Capillary

Definition

A capillary is a small blood vessel where gas, nutrient, and waste exchange occurs between blood and tissues. It connects arterioles and venules.

5 Must Know Facts For Your Next Test

1. Capillaries have thin walls consisting of a single layer of endothelial cells to facilitate efficient exchange.
2. They are the smallest blood vessels in the circulatory system, typically about 5-10 micrometers in diameter.
3. Capillaries form extensive networks called capillary beds that increase surface area for exchange.
4. Blood flow through capillaries is regulated by precapillary sphincters which control their opening and closing.
5. Capillaries play a crucial role in maintaining homeostasis by regulating the movement of substances between blood and interstitial fluid.

Review Questions

Related terms

Arteriole: A small branch of an artery leading into capillaries.

Venule: A small vein that collects blood from capillaries to return it to larger veins.

Endothelial Cells: Cells lining the interior surface of blood vessels including capillaries.