What is digestion in stomach. In biology

What is digestion in stomach. In biology:- presence of gastric folds in the stomach makes the stomach very elastic and distensible, therefore it acts like a silo. when food reaches stomach its muscles start relaxing leading to its distension. It is called receptive relaxation. Due to this food accumulates in the stomach and remains there for 2-5 hours. stomach also exhibits two types of digestion- mechanical and chemical.

Mechanical digestion:-

Peristaltic movement start in the stomach as soon as food reaches there. These movement are slow but intense. Due to these movement the gastric juice mixes thoroughly with food and the food is cinverted into a thin pulp. This acidic pulp is called chyme. Such movements of the stomach are called churning movements.

Chemical digestion:-

The glands situated in the wall of gastric mucosa secrete hormone gastrin as the food reaches into the stomach. This hormone mixes with blood and stimulates the gastric activity. This hormone stimulates and regulates the secretion of gastric juice form gastric glands and gastric movements. similarly the mast cells presents in the connective tissue of the mucosa of stomach secrete histamine. Histamine is produced by the decarboxylation of amino acid histidine. Histamine is also found in certain food stuffs. Histamine also stimulates secretion of gastric juice from gastric glands.

Gastric juice:-

The gastric glands of the stomach produce approximately 1-1.5 litres of colourless and thin gastric juice daily. It has a Specific gravity of 1.002- 1.006 and pH 0.9-1.5. This pH in the food filled stomach becomes 1.5 to 2.5. Gastric juice contain 97-99 percent water glycoprotein mucin, Hydrochloride acid (HCl), enzyme pepsinogen, lipase, rennin in infants and many types of ions. different components of gastric juice have following functions:-

  1. mucin
  2. Hydrochloric acid
  3. pepsinogen
  4. Rennin
  5. Lipase