Body's Vascular System

The body's blood vessels or vascular system consists of the heart (a pump), arteries that carry blood away from the heart to the distant parts of the body, and veins that bring the blood back to the heart and then on to the lungs. Along the way, blood passes through various cells collecting or unloading oxygen, nutrients or waste products, depending on the blood vessel and/or organ that it passes through. The arteries rely on the driving force of the heart to push blood along to various parts of the body, while blood is pushed along the veins by a combination of muscle contractions and the action of one-way valves that prevent blood from falling backwards.