RESPIRATION AND GAS EXCHANGE

Respiration

Aerobic and anaerobic respiration

http://www.bbc.co.uk/schools/gcsebitesize/pe/appliedanatomy/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:

• 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

• 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

• 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/kinetics/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 supplyTo remove the oxygen and maintain concentration

gradient• Ventilation system To bring more supplies of oxygen

Circulation of gases in and out of leaf

Cross-section through 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/appliedanatomy/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

Right lung

Backbone

Cartilage

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 mucus-secreting 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 mucus-secreting 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

• 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

• 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_anatomy_respiratorysys_rev3.shtml

Is exhaled air different?

Component

Inhaled air

Exhaled air

Oxygen 21% 17%

Carbondioxide

0.04% 4%

Nitrogen 78% 78%

Watervapour

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.com/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 exerciseThe 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.

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.

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.

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.

• tar, • nicotine, • carbon monoxide, • smoke particles• http://

www.bbc.co.uk/schools/ks3bitesize/science/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.