Updated By: LatestGKGS Desk
Digestive System: Digestion of protein in stomach and role of pancreatic juice
The procedure of digestion and the role of enzymes in protein digestion
The gastric glands of the stomach secrete gastric juice that contains HCl and proenzymes – pepsinogen and prorenin.
The proenzyme pepsinogen, on exposure to HCl, gets converted into the active enzyme pepsin, the proteolytic enzyme of the stomach.
The pepsin converts proteins into proteoses and peptones (peptides). Prorenin is found in the gastric juice of infants and is activated by pepsin into active rennin. It helps in the digestion of milk protein casein.
The pancreatic juice contains inactive enzymes – trypsinogen, chymotrypsinogen, procarboxypeptidases.
Trypsinogen is acti¬vated by an enzyme enterokinase, (secreted by the intestinal mucosa) into active trypsin, which in turn activates the other enzymes of the pancreatic juice. Proteins, proteases, and peptones (partially hydrolyzed proteins) in the chyme reaching the intestine are acted upon by these proteolytic enzymes of pancreatic juice.
Chymotrypsin is a proteolytic enzyme of pancreatic juice secreted by an exocrine part of the pancreas. It helps in the digestion of proteins. It converts proteins, peptones, and proteases into oligopeptides and dipeptides. Two other proteolytic enzymes present in pancreatic juice are trypsinogen and procarboxypeptidase.
The digestion of carbohydrates does not occur in the stomach because gastric juice itself has no carbohydrate.
In the small intestine, the food mixes with two juices, pancreatic juice, and intestinal juice. Pancreatic juice contains a carbohydrase named pancreatic amylase. This enzyme hydrolyzes more starch and glycogen.
