Question

Write names and functions of enzymes present in the gastric juice of humans?

Answer 1

Gastric juice is the digestive fluid which is formed by the gastric glands present in the stomach. Gastric juice contains Hydrochloric acid, potassium chloride, sodium chloride and enzymes which play key roles in the digestion of food (especially proteins).

Complete answer:
The mucosa of the stomach has gastric glands. Gastric glands have three types of cells:

Mucous neck cells: These cells secrete mucus.
Peptic or chief cells: These cells secrete the proenzyme pepsinogen.
Parietal or oxyntic cells: These cells secrete HCl and intrinsic factors.
Gastric juice of human contains three enzymes:
Pepsin: This enzyme is present in the inactive form pepsinogen. It becomes active when it comes in contact with HCl and converts into pepsin. Pepsin converts proteins into proteoses and peptones (peptides).
Rennin: It is a proteolytic enzyme found in the gastric juice of infants which helps in the digestion of milk protein Casein. It converts casein into Ca-paracaseinate.
Gastric lipases: This enzyme helps in the digestion of fats. It converts fats into glycerol and fatty acids.
The pH of the gastric juice is 1.8 which is acidic in medium. Acidic medium of the stomach is optimal for activation of enzyme pepsin.
HCl of gastric juice converts $F{e^{3 + }}$ into $F{e^{2 + }}$ which makes the absorption of iron easy. The mucus and bicarbonates present in the gastric juice protects the mucosal epithelium from excoriation by the hydrochloric acid.

Note: The gastrin hormone is a peptide hormone released by the stomach which stimulates the gastric gland to secrete and release the gastric juice. Chyme is the thick acidic mixture of gastric juice and semi digested food formed in the stomach.