Function of the Stomach in Physical Digestion

Mixing and Churning

When food enters the stomach from the esophagus, the stomach muscles contract and relax in a coordinated manner. This allows mixing, grinding and churning action to thoroughly mix the food with gastric juices, creating a semi-liquid mixture called chyme. Chyme is the liquid paste version of the food.

Mechanical Breakdown

As the stomach muscles contract and squeeze the chyme, they physically break down the larger food particles into smaller fragments. This process increases the surface area of the food, preparing it for more efficient chemical digestion by enzymes.

Acidic Environment

Stomach secretes hydrochloric acid (HCl) and other gastric juices. It provides optimum pH for the enzymes pepsin (digest proteins) and kills bacteria. The stomach lining contains specialized cells that secrete this acid.

Storing and Regulating Release 

In addition to its mechanical functions, the stomach also serves as a temporary storage reservoir for food. After eating a meal, the stomach slowly releases the chyme into the small intestine in a controlled manner. This regulated release ensures that the small intestine can handle the digestion and absorption of nutrients at an optimal rate.