At the arterial end of the tissue capillaries,
A) O2 diffuses from tissue cells into the blood, while CO2 diffuses from the blood into tissue cells.
B) O2 diffuses from the blood into tissue cells, while CO2 diffuses from tissue cells into the blood.
C) both O2 and CO2 diffuse from the blood into tissue cells.
D) both O2 and CO2 diffuse from tissue cells into the blood.
E) O2 diffuses from the blood into tissue cells, but there is no net movement of CO2.

Question

Quizplus · Accepted Answer

At the arterial end of tissue capillaries, there is a higher concentration of oxygen in the blood than in the tissue cells. As a result, oxygen diffuses from the blood into tissue cells. On the other hand, there is a higher concentration of carbon dioxide in the tissue cells than in the blood. Therefore, carbon dioxide diffuses from tissue cells into the blood. This process is facilitated by the concentration gradient between blood and tissue cells.

At the Arterial End of the Tissue Capillaries