respiratory system

Question 1

How does inspiration occur?

Answer 1

1. intercostal muscles contract moving ribs up and out
2. diaphragm contracts and flattens
3. chest cavity increases in volume and decreases in pressure. The pressure is below what it is outside of the body so air is sucked in to equalise the pressure

Question 2

How does expiration occur?

Answer 2

1. interocstal muscles relax and ribs move down and in
2. diaphragm relaxes and domes up
3. chest cavity decreases in volume and increases in pressure. Pressure outside the body is higher so air is forced out of the lungs to equalise

Question 3

How are alveoli adapted for efficient gas exchange?

Answer 3

• good blood supply
• large surface area
• thin walls
• moist lining