Which blood vessel type is responsible for nutrient and gas exchange in tissues?

Capillaries are the blood vessel type specifically designed for nutrient and gas exchange in tissues. These tiny vessels have thin walls that allow for the efficient transfer of oxygen, carbon dioxide, nutrients, and waste products between the blood and surrounding tissues. The structure of capillaries, which consists of a single layer of endothelial cells, facilitates this exchange process, making them ideally suited for their role in the circulatory system.

The other types of blood vessels play different roles. Arteries carry oxygen-rich blood away from the heart to various parts of the body, but they do not directly facilitate the exchange of materials with tissues. Veins return deoxygenated blood back to the heart, again not being directly involved in the exchange process at the tissue level. Arterioles, while they are small branches of arteries leading to capillaries, serve mainly to regulate blood flow and pressure, rather than being the primary sites for exchange. Thus, capillaries are uniquely positioned to perform the critical function of nutrient and gas exchange in the body.