question_answer 101)

  Why do veins have thin walls as compared to arteries?

Answer:

                  Arteries are thick wailed blood vessels which carry blood from heart to all parts of body. They have thick wails because blood emerges from the heart under high pressure. In comparison, veins are thin walled blood vessels which carry deoxygenated blood from all parts of the body back to the heart. They do not need thick walls because blood flowing through them is no longer under high pressure. Instead, they have valves which prevent the backflow of blood.