A tiny vein that drains blood from capillaries is called a

• A. Vein
• B. Venule
• C. Capillary
• D. Arteriole

Answer: (B)

This question tests understanding of the vessels that drain capillary beds and return blood toward the heart. After blood passes through capillaries, it is collected by small vessels called venules, which then feed into larger veins.

A venule is the tiny vessel that drains blood from capillaries. It stands between capillaries and veins, collecting the low-oxygenated blood from the exchange sites and guiding it into the venous system that returns blood to the heart.

In contrast, a vein is a larger vessel that carries blood back toward the heart, not specifically the tiny drain from capillaries. A capillary is the microscopic vessel where exchange occurs, not a drainage vessel. An arteriole is a small artery that delivers blood to capillaries, not drain from them.