Small Intestine

Nutrition in animals of Class 7

Small Intestine length

It is a coiled and narrow tube having 3 regions: duodenum, jejunum, and ileum. it is six to seven metres long and 2.5 cm in diameter.


Duodenum is the initial part of the small intestine. it is ‘C’ shaped, into which the bile and the pancreatic ducts open through a common bile duct.

  • Duodenal gland : Present mainly in duodenum; secretes mucous.


The part next to the duodenum is jejunum. It is a short region of small intestine before ileum.


It is the longest part of the small intestine. The major part of the process of digestion of food takes place in the small intestine. The inner lining of the small intestine is produced into a number of finger-like projections called villi. Each villus is covered by a single layer of epithelium and contains blood capillaries and a small lymph vessel

Highly organised system of blood capillaries up to villi for the transportation of absorbed food.

The villi increase the surface area for absorption. In between the villi are glandular pits having glands which secrete the digestive enzymes into the lumen of the intestine.

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