Blood Vessals

Arteries consist of three layers, the first being a smooth endothlial layer, the second a thick layer of smooth muscle and elastic tissue and the third a tough layer made up of fibrous tissue. Arteries also have a small lumen in comparison to that of a vien. Arteries carry blood away from the heart, the further the artery is from the heart the smaller it becomes. A small artery is called an ateriole and delivers blood to other systems in the body.

Arteries spring back very quickly and this ensures that the blood continues to flow efficiently as the blood travels with the aid of the arteries physically contracting around them and forcing it in the right direction. For this reason arteries need no valves, the blood is moving too quickly at too much of a high pressure to go backwards.