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Adaptations of Small Intestine for Absorption
- Essay length: 490 words
- Submitted: 15/08/2003
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Marked by teacher:
Adam Roberts
Teacher essay summary
***
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
The first 200 words of this essay...
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 reach the capillaries & lacteals.
*There are intestinal glands between bases of villi. These secrete intestinal juice to help in digestion. (refer to T6.2)
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MbT essay summary
***
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.
