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Adaptations of Small Intestine for Absorption

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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. ...read more.


These secrete intestinal juice to help in digestion. (refer to T6.2) 2. Summary of Absorption 1. Simple sugars, amino acids, vitamins & minerals l (diffusion) blood capillaries of villi l hepatic portal vein l liver --- hepatic vein --- heart 2a. Soluble glycerol l (diffusion) epithelium of villi 2b. Fatty acids + bile salts l soluble soaps l (diffusion) epithelium of villi 2c. In epithelium: glycerol + soluble soaps l fat globules l lacteal --- lymphatic sys. -- heart 3. Fate of absorbed simple sugars / glucose Tissue Respiration - to release energy. Excess glucose - stored in liver & muscles as glycogen 4. ...read more.


b. regulation of blood glucose concentration. Inter-conversions of glucose & glycogen to maintain glucose conc. at 70-90 mg/100 cm3 of blood. c. Deamination of excess amino acids to non-toxic urea. d. Utilisation of fats. The live is able to convert absorbed fats into forms that can be readily oxidsed or stored in adipose tissues. Other Functions of Liver (not associated with digestion) e. Blood storage. Can store up a considerable volume of blood that can be release into the circulation in times of emergency. f. Formation of plasma proteins for blood clotting. g. Production of heparin to prevent clotting of blood in the vessels. h. Iron storage - from breaking down of haemoglobin. i. Vit A & D storage. j. Detoxication. k. Heat production. 2002 / Lessons / N_T6.3 Absorption 08/03/2002 1 ...read more.

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Here's what a teacher thought of this essay

3 star(s)

The first section about the structure of villi etc is good.

The section on absorption is much weaker and is the main reason this piece of work does not gain a 4 star rating. Little A level standard knowledge or understanding are shown and it lacks detail.

Marked by teacher Adam Roberts 08/01/2013

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