B3.1.2 Gaseous exchange

Question 1

Where are the lungs located in the body?

Answer 1

In the upper part of the body (thorax)

Protected by the ribcage

Separated from the lower part of the body (abdomen) by the diaphragm.

Question 2

What two functions is the breathing system adapted for?

Answer 2

ventilation – the movement of air into and out of the lungs

gas exchange – the ‘swapping’ of gases between the alveoli and the blood

Question 3

What happens when you inhale?

Answer 3

The intercostal muscles contract, expanding the ribcage outwards and upwards.

The diaphragm contracts, pulling downwards to increase the volume of the chest.

Pressure inside the chest is lowered and air is sucked into the lungs.

Question 4

What happens when you exhale?

Answer 4

The intercostal muscles relax, the ribcage drops inwards and downwards.

The diaphragm relaxes, moving back upwards, decreasing the volume of the chest.

Pressure inside the chest increases and air is forced out.

Question 5

What happens in the alveoli?

Answer 5

Oxygen diffuses into the blood

Carbon dioxide diffuses out of the blood.