Which blood vessels have valves?

Veins are blood vessels that carry blood from different body parts back to the heart. They are part of the circulatory system and work in conjunction with arteries, which carry oxygenated blood away from the heart to the body's tissues. Veins have thinner walls than arteries and contain valves that help prevent the backward flow of blood. Blood in veins is typically low in oxygen and high in carbon dioxide, waste products, and deoxygenated blood.