Which blood vessel type typically has valves to prevent backflow?

Veins typically have valves to prevent backflow. This structural feature is essential because veins carry blood back to the heart at a lower pressure compared to arteries. The presence of valves in veins helps ensure that blood flows in one direction toward the heart, particularly in the limbs, where blood must travel against gravity. These valves close if blood begins to flow backward, which is critical in maintaining efficient circulation and preventing conditions such as venous insufficiency.

In contrast, arteries, which transport blood away from the heart under high pressure, do not have valves because the pressure from the heart's pumping action keeps the blood moving forward. Capillaries, being very small vessels where nutrient and gas exchange occurs, do not have valves either as they function at a level where backflow is not a concern. Arterioles, the smaller branches of arteries, similarly lack valves as they also contribute to forward blood flow under pressure.