7.2

Question 1

What do the external intercostal muscles do?

Answer 1

Move the rib cage upwards and outwards.

Question 2

What happens when you breath in?
(Include which muscles contract/relax and points about pressure)

Answer 2

The external intercostal muscles contract
The internal intercostal muscles relax
The diaphragm contracts
The thoracic cavity increases

The lung pressure decreases so a pressure gradient is created between outside and inside of the lungs.
So the air flows down the gradient into the lungs, down the trachea and into the alveoli.

Question 3

What happens when you breath out?
(Include which muscles contract/relax and points about pressure)

Answer 3

The external intercostal muscles and the diaphragm relax.
The internal intercostal muscles contract.
The rib cage moves downwards and inwards and the diaphragm moves upwards.
The volume of the thoracic cavity decreases.
Lung pressure in the lungs increases.
Air flows out of the lungs, down the concentration gradient.