The velocity of blood flow slows in the capillaries in association with an increase in total cross-sectional area.

Question

Quizplus · Accepted Answer

This is known as the "capillary paradox". While the total cross-sectional area of the capillaries is large, the individual capillaries are very narrow, which causes the velocity of blood flow to slow down. This slowing of velocity allows for more time for exchange of substances (such as oxygen, carbon dioxide, and nutrients) between the blood and the surrounding tissues.

The Velocity of Blood Flow Slows in the Capillaries in Association