Question

Describe in detail the process of the digestion in the small intestine.

Answer 1

The small intestine can be divided into three sections as, duodenum, jejunum, and ileum. Duodenum is the first section, jejunum is the middle section and the ileum is the final section. The process of digestion occurring in these sections is as follows.

1. The food from the stomach reaches the duodenum. The bile juice and pancreatic juice are released in the duodenum. The trypsinogen present in pancreatic juice is activated by enterokinase to form trypsin. Trypsin then activates the chymotrypsinogen to form chymotrypsin. These enzymes break down proteins into dipeptides. Dipeptides are broken into amino acids by dipeptidases. Fats are hydrolyzed with the help of bile and lipases. Amylase helps in the digestion of carbohydrates.
   
2. The digested food moves to the jejunum where most of the food absorption will occur. This portion has villi present which is richly supplied with blood vessels and lymph vessels. The blood vessels absorb all the nutrients while lymph vessel absorbs the fats.
3. The remaining nutrients are absorbed in the ileum as the undigested food is transferred on to the large intestine through the ileum.