Stomach

This muscular, expandable, J-shaped pouch is responsible for holding and digesting food, as well as removing its nutrients. When food enters the stomach, its muscular walls contract and churn the food with powerful gastric acids, pepsin and other digestive enzymes that kill bacteria and break down proteins. The acid itself does not break down food molecules, rather it provides an optimum pH for the reaction of the enzyme pepsin and kills many microorganisms that are ingested with the food. Result is a creamy substance called chyme, which the stomach stores until it is ready for the small intestine.

Pyloric Sphincter
This ring of muscles forms a valve between the stomach and the small intestine. It opens and closes to control the passage of semi-digested food to the small intestine.

Gastric Folds
These folds on the interior of the stomach help grind and digest food and increase the surface area of the stomach.
Muscular Walls

Three layers of muscles line the stomach walls. When the contract, the muscles squeeze and expand the stomach to churn the food matter.
Greater Curvature
The curve along the lower edge of the stomach is called the greater curvature.

Lesser Curvature
The curve along the upper edge of the stomach is called the lower curvature.