ventilation

Question 1

what is ventilation?

Answer 1

• process of pulling air into the lungs/thorax
• occurs due to pressure
• helps to maintain concentration gradient

Question 2

process of inspiration

Answer 2

• external intercostal muscles contract, internal intercostal muscles relax
• rib cage moves upwards and out, pulls on pleural membranes and on alveoli, opening them
• diaphragm contracts and flattens
• increases volume in lungs, decreases pressure in lungs
• higher air pressure in atmosphere than in the lungs, air moves in

Question 3

describe the process of expiration

Answer 3

• internal intercostal muscles contract, external intercostal muscles
• rib cage moves downwards out in
• diaphragm relaxes, moves into dome shape
• decreases volume of lungs/thorax, increases air pressure in lungs
• air pressure in lungs higher than in the atmosphere, air moves out