Blood Vessels
Blood vessels are tube-like structures that carry blood to all parts of the body. There are three main types of blood vessels in the body.
Arteries
Arteries carry oxygen-rich blood from the heart to the rest of the body. They have thick, elastic walls. They are found deep inside the body and are not usually seen under the skin. The aorta is the largest artery in the body. The carotid artery supplies blood to the head.
Veins
Veins carry oxygen-poor blood from the rest of the body to the heart. They have thinner walls than the arteries. They are located nearer to the surface of the skin and thus some of them can be seen. The superior vena cava carries blood from the head, neck, arms and chest, and the inferior vena cava carries blood from the abdomen and legs.
Capillaries
These blood vessels connect the arteries and the veins. They have thin walls, about one cell thick. This helps the capillaries take oxygen to every cell and collect waste from every cell.
