What are desirable characteristics for a gas exchange surface, such as the endothelial cells lining the inside of lung? (Select all that apply.)

a. a thickness under 10 micrometers

b. a small surface area

c. a large surface area

d. a thickness of 100 micrometers

a. a thickness under 10 micrometers

c. a large surface area

Explanation:

Endothelial cells line the surface of blood capillaries and therefore is a component of the respiratory membrane through which the gaseous exchange occurs. The endothelium is a very thin cell layer and makes the respiratory membrane a 0.2 to 0.6 micrometers thick layer. The thin respiratory membrane facilitates gaseous exchange between alveolar air and blood present in the capillaries.

The total surface area of the respiratory membrane also affects the gaseous exchange. The large surface area results in an increased rate of gaseous exchange since the process occurs by diffusion. The rate of diffuse is increased with the increased surface area. Alveoli, the balloon-shaped structures that make the lungs serve to increase the surface area for the respiratory membrane.