RESPIRATION AND GAS EXCHANGE
Respiration
Aerobic and anaerobic respiration
http://www.bbc.co.uk/schools/gcsebitesize/pe/appliedanat
omy/1_anatomy_respiratorysys_rev2.shtml
Define respiration as the chemical reactions that break
down nutrient molecules in living cells to release
energy.
• Remember respiration is a chemical process
• Which releases energy from food
• Don’t confuse it with the exchange of gases or
breathing
State the uses of energy in the body of humans:
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muscle contraction,
protein synthesis,
cell division,
growth,
the passage of nerve impulses
the maintenance of a constant body temperature
• ALL these processes require energy
• You need to be able to quote these
Aerobic respiration
Define aerobic respiration as the release of a relatively large
amount of energy in cells by the breakdown of food
substances in the presence of oxygen.
• Remember aerobic respiration needs oxygen
• It releases a lot of energy
State the word equation for aerobic
respiration.
• Food + oxygen
carbon dioxide + water
State the equation for aerobic respiration using
symbols
• C6H12O6 + 6O2 → 6CO2 + 6H2O
• Learn this equation
• You’ll need it if you’re doing the higher tier
Anaerobic respiration
Define anaerobic respiration
• the release of a relatively small amount of
energy by the breakdown of food substances
• in the absence of oxygen.
• Because the food is not completely broken
down some of the energy remains in the
waste products
State the word equation for anaerobic
respiration
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in muscles during hard exercise
glucose → lactic acid
and the microorganism yeast
glucose → alcohol + carbon dioxide
Note that a lot of the energy here remains
locked up in the lactic acid or alcohol
Compare aerobic respiration and anaerobic respiration in terms
of relative amounts of energy released.
• Aerobic respiration produces much more energy ATP
than anaerobic respiration
• Look at the diagram below and compare the number
of ATP molecules
State the balanced equation for anaerobic
respiration in
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muscles
C6H12O6 → 2C3H6O3
and the microorganism yeast
C6H12O6 → 2C2H5OH + 2CO2
using symbols
You should learn these
Note that no carbon dioxide is produced in
anaerobic respiration in animals
Describe the role of anaerobic respiration in
yeast during brewing and bread-making.
• http://blowers.chee.arizona.edu/cooking/kine
tics/bread.html
Bread making
The fermentation process serves three primary
purposes:
• To produce carbon dioxide gas to create a light
and airy texture in the bread
• To enhance the flavour of the bread
• To change the protein structure of the bread
to prevent a chewy texture
Beer making
• Similar to baking bread, yeast is critical to
making beer.
• Yeast is added to the wort to turn the sugars
into alcohol and carbon dioxide
• This process is called fermentation.
Describe the effect of lactic acid in muscles during
exercise (include oxygen debt in outline only).
• Lactic acid build up is often blamed for post
workout muscle fatigue and pain
• During short intense burst of exercise such as
sprinting
• Energy is generated anaerobically or without
oxygen.
• Lactic acid builds up
• When you stop exercising you are still breathing
heavily.
• This is your body taking in extra oxygen to
'repay' the oxygen debt.
• When you stop sprinting and start to recover
you will actually need more oxygen to recover
• This is oxygen is used to break down the lactic
acid
• The difference between the oxygen the body
required and what it actually managed to take
in during the sudden sprint is called oxygen
deficit.
Gas exchange
List the features of gas exchange surfaces in
animals.
• Large surface area
 So diffusion is more efficient
• Moist
 So gases can dissolve
• Good blood supply
 To remove the oxygen and maintain
concentration gradient
• Ventilation system
 To bring more supplies of oxygen
Cross-section through leaf
Circulation of gases
in and out of leaf
Identify on diagrams and name the larynx, trachea,
bronchi, bronchioles, alveoli and associated capillaries
• This is a useful
website
•
http://www.bbc.co.uk/schools
/gcsebitesize/pe/appliedanato
my/1_anatomy_respiratorysys
_rev1.shtml
The Breathing System
• Function is to take air into and out of
the lungs to allow gas exchange
• Oxygen moves from the lung to the
blood
• Carbon dioxide moves from the blood
into the lung
• Gases move by diffusion
The Breathing System
Rib
Sternum
Intercostal
muscle
Cartilage
Right lung
Backbone
Passage of Air
Nose
Throat
Trachea
Bronchi
Bronchioles
Alveoli (air sacs)
GAS EXCHANGE
The alveoli
Explain the role of mucus and cilia in protecting the
gas exchange system from pathogens and particles.
