Question

Give reasons for the following.
Arteries have thick walls.

Answer 1

Hint: The main function of the artery is to transport blood from the heart to all parts of the body. The blood in the arteries is pumped by the heart under high pressure so that it can reach to every body part.

Complete answer:
Arteries contain muscle and elastic tissue and it transports blood away from the heart. All the arteries have thick walls that enable them to carry blood from the heart to other body parts and the arteries have to withstand a high pressure of blood which is generated by the heart while pushing out the blood. Arteries that are present near the heart have a large number of elastic fibers. Arteries expand when the pressure increases due to the flow of blood and gets relaxed when the pressure decreases i.e. when the heart undergoes relaxation between heartbeats. In order to provide a smoother flow of blood, this expansion and relaxation in the arteries are necessary.

Additional Information:
- Veins, on the contrary, have thin walls and possess a huge irregular lumen (the inner space of the artery where the blood flows).
- The veins transport the blood at relatively low- pressure as compared to the arteries.
- Larger veins have valves that facilitate the unidirectional blood flow towards the heart and prevent the backflow of the blood towards the capillaries.

Note:
- The blood pressure of arteries is 120/80 mm Hg whereas, the blood pressure of the vein is 5- 10mm/Hg. When veins are exposed to high pressure, they become distorted due to relatively thinner walls.