In human beings blood transports various substances to all the organs of the body. Blood reaches all the parts of the body through circulatory system, which consists of blood vessels and heart.
Blood vessels
Blood vessels are the tubes through which blood flows in the body. Blood vessels are of three types:
- Veins
- Arteries
- Capillaries
Veins
Veins are thin walled vessels which carry blood from all the parts of the body to heart. They have valves to ensure that the blood flows only towards the heart. Veins are present superficially under the skin. Veins carry deoxygenated blood from all the parts of the body to heart. In veins blood flows smoothly.
Arteries
Arteries are thick walled vessels which carry blood from heart to all the parts of the body. In arteries valves are not present. Arteries are present deep under the skin. Except pulmonary artery, all the arteries carry oxygenated blood from heart to all the parts of the body. In arteries blood flows with jerks.
Capillaries
Capillaries are narrow and thin walled vessels. These are present between arteries and veins. Their function is to exchange food materials, gases, hormones and waster products between blood and body cells.
Test Your Understanding and Answer These Questions:
- What are differences between arteries and veins?
- Name the various blood vessels found in human beings.
- Explain different types of blood vessels found in human beings.
- Point out the differences between arteries, veins and capillaries.