What is the primary function of blood capillaries?

The primary function of blood capillaries is to connect arteries and veins, facilitating the exchange of substances between the blood and surrounding tissues. Capillaries are the smallest blood vessels in the body and play a crucial role in the circulatory system. They enable the transfer of oxygen, nutrients, carbon dioxide, and waste products to and from cells, serving as a bridge between the arterial and venous systems.

Blood flows from arteries into capillaries, where the exchange occurs, and then returns to the heart through veins. Their extensive network ensures that all tissues receive adequate blood supply, which is vital for cellular metabolism and overall homeostasis.

This understanding clarifies why storing excess blood, regulating blood pressure, or transporting blood from the heart does not capture the primary role of capillaries in the circulatory system.