Answer the following question given this paragraph: 

Veins are blood vessels that carry blood toward the heart. This blood is no longer under much pressure, so many veins have valves that prevent backflow of blood. Veins generally carry deoxygenated blood. The largest vein is the inferior vena cava, which carries blood from the lower body to the heart.


Q: Veins are blood vessels that carry blood toward what?


A:
heart