What are arterioles?

Arterioles are best defined as small blood vessels that play a crucial role in the circulatory system by connecting arteries to capillaries. This connection is essential for the transition from higher-pressure arterial flow to the lower-pressure capillary system. Arterioles are primarily responsible for regulating blood flow and pressure through a process known as vasodilation and vasoconstriction, which actively adjusts the diameter of the vessels in response to the body's needs.

By constricting or relaxing, arterioles control the amount of blood that enters capillary beds, where the exchange of gases, nutrients, and waste occurs between the blood and surrounding tissues. The correct answer emphasizes this vital role of arterioles in the circulatory system.