In the end of the esophagus is a large J-shaped organ called the stomach,lies in the upper left side of our body. Foods in the esophagus enters the stomach through the opening called cardiac sphincter. The cardiac sphincter closes and opens allowing the flow of foods to enter from the esophagus to the stomach.

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Inside the stomach foods are further digested mechanically. The muscles in the stomach contracts and brings about twisting, squeezing, churning and mixing the foods.

There are gastric glands within the thick and wrinkled membrane in the linings of the stomach. Within the walls of these glands, secretory cells are lined. The cell secrets an enzymes, another secrets hydrochloric acid and water, other secrets mucus. The combination of the enzyme,hydrochloric acid, water, and mucus forms the gastric juice which helps in chemical digestion of foods.

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The enzymes that are produced in the stomach mostly breakdown proteins ( they are also called protease ). Pepsin was considered as the main protease. It breaks down proteins into polypeptides in the presence of acid.

The hydrochloric acid that are produce in the stomach are also considered as  strong substance. It destroys bacteria and helps to break up connective tissues and cell membranes on foods inside the stomach.

It takes two to three hours for the food to remain in the stomach. Within this hours, the muscles of the stomach chums the foods. The stomach separates the food particles and mixed them with different secretions.

When digestion is completed, food (now called chyme) moves into small intestines.

The pyloric valve (the valve at the intestinal end) opens and closes several times. Foods moves going into the small intestine every time the valve opened.

When all the foods finally goes into the small intestine, the stomach is relieve and begins to rest.

The stomach starts contracting again after several hours without the presence of food. This time, the sensation of hunger is felt.

From the stomach, the foods or chyme goes into the small intestine,there, it faces another stage of digestion