Breathing in and breathing out

Question 1

What does ventilation (breathing) ensure?

Answer 1

That air with a high concentration of oxygen is taken into the lungs, and air with a high concentration of carbon dioxide is removed from the lungs

Question 2

What does ventilation maintain and what does this increase?

Answer 2

High concentration gradients between air (inside your alveoli) and blood, increasing the rate of diffusion of oxygen and carbon dioxide

Question 3

If volume of an enclosed space is increased, what does air pressure do inside it?

Answer 3

Decreases

Question 4

Where are the lungs suspended?

Answer 4

In the airtight thorax

Question 5

What does increasing the volume of the thorax do?

Answer 5

Decreases the air pressure in the lungs to below atmospheric pressure

Question 6

What happens when air flows into the lungs?

Answer 6

It inflates them until the pressure in the alveoli equals that of the atmosphere

Question 7

What does decreasing the volume of the thorax do?

Answer 7

Increases the pressure in the lungs and air flows out until the pressure in the alveoli drops to atmospheric pressure

Question 8

List three things that happen when breathing in

Answer 8

1. Intercostal muscles and diaphragm ( a muscular sheet) contract
2. Thorax volume increases
3. This decreases the pressure, so air flows in

Question 9

List three things that happen when breathing out

Answer 9

1. Intercostal muscles and diaphragm relax
2. Thorax volume decreases
3. This increases the pressure, so air flows out