Question

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?

Answer 1

Enzymatic types of glandular secretions in our gut:

a. Salivary glands: Saliva is mainly produced by three pairs of salivary glands, the parotids (cheek), the sub-maxillary/sub-mandibular (lower jaw) and the sublingual (below the tongue). These glands situated just outside the buccal cavity secrete salivary juice into the buccal cavity.

b. Gastric glands: The mucosa of the stomach has gastric glands. Gastric glands have three major types of cells namely

(i) Mucus neck cells which secrete mucus;

(ii) Peptic or chief cells which secrete the proenzyme pepsinogen; and

(iii) Parietal or oxyntic cells secrete HC1 and intrinsic factors (factor essential for the absorption of vitamin B12).

c. The bile, pancreatic juice and intestinal juice are the secretions released into the small intestine. Pancreatic juice and bile are released through the hepato-pancreatic duct. 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. The bile released into the duodenum contains bile pigments (bilirubin and biliverdin), bile salts, cholesterol and phospholipids but no enzymes.