• Mucus traps the pathogens and particles
• Cilia move the mucus upwards to the mouth
where it is swallowed
The structure of the trachea
C-shaped ring
of cartilage
Ciliated cells
The structure of the trachea
Ciliated cells and mucussecreting cells
•Located in trachea, bronchi and
bronchioles
•Mucus is produced by goblet cells
located in the lining of the air tubes
•The mucus traps dirt and
microorganisms
Ciliated cells and mucussecreting cells
•Cilia are tiny hair-like structures on
the top layer of cells
•Cilia waft dust and mucus out of the
lungs
•This process protects against
infection
Describe the role of the ribs, the internal and external
intercostal muscles and the diaphragm in producing volume
and pressure changes leading to the ventilation of the lungs
• You need to learn the sequence of events here
When we breathe in…
Intercostal muscles contract
So, ribcage moves out and up
Diaphragm contracts and flattens
The volume (or space) inside the
thorax increases
• The lungs are stretched to fill that
space
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• The pressure inside the lungs decreases
• Now the pressure outside the body is
higher than the pressure in the lungs
• So, air rushes into the lungs
• THE LUNGS INFLATE - This is inhalation
When we breathe out…
Intercostal muscles relax
So, ribcage moves in and down
Diaphragm relaxes and curves up
The volume (or space) inside the
thorax decreases
• The lungs are return to their original
size
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• The pressure inside the lungs increases
• Now the pressure inside the lungs higher
than the pressure outside the body
• So, air rushes out of the lungs
• This is exhalation
Breathing and gas exchange
• http://people.eku.edu/ritchisong/301notes6.
htm
• There are some good videos here
What is lung capacity?
• Lung capacity is the maximum volume of
air that can be breathed out after a
maximum breath in
• What is your lung capacity?
• Adult male = 4 litres
• Adult female = 3 litres
State the differences in composition
between inspired and expired air.
• Not all the oxygen is removed from the air
• Exhaled air still contains some oxygen but has
much more carbon dioxide and water vapour
than inhaled air
• http://www.bbc.co.uk/schools/gcsebitesize/pe/appliedanatomy/1_anato
my_respiratorysys_rev3.shtml
Is exhaled air different?
Component Inhaled air
Oxygen
Carbon
dioxide
Nitrogen
Water
vapour
Exhaled air
21%
17%
0.04%
4%
78%
78%
Variable
Saturated
Use lime water as a test for carbon dioxide to
investigate the differences in composition between
inspired and expired air.
• Lime water goes cloudy when carbon dioxide
is bubbled through it
• The experiment below uses a different
indicator but lime water could be used with
the same apparatus
• http://seniorscience.wikispaces.com/file/view
/Testing+Exhaled+Air+for+Carbon+dioxide.pdf
• Bromothymol blue can be replaced by
limewater
• Here are the results using
limewater
• Breathe in and out
through the long tube
• One tube has inhaled air
bubbled through it
• The other has exhaled air
bubbled through it
• http://www.sciencephoto.co
m/media/75297/enlarge
Investigate and describe the effects of physical
activity on rate and depth of breathing
• You can try this on yourself or family members
• TAKE CARE if anyone has heart or lung
problems !!!
EFFECT OF EXERCISE ON HEART RATE AND BREATHING
• Measure your heart (pulse) rate breathing rate at rest.
• Do one lot of exercise (10 press ups OR run or walk up one
flight of stairs)
• Take the pulse and breathing rate again
• Wait till you have fully recovered and your pulse has gone
back to normal
• Then do 2 lots of exercise (20 press ups OR run/walk up
two flights of stairs)
• Repeat with three and four lots of exercise.
RESULTS
• Plot a graph of heart rate against amount
of exercise
• Plot another graph of breathing rate
against exercise
• Plot a scatter graph of heart rate against
pulse rate
• You could try this with other members of
your family or friends
Conclusions
• What are trends in your results?
