Explain how the stomach performs chemical digestion

Answer 1

The stomach performs chemical digestion by secreting gastric juice that contains various enzymes and acid.

The first step in chemical digestion occurs when food enters the stomach. The stomach walls produce gastric juice, which is a mixture of hydrochloric acid, enzymes, and mucus. The enzyme pepsinogen is also released, which is later activated to pepsin by the acidic environment of the stomach.

Hydrochloric acid plays several important roles in chemical digestion. Firstly, it creates an acidic environment in the stomach that helps in the breakdown of complex proteins into simpler peptides and amino acids. The acidic pH also denatures proteins, making them more accessible to the action of pepsin and other enzymes.

Pepsin is a protease enzyme that specifically breaks down proteins. It hydrolyzes peptide bonds between amino acids, breaking proteins into smaller polypeptides and individual amino acids. Pepsin works optimally in the acidic pH of the stomach.

Additionally, gastric lipase is released in small amounts in the stomach, which helps in the digestion of dietary fats.

The stomach walls also produce mucus, which helps to protect the stomach lining from the corrosive effects of the acid and pepsin.

The muscular contractions of the stomach, known as peristalsis, help to mix the food with gastric juice and facilitate the breakdown of food particles. This creates a semi-liquid mixture called chyme.

Overall, the stomach performs chemical digestion by secreting gastric juice containing enzymes and acid, facilitating the breakdown of proteins into peptides and amino acids. This prepares the partially digested food for further digestion and absorption in the small intestine.