Both mechanical and chemical digestion occur in the stomach. Explain how this organ performs chemical digestion

Answer 1

The stomach performs chemical digestion through the secretion of gastric juice, which is produced by specialized cells in the lining of the stomach called gastric glands. Gastric juice is a mixture of hydrochloric acid, pepsinogen, and mucus.

1. Hydrochloric Acid: The stomach secretes hydrochloric acid, which helps to lower the pH of the stomach and create an acidic environment. The acidity of the stomach aids in the breakdown of food and activates pepsinogen into pepsin.

2. Pepsinogen: Gastric glands also secrete pepsinogen, an inactive enzyme. When hydrochloric acid comes into contact with pepsinogen, it converts it into its active form called pepsin. Pepsin is a protease enzyme that begins the breakdown of proteins present in the food. It breaks the proteins down into smaller peptide chains.

3. Mucus: The stomach lining also secretes mucus that coats the inner surface of the stomach. This mucus acts as a protective layer and helps prevent the acidic gastric juice from damaging the stomach lining.

Together, hydrochloric acid, pepsinogen, and mucus in the gastric juice work to break down proteins into smaller peptide chains through chemical digestion. Additionally, the churning motion of the stomach helps to mix the food thoroughly with gastric juice, further aiding in the chemical digestion process.