What are the various enzymatic types of glandular secretions in our gut helping digestion of food? What is the nature of end products obtained after complete digestion of food?

Question

Philoid · Accepted Answer

The various enzymatic types of glandular secretions in our gut helping digestion of food are as follows:

- Secretion from gastric glands: gastric juice is secreted in stomach which contains HCl and Pepsin enzyme. Gastric juice contains hydrochloric acid and proenzyme - pepsinogen and prorennin. HCl maintains a strongly acidic pH which converts these proenzymes into pepsin. Rennin is secreted in infants that helps in digestion of milk.

- Secretions in Liver: here bile juice is secreted. Bile helps in emulsification of fats. Bile also provides alkaline medium which is useful for working of enzymes present in the small intestine.

- Secretions from pancreas: here pancreatic juice is secreted. The pancreatic juice contains inactive enzymes trypsinogen, chymotrypsinogen, procarboxypeptidases, amylases, lipases and nucleases. Trypsinogen is activated by an enzyme, enterokinase, (secreted by the intestinal mucosa) into active trypsin, which in turn activates the other enzymes in the pancreatic juice. Amylase digests carbohydrates and trypsin/chymotrypsin digests protein.

Pancreatic juice and bile are released through the hepato-pancreatic duct. The bile released into the duodenum contains bile pigments (billirubin and billiverdin), bile salts, cholesterol and phospholipids but no enzymes. Bile also activates lipases.

- Secretions from small intestine: The secretions of the brush border cells of the mucosa along with the secretions of the goblet cells constitute the intestinal juice or succus entericus. This juice contains a variety of enzymes like disaccharidases (e.g., maltase), dipeptidases, lipases, nucleosidases, etc. The mucus along with the bicarbonates from the pancreas protects the intestinal mucosa from acid as well as provide an alkaline medium (pH 7.8) for enzymatic activities.

The nature of end products obtained after complete digestion of food is as follows:

Dipeptides Amino acids

Maltose Glucose + Glucose

Lactose Glucose + Fructose

Nucleotides Nucleosides Sugars + bases

Di and monoglycerides Fatty acids + Glycerols