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. Can you explain why?

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Solution

Blood in the arteries, after being pumped by the heart, is under a much higher pressure than blood in veins.

[1 Mark]

So the internal pressure of the blood in the vessel far outweighs the risk of a back flow. Hence valves are absent in arteries.

[1 Mark]

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Similar questions

Differentiate between each of the following pairs with reference to the aspect asked within brackets:
(a) Erythrocytes and leucocyte (function)
(b) Artery and vein (direction of blood flow)
(c) Artery and vein (the type of blood primarily flowing through)
(d) Tricuspid and bicuspid valves (location).

Q. State the true statements of the following:

(1)

Blood flowing in arteries is without high pressure.

(2)

Blood flowing in veins is without high pressure.

(3)

Veins have valves opening towards heart.

(4)

Arteries have valves opening towards heart.

The valves which allow blood to flow from the ventricles into the arteries and not in the opposite direction are:

Q. Fill in each blank with the best choice from the words in brackets
Arteries have no valves. Nevertheless, veins do have valves, which prevent backflowof blood. The colour of blood provides yet another way in which arteries and veins are not ________________ (alike/same).

Veins have valves to prevent the backflow of blood because the blood in veins flow ________.

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Arteries

Standard VII Biology

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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. Can you explain why?

Blood in the arteries, after being pumped by the heart, is under a much higher pressure than blood in veins. [1 Mark] So the internal pressure of the blood in the vessel far outweighs the risk of a back flow. Hence valves are absent in arteries. [1 Mark]

Blood in the arteries, after being pumped by the heart, is under a much higher pressure than blood in veins.

[1 Mark]

So the internal pressure of the blood in the vessel far outweighs the risk of a back flow. Hence valves are absent in arteries.

[1 Mark]