Pack 7 - Gas Exchnage

Question 1

Describe and explain the advantage of the counter current principle in gas exchange cross a fish gill

Answer 1

• oxygen and blood flow in opposite directions

- this is so the concentration gradient across of oxygen is maintained across the whole length of the lamellae

Question 2

Describe and explain the mechanism that causes lungs to fill with air

Answer 2

Diaphragm contract and flatten
Increases thoracic volume
Decreases air pressure
Air forced into lungs down pressure gradient