Does the stomach perform both mechanical and chemical digestive processes?

Yes, the stomach performs both mechanical and chemical digestive processes.

Mechanical digestion in the stomach involves the physical breakdown of food into smaller particles. This is accomplished through the muscular contractions of the stomach walls, which churn and mix the food with gastric juices. The stomach also contains ridges called rugae, which help to increase the surface area of the stomach and facilitate the mixing process.

Chemical digestion in the stomach involves the breakdown of food by enzymes. The most important enzyme in the stomach is pepsin, which breaks down proteins into smaller peptides. Pepsin is activated by the acidic environment of the stomach, which is created by the secretion of hydrochloric acid (HCl) by the stomach lining. HCl also helps to kill bacteria and other microorganisms that may be present in the food.

The combined effects of mechanical and chemical digestion in the stomach help to break down food into a semi-liquid substance called chyme, which is then passed to the small intestine for further digestion and absorption.