What are the differences between the structure and function of arteries and veins?

Arteries are blood vessels that carry blood away from the heart. They have thicker walls than veins in order to cope with far higher blood pressure levels. Arteries also have a thicker layer of smooth muscle than veins, allowing them to be more elastic and therefore cope with the changing volume of blood caused by each heartbeat. Arteries have a narrower lumen (the space through which blood flows), in order to keep the blood at a higher pressure. Veins are the blood vessels that carry blood back towards the heart. They have thinner walls, and thinner layers of smooth muscle than arteries, as the blood pressure within them is lower. Veins also contain valves, which are used to prevent the backflow of blood through the lower pressured venous circulation. Veins have a wider lumen than arteries.