Question

Describe in detail the process of digestion which takes place in the small intestine.

Answer 1

The small intestine has a major function of absorbing the nutrients from the digested food but complete digestion of food also takes place in the small intestine. Many enzymes from the pancreas, gallbladder, etc are released into the small intestine and help in digestion.

The digestive processes that take place are:

1. Proteins are broken down into small peptides and amino acids through the action of proteases. Proteases such as trypsin and chymotrypsin break down the polypeptide into small peptides by breaking down their peptide linkages.

2. Lipids are broken down into fatty acids and glycerol. Pancreatic lipase breaks down fats into triglycerides and monoglycerides. The digestion of lipids is added by bile juice and bile salts which help in emulsification of fats.

3. Carbohydrates are broken down into oligosaccharides, disaccharide or monosaccharides. Pancreatic amylase breaks down big carbohydrates such as starch into oligosaccharides.

These digested nutrients are then absorbed into the blood through projections of the small intestine known as villi.