The three main types of blood vessels in the body are arteries, veins and capillaries.
Arteries :
(1) Arteries carry blood away from the heart to body parts.
(2) Arteries carry oxygenated blood, except pulmonary artery, which carries blood from the heart to the lungs.
Veins :
(1) Veins carry blood from body organs to heart.
(2) Veins carry deoxygenated blood, except pulmonary vein, which carries blood from the lungs to the heart.
Capillaries :
(1) These are spread throughout all the tissues.
(2) The capillaries are the smallest blood vessels, which connect arteries with veins.
(3) The walls of capillaries are made of single layer cells. They act as the sites of exchange of substances within the cell.