• In a couple of sentences explain the
relationship between exercise, heart rate and
breathing rate.
• What is the biological explanation for your
results?
Evaluation
• Look at your method and explain whether or
not this was an accurate measure of the
effects of exercise on the heart and lungs.
• Suggest some improvements to this
experiment
• Write up and send me your experiment
Explain the link between physical activity and rate and
depth of breathing
• in terms of
• changes in the rate at which tissues respire
• and therefore of carbon dioxide
concentration
• and pH in tissues
• and in the blood
Effects of exercise
The body needs much more Oxygen. The
breathing becomes faster and deeper and
produces a large vol. of Oxygen. More
Carbon Dioxide is produced which is the
waste product, which blood carries back to
the lungs to be exhaled
Because the body needs more
blood to carry more Oxygen and
waste products the blood is diverted
from parts of the body that don’t
require it for example the blood in
the stomach is reduced.
More H2O and heat are produced
and eliminated by sweating and
exhaling. The blood must carry these
waste products away from the
muscle cells, this is why the breath is
hot and moist during exercise.
Muscles are required to contract and
relax in specific areas of the body.
People taking part in exercise go
red because the Veins carrying
warm blood back to the heart
divert the blood nearer the skins
surface. This is called Vasodilation.
The heat is then lost through
radiation through the skin.
The heart beats faster and pumps
blood around the body faster.
The heart also fills up with more
blood and squeezes more blood
out with each contraction. The
Heart Rate, Stroke Vol., Cardiac
Output, and Blood Pressure all
increase during exercise.
Effects on pH
• The pH of the blood is maintained at about pH 7
• When carbon dioxide (CO2) gas dissolves in
water, it forms carbonic acid
• This lowers the blood pH
• The pH of the tissue fluid also lowers
• This is detected by the brain which increases
the heart and breathing rate
What happens when we exercise?
• Exercise increases the rate of which
process?
 RESPIRATION
• Why?
More energy needed for muscle
contraction
• How?
ATP is formed when food is broken
down.
This releases more carbon dioxide
How does the breathing system
respond to exercise?
• Exercise causes the rate and depth of
breathing to increase
• The heart rate increases
• The stroke volume of the heart
increases
• This increases the supply of
oxygen and glucose to the muscles
• And increases the rate of removal
of carbon dioxide, lactic acid and
heat from the muscles
EFFECT OF EXERCISE ON HEART RATE AND BREATHING
• Measure your heart (pulse) rate breathing rate at rest.
• Do one lot of exercise (10 press ups OR run or walk up one
flight of stairs)
• Take the pulse and breathing rate again
• Wait till you have fully recovered and your pulse has gone
back to normal
• Then do 2 lots of exercise (20 press ups OR run/walk up
two flights of stairs)
• Repeat with three and four lots of exercise.
Describe the effects of tobacco smoke and its major
toxic components on the gas exchange system.
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tar,
nicotine,
carbon monoxide,
smoke particles
http://www.bbc.co.uk/schools/ks3bitesize/sci
ence/organisms_behaviour_health/diet_drugs
/revise7.shtml
Smoking
Tar
• Tar causes cancer of the lungs, mouth and
throat.
• It coats the surface of the breathing tubes and
the alveoli.
• This causes coughing and damages the alveoli,
making it more difficult for gas exchange to
happen.
Smoke
• Cells in the lining of the breathing tubes produce
sticky mucus to trap dirt and microbes.
• Cells with tiny hair-like parts, called cilia,
normally move the mucus out of the lungs.
• Hot smoke and tar from smoking damages the
cilia.
• So smokers cough to move the mucus and are
more likely to get bronchitis.
Nicotine
• Nicotine is addictive - it causes a smoker to
want more cigarettes.
• Nicotine also increases the heart rate and
blood pressure, and makes blood vessels
narrower than normal.
• This can lead to heart disease.
Carbon monoxide
• Carbon monoxide is a gas that takes the place
of oxygen in red blood cells.
• This reduces the amount of oxygen that the
blood can carry.
• This means that the circulatory system has to
work harder, causing heart disease.