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Human Body
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80 that the absorption of nutrients can proceed inost efficiently. The absorption of valuable nutrients results from efficient enzyme action and the way with which the intestinal lining absorbs them from the cavity of the intestine. Perhaps the most important components of the intestine are millions of villi-tiny fingerlike projections on its walls. These are the working structures of the small intestine in its function of absorption of digested nutrients. Each villus. contains a network of capillaries, and a lymph vessel. (See, figure). Nutrients pass through into the small blood-vessels which run into larger ones and eventually into the hepatic vein which leads to the liver, where breakdown continues, before final delivery to the other cells of the body. Once absorbed by the body, the broken-down substances provide the raw materials for the building of longer and more complicated molecules which are better suited to the needs of the body.
SMALL INTESTINE Villi
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brush border
glycocalx
nucleus
capillaries
the living epithelium
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lacteal.
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COOTD
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intestinal
gland
Vein
The end products of digestion which are absorbed include glucose (from carbohydrates), amino-acids (from proteins) and a milky fatty emulsion. They are put into circulation-glucose and amino-acids via the blood-stream and fatty emulsion via the lymphatic system. Over and above these three main nutrients, the following are also extracted and made available for bodily functions :
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