Blood Vessels - Arteries and Veins
Blood vessels are a network of branched tubes that transport blood. There are three types of blood vessels namely arteries, veins and capillaries
Arteries: They are thick and elastic vessels that carry blood away from the heart to various organs of the body. All arteries carry oxygenated blood except the pulmonary artery which carry deoxygenated blood to the lungs.
Veins: Veins are thin and non-elastic vessels that transport blood to the heart from the different organs. All veins carry deoxygenated blood except the pulmonary vein which carry oxygenated blood from the lungs to the heart.
Capillaries: Capillaries are narrow tubes formed by branching of arterioles which then unite to form the venules and veins. They are about 8 µm in diameter. Capillaries are formed of single layer of endothelial cells.