breathing and gas exchange

Question 1

what happens when you breathe in?

Answer 1

the internal intercostal muscles relax and the external intercostal muscles contract, pulling the ribcage upwards and outwards. the diaphragm contracts, pulling downwards. lung volume increases, air pressure inside decreases. air is pushed into the lungs

Question 2

what happens when you breathe out?

Answer 2

the external intercostal muscles relax and the internal intercostal muscles contract, pulling the ribcage downwards and inwards. the diaphragm relaxes, moving back upwards. lung volume decreases, air pressure inside increases. air is pushed out of the lungs