Digestion And Absorption

The crypts of Lieberkuhn are simple, tubular glands which occur throughout the small intestine between the villi and secrete enzymes as well as mucus. The crypts have two types of cells at their base:
(a) Paneth cells : They are found particularly in the duodenum, in the bottom of crypts of. Lieberkuhn. These cells are rich in zinc and ? contain acidophilic granules. They probably secrete lysozyme.
(b) Argentaffin cells: They are also known as entero-chromaffin cells and are fairly common in duodenum, located among epithelial cells lining the crypts of Lieberkuhn. Argentaffin cells secrete secretin hormone and 5-hydroxytryptamine (5-HT).

The sources of proteins in our diet are cereals, pulses, oil seeds and nuts, meat, fish, eggs, milk, cheese, leafy vegetables, roots and tubers, fruits, soyabean, groundnut, peas etc. Soyabean is the richest source of protein. It contains all the essential amino acids, which cannot be synthesized by our body.

In the presence of enterokinase (a protease . of intestinal juice), inactive trypsinogen is converted to active trypsin. Trypsin then activates chymotrypsinogen and procarboxypeptidase into chymotrypsin and carboxypeptidas~ respectively. This enables simultaneous action of all pancreatic proteases for a rapid digestion of proteins.