Describe the structure of arteries, vein and caprillaries and understand their roles.
Arteries take blood away from the heart and the high in the arteries are under high pressure. Blood is delivered to another part of the body.
All veins take blood to the heart. Veins take blood which are under low pressure. Blood in veins returns from the organ.
Between the vein and the artery the blood vessel travels through the organ and where the contents of the organ and exchanged with the blood. The blood vessels in the organ are called carpillary. Substance goes into and out of the cell e.g. Oxygen in, Carbon Dioxide out.