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प्रश्न
Veins have valves that 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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उत्तर
Blood flow in arteries is rapid as the blood in them is under great pressure. Thick elastic walls of arteries are not collapsible and maintain one direction rapid flow.
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संबंधित प्रश्न
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