Which term refers to small blood vessels that facilitate gas and nutrient exchange?

Capillaries are the smallest blood vessels in the circulatory system and play a crucial role in facilitating gas and nutrient exchange between the blood and surrounding tissues. Their thin walls, composed of a single layer of endothelial cells, allow for efficient diffusion of oxygen, carbon dioxide, nutrients, and waste products. This unique structure is essential for maintaining homeostasis within the body, as it enables the delivery of necessary substances to cells and the removal of metabolic waste.

In contrast, veins and arteries serve different functions within the circulatory system. Veins carry deoxygenated blood back to the heart, while arteries transport oxygen-rich blood away from the heart to the tissues. Arterioles, being smaller branches of arteries, regulate blood flow into the capillaries but do not directly participate in the exchange process that capillaries are specifically designed for. Therefore, the correct term for the vessels that facilitate gas and nutrient exchange is indeed capillaries.