HUMAN PHYSIOLOGY
DIGESTION AND ABSORPTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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It maintains a high concentration gradient
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It creates a long diffusion path
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It enables active transport
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It transports fats around the body
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Detailed explanation-1: -The capillaries have several functions in the villi, they carry the absorbed nutrients such as proteins and carbohydrates away from the villi but also delivers oxygen to the microvilli so that they can perform cell respiration.
Detailed explanation-2: -Capillaries are the site at which exchange of oxygen, carbon dioxide and nutrients takes place. The structure of capillaries makes them very well suited for this function. As capillaries are only one cell thick and have very thin permeable walls this means that substances can diffuse out of them very easily.
Detailed explanation-3: -The villi in the small intestine provide a large surface area with an extensive network of blood capillaries. This makes the villi well adapted to absorb the products of digestion by diffusion and active transport.
Detailed explanation-4: -Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries ( amino acids and carbohydrates) and lacteals (lipids).