BLOOD CARDIOVASCULAR SYSTEM LYMPHOID ORGANS
CARDIOVASCULAR SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Which best explains why capillary walls are so thin?
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because they do not need to pump blood
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because they are found only in the smallest organs and tissues
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because they maximize diffusion of nutrients
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because blood only travels through them slowly
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Explanation:
Detailed explanation-1: -Gas Exchange The capillaries optimise the diffusion rate by receiving a constant blood supply. They also have an average membrane thickness of only 0.6 micrometres and form a network of capillaries over the alveoli.
Detailed explanation-2: -Elsewhere in the body, oxygen and other nutrients diffuse from blood in the capillaries to the tissues they supply. The capillaries absorb carbon dioxide and other waste products from the tissues and then flow the deoxygenated blood into the veins.
Detailed explanation-3: -Capillaries are thin-walled vessels composed of a single endothelial layer. Because of the thin walls of the capillary, the exchange of nutrients and metabolites occurs primarily via diffusion.
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