What substances are contained in gastric juice? What are their functions?

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Gastric juice contains three substances: hydrochloric acid, enzyme pepsin, and mucus. The objectives are to break down proteins into peptones, stop the release of hydrochloric acid, and eliminate bacteria.

Functions of Gastric Juice

  • The medium is made acidic in the stomach using hydrochloric acid, which helps the enzyme pepsin function and, if any germs are present, kills them.
  • Proteins are broken down by the enzyme pepsin and turned into peptones.
  • The mucus helps shield the stomach wall from hydrochloric acid discharges produced by the stomach itself.


  • Gastric juice contains the digesting enzyme pepsin, which breaks down proteins into smaller peptides. One of the essential digestive enzymes present in both humans and other animals, it is an endopeptidase that is secreted in the stomach lining by the gastric main cells.
  • The enzyme has a catalytic aspartate in its active site and is an aspartic protease. Trypsin and chymotrypsin are the other two main endopeptidases discovered in the human digestive tract. Exopeptidases are also present in the digestive system and cleave the terminal amino acids from proteins in addition to the peptide bonds of proteins that are broken by endopeptidases.
  • Together, the endopeptidases and exopeptidases break down the protein into peptides and amino acids that the body can quickly absorb.


What substances are contained in gastric juice? What are their functions?

The substances present in gastric juice are mucus, pepsin enzyme, and hydrochloric acid. The functions are to digest proteins and convert to peptones, prevent hydrochloric acid secretion, and to kill germs.

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