Question

Q1. veins have valves which allow blood to flow only in one direction. arteries do not have valves. yet the blood flows in one direction only. explain why?classs7

Answer 1

the walls of arteries are thick on the other hand the walls of veins are thinner so the pressure exerted by the blood on veins will be more. so the valves present in the veins prevent the back flow of blood (deoxygenated blood).

Answer 2

Veins:

• Arteries are the blood vessels that carry the blood from the heart to the tissues.
• The veins carries the blood from tissues from tissues back to heart. In the human circulatory system there’s no pulling force, there’s only a pushing force from the heart.
• Arteries being attached to heart, have to face a huge force.
• So, backflow of blood in heart is practically impossible.
• But, veins don’t have that force so, blood can flow backwards. So, to prevent that, veins are supplied with valves.

To know:

What are the differences between arteries ,veins and capillaries

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Why the veins are provided with valves? why the arteries have thick wall?

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