In the Alveoli and Lung Capillaries, How are Carbon Dioxide

Question

In the alveoli and lung capillaries, how are carbon dioxide and oxygen exchanged?
A) by endocytosis
B) by osmosis
C) by diffusion
D) by phagocytosis

Accepted Answer

Carbon dioxide and oxygen are exchanged through diffusion. Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. In the alveoli, oxygen moves from the air sacs into the surrounding capillaries, where it binds to hemoglobin in red blood cells. At the same time, carbon dioxide moves from the capillaries into the alveoli and is then exhaled out of the body.