Prime objective of this lecture is to present on Blood Vessels. Here briefly describe and compare the structure and function of: Arteries, Veins and Capillaries. The blood vessels consist of arteries, arterioles, capillaries, venules, and veins. All blood is carried in these vessels. Blood leaves the heart through arteries, which in turn give way to arterioles and then capilliaries where the oxygen is delivered and exchanged for carbon dioxide. The capillaries then become larger venules and then veins which then deliver the blood back to the heart.