What are small vessels that connect arteries to capillaries?

The small vessels that connect arteries to capillaries are known as arterioles. These are smaller branches of arteries that play a crucial role in regulating blood flow and pressure as they lead into the capillaries, which are the sites of exchange of oxygen, nutrients, and waste products with tissues. Arterioles have muscular walls that can constrict or dilate, thus controlling the amount of blood that enters the capillary beds. This regulation is important for maintaining blood pressure and ensuring that tissues receive adequate blood supply.

In contrast, venules are small vessels that carry blood away from the capillaries toward the veins, and capillaries are the very small blood vessels where the actual exchange of substances occurs. The aorta is the main artery that carries oxygen-rich blood from the heart to the rest of the body and does not serve as a connector to capillaries. Each type of vessel has a distinct role within the circulatory system, but arterioles specifically occupy the space between arteries and capillaries, hence their identification as the correct answer in this context.