B4.5 Breathing and gas exchange

Question 1

What is ventilation?

Answer 1

Changing the composition of air in their lungs to maintain a steep concentration gradient for both oxygen diffusing into the blood and carbon dioxide diffusion out of the blood

Question 2

What is alveoli?

Answer 2

Tiny air sacs where diffusion takes place

Question 3

What are bronchioles?

Answer 3

Branches of the trachea

Question 4

What is the bronchi?

Answer 4

The 2 trachea

Question 5

How does the gas exchange takes place in the lung?

Answer 5

As you breath in oxygen moves in - this maintains a steep concentration gradient with the blood. Breathing out removes carbon dioxide - maintains a steep concentration gradient

Question 6

How are the alveoli adapted in terms of surface area?

Answer 6

Lungs are made up of cluster of alveoli which provide a large surface area - as a result achieves the most effective diffusion of oxygen and carbon dioxide.

Question 7

What is another adapted of the alveoli in terms of blood supply?

Answer 7

They have a rich supply of blood capillaries - this maintains a concentration gradient in both directions - blood coming to the lungs is always low in oxygen and high in carbon dioxide compared to the inhaled air - so provides a steep concentration gradient

Question 8

What is an adaption of the membrane in the alveolus?

Answer 8

The layers of the cells between the lungs and capillaries are very thin - this allows diffusion to take place over the shortest possible distance