Give reason for the following: Mucus is secreted along with HCl in stomach.

Gastric acid, gastric juice or stomach acid, is a digestive fluid formed in the stomach and is composed of hydrochloric acid (HCl), potassium chloride (KCl) and sodium chloride (NaCl). The acid plays a key role in digestion of proteins, by activating digestive enzymes, and making ingested proteins unravel so that digestive enzymes break down the long chains of amino acids. Gastric acid is produced by cells in the lining of the stomach, which are coupled in feedback systems to increase acid production when needed.

• Mucus is secreted along with the hydrochloric acid to protect the sensitive layers of the stomach. Hydrochloric acid is a very strong acid it can dissolve even some metals in it so to save our stomach layer getting burned off the mucus is secreted along with HCl.

• The highly acidic environment in the stomach lumen causes proteins from food to lose their characteristic folded structure (or denature). This exposes the protein's peptide bonds. The gastric chief cells of the stomach secrete enzymes for protein breakdown (inactive pepsinogen, and in infancy rennin). Hydrochloric acid activates pepsinogen into the enzyme pepsin, which then helps digestion by breaking the bonds linking amino acids, a process known as proteolysis.

• In addition, many microorganisms have their growth inhibited by such an acidic environment, which is helpful to prevent infection.

• It also helps in the movement of food downwards to the small intestine.

• It also plays a major role in digestion of food