B3.1 Gas exchange

Question 1

What is ventilation

Answer 1

the exchange of air between the atmosphere & lungs

Question 2

What is gas exchange

Answer 2

the exchange of oxygen & carbon dioxide between the alveoli & bloodstream (via passive diffusion) across a membrane

Question 3

What is cell respiration

Answer 3

the release of energy (ATP) from organic molecules, enhanced by presence of oxygen

Question 4

How does gas exchange work

Answer 4

1. Oxygen from lungs taken into the alveoli diffuses into the blood of the surrounding capillaries
2. High concentration of carbon dioxide in the blood of the capillaries diffuse into the alveoli to be expelled by the lungs

Question 5

What are the features of gas exchange surfaces

Answer 5

1. Large SA - faster diffusion
2. Thin walls - short diffusion distance
3. Good ventilation with air - maintain diffusion gradient
4. Good blood supply - maintain high concentration gradient = faster diffusion

Question 6

How to maximise rate of diffusion

Answer 6

1. Permeable membrane
2. Surface must be moist
3. Surface must have large SA to volume ratio
4. Surface must be thin
5. Large concentration gradient across the respiratory surface