gas exchange

Question 1

describe how the human gas exchange system works (6 marks)

Answer 1

1. trachea - bronchi - brochioles - alveoli
2. breathing in: external intercostal muscles contracts, diaphragm contracts
3. volume increases, pressure decreases in lungs –> air moves in
4. breathing out: internal intercostal muscles contracts, diaphragm relaxes
5. volume of air decreases, pressure increases in lungs –> air moves out