Exchange surfaces and breathing

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Page 58 Fact recall

1a) Oxygen and nutrients

b) Carbon dioxide and urea

2) Large diffusion distance, small SA:V

Page 61 Application

1) It will receive less oxygenated blood supply, decreasing the concentration gradient for diffusion of gases = slower diffusion rate

2) Less oxygen reaching alveoli = decreases concentration gradient = slow rate of diffusion between alveoli and capillaries

3a) Alveoli are larger in the diseased lung tissue

b) Loss of elasticity in alveoli, larger alveoli gives small surface area for gas exchange, so rate of diffusion of oxygen would be slower

Page 62 Fact recall

1) Oxygen goes into alveoli air space, diffused out of alveoli, across alveolar epithelium and capillary endothelium and into capillaries, taken up by haemoglobin in the blood

2) Contain many alveoli - large surface area, thin diffusion distance, good blood supply = increasing rate of diffusion

3a) To secrete mucus to trap microorganisms and dust particles, preventing them from reaching alveoli

b) To waft mucus up airways to be swallowed

4) Function - Stretch and recoil to prevent alveoli bursting, stretch and recoil in airways to help push air out of lungs

5) Trachea and bronchi

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