ANIMAL PHYSIOLOGY
HUMAN CIRCULATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Thin walls so short diffusion pathway
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Lots of capillaries provide a large surface area for diffusion
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Constant blood supply maintains a concentration gradient
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Small cross-sectional area slows blood flow to allow more time for exchange
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Detailed explanation-1: -Capillaries have walls only one endothelial cell thick, meaning their walls are very thin. This makes them well adapted for gas exchange, as substances only have to diffuse over a short distance.
Detailed explanation-2: -For example, a capillary is microscopically thin to allow gases to exchange, the arteries are tough and flexible to cope with high pressure blood flow and the veins contain valves to prevent the blood from travelling backwards when at low pressure.
Detailed explanation-3: -Capillaries: These tiny blood vessels have thin walls. Oxygen and nutrients from the blood can move through the walls and get into organs and tissues. The capillaries also take waste products away from your tissues. Capillaries are where oxygen and nutrients are exchanged for carbon dioxide and waste.