QS Study

Why does Stomach not Digest itself?

The stomach is a reservoir of food particles, where digestion begins. It is the internal organ in which the major part of the digestion of food occurs, being (in humans and many mammals) a pear-shaped enlargement of the alimentary canal linking the esophagus to the small intestine. The stomach normally does not digest itself because of a mechanism which regulates gastric secretion. The digestive juices in the stomach consist mainly of hydrochloric acid (HCI), a strongly acidic solution as you saw on the PH Scale. Enzymes, which make up part of the digestive juices are also secreted by the stomach wall, from glands with no mucus barrier.

The stomach does not digest itself because –

  • Gastric mucosal glands of the stomach secret mucous which form a protective gastric mucosa barrier. As a result, HCl and pepsin do not come in contact with the mucous membrane of the stomach.
  • HCO3in gastric juice neutralizes the HCl. So it saves gastric mucosa.
  • Presence of antipepsin to counteract peptic digestion.
  • Production of NH3 by urease locally that is doubtful neutralizer of HCl.