What is the primary function of capillaries?

What is the primary function of capillaries?

• A. They Pump Blood To The Heart.
• B. They Transport Oxygen.
• C. They Serve As Exchange Vessels For Nutrients, Wastes, Fluids.
• D. They Store Blood.

Answer: (C)

Capillaries are the site where exchange between blood and tissues happens. Their walls are extremely thin—often just one cell thick—and they form vast networks, giving them a huge surface area. This setup allows nutrients and oxygen in the blood to diffuse out into surrounding tissues, while wastes and carbon dioxide diffuse from the tissues back into the blood. Fluids also move across the capillary walls to help maintain tissue fluid balance. So, the primary role of capillaries is to serve as exchange vessels for nutrients, wastes, and fluids. Rationale for why the other ideas aren’t the main function: capillaries don’t pump blood themselves—that’s the job of the heart and larger vessels. They don’t store blood; storage is mainly in veins and certain organs. Oxygen transport is a broader role of the circulatory system, with red blood cells carrying oxygen, and capillaries facilitating its transfer to tissues rather than serving as the system’s primary function.

Capillaries are the site where exchange between blood and tissues happens. Their walls are extremely thin—often just one cell thick—and they form vast networks, giving them a huge surface area. This setup allows nutrients and oxygen in the blood to diffuse out into surrounding tissues, while wastes and carbon dioxide diffuse from the tissues back into the blood. Fluids also move across the capillary walls to help maintain tissue fluid balance. So, the primary role of capillaries is to serve as exchange vessels for nutrients, wastes, and fluids.

Rationale for why the other ideas aren’t the main function: capillaries don’t pump blood themselves—that’s the job of the heart and larger vessels. They don’t store blood; storage is mainly in veins and certain organs. Oxygen transport is a broader role of the circulatory system, with red blood cells carrying oxygen, and capillaries facilitating its transfer to tissues rather than serving as the system’s primary function.