Question

How is the wall of the small intestine adapted for performing the function of absorption of food?

Answer 1

Small intestine:

1. The small intestine is where many nutrients, minerals, and water are absorbed.
2. It secretes digestive juices that aid in food digestion and absorption.
3. The small intestine is divided into three sections: the duodenum, the presence of small finger-like projections called villi in the duodenum, aids in food absorption.
4. The jejunum has an enterocyte cell lining that digests minor nutrients with the help of digestive enzymes.
5. The ileum aids in absorbing bile salts, vitamin B12, and other byproducts.

Absorption process in the small intestine:

1. The small intestine is the primary absorption site.
2. The internal surface area of the small intestine is significantly increased for this purpose by its enormous length, folds, villi, and microvilli.
3. The folds are a close-set longitudinal or transverse projection of the intestine's mucosa into the lumen.
4. The villi are numerous small, finger-shaped mucosal projections.
5. Each villus contains numerous blood capillaries and a lymph vessel that has been twisted and shortened to speed up the absorption by causing blood and lymph circulation.
6. The movement of villi is accelerated by villikinin, a hormone secreted by the intestinal mucosa in response to the presence of food in the intestine.
7. Mechanical mixing of food by muscular contraction of the intestinal wall aids absorption by constantly renewing the fluid in direct contact with the porous surface.
8. The hormones cholecystokinin and secretin are produced in the small intestine, together with digestive enzymes and juices.
9. They result in food absorption and digestion.

Intestinal Villi