human gas exchange

Question 1

Describe the structure of alveoli.

Answer 1

Alveoli are tiny air sacs with a one-cell-thick layer of epithelial cells

Question 2

Describe the structure of capillaries.

Answer 2

Capillaries are blood vessels with a one-cell-thick layer of endothelial cells.

Question 3

what happens during gas exchange within the alveoi

Answer 3

During gas exchange in the lungs, oxygen and carbon dioxide move between the alveolus and the capillary by diffusing down condenstrationgradients.

Question 4

How are alveoli adapted for efficient gas exchange?

Answer 4

1. The alveolar epithelium is one cell thick, which creates a short diffusion distance for gas exchange. Note: in the exam, it is not enough to say the epithelium is ‘thin’.
2. The lungs contain a large number of alveoli. This provides a large surface area for gas exchange.
3. There is a steep concentration gradient for oxygen and carbon dioxide.

Question 5

How is a steep concentration gradient of oxygen and carbon dioxide maintained between the alveoli and capillaries?

Answer 5

Ventilation is the process of moving air in and out of the lungs. This ensures a lot of oxygen enters the lungs and a lot of carbon dioxide exits the lungs.

A good blood supply ensures that blood containing a lot of oxygen is quickly taken away from the lungs and blood containing a lot of carbon dioxide is taken towards the lungs.