2. Arteries The arteries have thick, elastic, muscular walls and carry blood under high pressure away from your heart.
3. Veins Another type of vessel is called veins. They have thinner walls, and valves that prevent the blood from flowing backwards. Veins carry blood to the heart.
4. Capillaries The most numerous and smallest blood vessels are called capillaries. Your body contains about 1000000 km of capillaries, which penetrate almost every tissue. No cell is very far away from one. Capillaries are very important blood vessels because they carry materials such as oxygen nutrients to the cells and remove wastes including carbon dioxide.
5. Heart The heart is a muscular organ that pumps blood around the body for the circulatory system.
