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Adaptations of Small Intestine for Absorption
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| Submitted: Fri Aug 15 2003
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MARIS STELLA HIGH SCHOOL SEC 3 PURE BIOLOGY Topic 6 Nutrition in Mammals T6.3 Absorption of Food & Functions of the Liver 1. Adaptations of Small Intestine for Absorption It is very LONG, about 5-6 m. This gives plenty of time for digestion to be completed, and fordigested food to be absorbed as it passes through. It has very FOLDED surface. The inner wall is thrown into numerous folds & furrows. Thus the surface area for absorption is greatly enlarged. It has minute finger-like projections (about 1 mm long) called villi covering the whole internal surface of the small intestine. (Each square millimemtre of surface has about 20-40 villi and there are about 5 million in the ileum.) Each villus bears even smaller projections, microvilli. The villi & microvilli further increase surface area for absorption. Villi contain network of blood capillaries & lacteals for transporting digested, absorbed food away. One-cell thick epithelium. The digested food can easily cross the wall to...
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