Glossary

Veins: Veins are vessels that convey blood toward the heart. The pulmonary veins carry oxygenated blood from the lungs to the heart; all other veins carry oxygenated blood from all the other parts of the body to the heart. Veins and arteries have walls composed of three layers: 1. Tunica intima: composed of a single layer of endothelial cells 2. Tunica media: made of smooth muscle 3. Tunica adventitia: composed of white fibrous connective tissue