in through the
nose or mouth.
Diaphragm
contracts and
moves down
Mechanisms of breathing – expiration
When you breathe out:
Ribs move in
and down
Intercostal muscles between the
ribs relax so that the chest walls
move in and down.
The diaphragm muscle below the
lungs relaxes and bulges up,
reducing the size of the chest.
Diaphragm
relaxes and
bulges up
The lungs decrease in size, so the
pressure inside increases and air is
pushed up the trachea and out
through the nose or mouth.
Mechanisms of breathing – inspiration
Mechanisms of breathing – expiration
Aveoli are spherical (ball-shaped), have
thin and moist walls, and surrounded by
many capillaries. Explain why:
1) Aveoli are spherical
2) Aveoli have thin and moist walls
3) Aveoli are surrounded by many
capillaries
Gas exchange at the alveoli
MRS GREN?
What is “respiration”?
What is respiration?
Respiration is the process that the body uses to release
energy from digested food (glucose):
glucose
from the
digestive
system
oxygen
carbon
dioxide
water
energy
from the
breathing
system
waste
product
exhaled
waste
product
exhaled
useful!
This type of respiration is called aerobic respiration because
energy is released with oxygen.
How do the glucose and oxygen needed for aerobic
respiration get to the all the body’s cells?
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Aerobic and anaerobic respiration
Aerobic respiration
When the body is able to supply the cells with the oxygen and
glucose that they need, it carries out aerobic respiration.
glucose
oxygen
carbon
dioxide
water
energy
Anaerobic respiration
When the body cannot supply the cells with the oxygen
needed to break down glucose, then it has to carry out
anaerobic respiration. Energy is released without oxygen:
glucose
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lactic
acid
energy
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2004
Not enough oxygen!
glucose
lactic
acid
energy
When anaerobic respiration takes place, the lactic acid
produced soaks the muscle cells and prevents muscles from
doing their job. This causes fatigue and sometimes cramp.
After activity that has lead to anaerobic
respiration, the person involved pants
and breathes heavily.
This happens because they need lots of
oxygen to get rid of lactic acid that has
built up in their body.
lactic
acid
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oxygen
carbon
dioxide
water
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What is respiration?
Respiration is the process that the body
uses to release energy from digested food
(glucose) by reacting it with oxygen.
glucose
from the
digestive
system
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oxygen
carbon
dioxide
water
energy
from the
breathing
system
waste
product
exhaled
waste
product
exhaled
useful!
© Boardworks Ltd 2005
2004
1) What is respiration? Describe in
words.
2) Write down the respiration
equation.
3) Why do we breathe?
4) How is breathing different from
respiration?
5) What is gas exchange?
Gas exchange at the alveoli
Inhaled air vs. Exhaled air
Gas
Oxygen
Amount in
inhaled air
Amount in
exhaled air
21%
17%
Carbon dioxide Very small amount
Nitrogen
Water vapour
3%
79%
79%
Small amount
Large amount
1) Find the differences
2) Explain the differences
Questions
1. Why are there less oxygen and more carbon
dioxide in the exhaled air?
2. Why is the amount of nitrogen unchanged?
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Comparing inhaled and exhaled air
What are the differences between inhaled and exhaled air?
inhaled air
nitrogen (78%)
oxygen (21%)
carbon dioxide (0.04%)
other
exhaled air
nitrogen (78%)
oxygen (17%)
carbon dioxide (4%)
other
How could you test for the differences between inhaled and
exhaled air?
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Practical – Air goes in, Air goes out
Practical – How much air can you
breathe in?
Questions:
1. What is the benefit of the lungs having tiny
air sacs rather than just one large structure?
2. What process enables oxygen and carbon
dioxide to move across the alveolus wall?
3. How is the alveolus wall adapted for
efficient movement of gas molecules?
4. What is the name of the red pigment in
blood that bonds with oxygen?
The respiratory system and health
Why is a respiratory system that works
properly essential for good health?
The respiratory system provides the
body with the oxygen it needs for
respiration.
The lungs are delicate, spongy
organs that deal with 12,000 litres of
air each day.
Smoking is a very dangerous habit that has serious effects on the
lungs and respiratory system.
How does smoking damage health and fitness?
1) What is respiration? Describe in
words.
2) Write down the respiration
equation.
3) Why do we breathe?
4) How is breathing different from
respiration?
5) What is gas exchange?
1) Write down the respiration
equation (in words)
2) What are the three differences
between inhaled air and exhaled
air?
3) What would happen to the body if
alveoli inside the lungs are filled
with liquid?
Asthma
Bronchitis
Emphysema
 Caused
by exposure to toxic
chemicals or long-term exposure to
tobacco smoke.
Emphysema
How does smoking affect the lungs?
Which picture shows the healthy lungs of a non-smoker and which
show the unhealthy lungs of a smoker?
healthy lungs
smoker’s lungs
Not a difficult question to answer but some people still think
that smoking is cool!
How does smoking affect health?
dental hygiene
problems
facial wrinkles
asthma
lung cancer
impaired
immune system
emphysema
mouth, lip and
throat cancer
pancreatic cancer
testicular cancer
liver cancer
heart disease
cervical cancer
kidney cancer
Effects of smoking on
health
bronchitis
osteoporosis
menstrual
problems
leukaemia
sperm abnormalities
and impotence
stomach cancer
bladder cancer
Smoker’s cough
Task
Make an anti-smoking poster
for teenagers