B3.1 Gas Exchange

Question 1

inspiration process

Answer 1

external intercostal muscles contract
ribcage moves up and out
diaphragm contracts and flattens
vol of thorax increases
pressure inside decreases
air is drawn in

Question 2

expiration process

Answer 2

external intercostal muscles relax
ribcage moves down and in
diaphragm relaxes and becomes dome shaped
vol of thorax decreases
pressure inside thorax increases
air is forced out