M3 C7 Exchange surfaces

Question 1

describe the mechanism of inspiration [5]

Answer 1

• diaphragm constricts & flattens
• external intercostal muscles constrict, ribs move up & out
• increases volume of thorax
• decreases the pressure in the thorax
• air moves in from high to low pressure

Question 2

describe the mechanism of expiration

Answer 2

• diapgragm