The superior vena cava is the large vein that brings blood from the head and arms to the heart, and the inferior vena cava brings blood from the abdomen and legs into the heart. This vast system of blood vessels -arteries, veins, and capillaries - is over 60,000 miles long.
Blood vessels form the living system of tubes that carry blood both to and from the heart. All cells in the body need oxygen and the vital nutrients found in blood. Without oxygen and these nutrients, the cells will die. The heart helps to provide oxygen and nutrients to the body’s tissues and organs by ensuring a rich supply of blood. A blood vessel's main function is to transport blood around the body. Blood vessels also play a role in controlling your blood pressure.
Blood vessels are found throughout the body. There are five main types of blood vessels: arteries, arterioles, capillaries, venules and veins.
Arteries carry blood away from the heart to other organs. They can vary in size. The largest arteries have special elastic fibres in their walls. This helps to complement the work of the heart, by squeezing blood along when heart muscle relaxes. Arteries also respond to signals from our nervous system, either constricting (tightening) or dilating (relaxing).
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