memorisor

Question 1

breathing in

Answer 1

inhalation / inspiration
- external intercostal muscles contract, internal intercostal muscles relax
- ribs swing upwards and outwards
- sternum moves up and further away from backbone
- diaphragm contracts and flattens (thoracic cavity increases)
- air pressure in the lungs causes the lungs to expand to fill up the enlarged space
- expansion of lungs results in reduced air pressure in the lungs
- air pressure in the lungs is now lower than atmospheric pressure
- air is forced into the lungs until the air pressure in the lungs and that in atmosphere are equal

Question 2

breathing out

Answer 2

exhalation / expiration
- external intercostal muscles relax, internal intercostal muscles contract
- ribs move downwards and inwards
- sternum moves down to its original position
- diaphragm relaxes and arches upwards (volume of thoracic cavity decreases)
- lungs are compressed and air inside them increases as the volume decreases
- air pressure in the lungs is now higher than atmospheric pressure
- air is forced out of lungs until the air pressure in the lungs and that in atmosphere are equal

Question 3

blood clot