How Our Stomach Works

The human body is an astoundingly complex organism. Many intricate biological systems in the body cooperate to support and maintain life. Among these, the digestive system is responsible for helping in breaking down food and assimilating various nutrients. The organs involved in this process are the mouth, esophagus, stomach, small intestine, large intestine, the rectum and anus. This article will focus on the stomach.

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The stomach has three main functions. The first function is to store food and liquid coming from the esophagus. Food enters the stomach through the lower esophageal sphincter, which is located at the top of the stomach. This sphincter opens and closes in response to food passing through the esophagus. It can allow for large volumes of food to enter into the stomach. The upper half of the stomach is responsible for holding the food and liquids until they can be digested.

The second function is to produce gastric juices that turn the food into a usable form. The gastric juices are made of hydrochloric acid and an enzyme called pepsin. Hydrochloric acid is a substance made in the stomach that helps degrade food. The acid also kills hostile microorganisms and maintains the overall level of acidity in the stomach. The walls of the stomach produce mucous that prevents the acid from damaging the stomach itself.

The organ is a muscle that contracts and expands to mix together the food, acid and enzyme into a substance called chyme. This process can take up to several hours. Depending on the type of food ingested, it may remain in the stomach for longer or shorter periods of time. For example, fats remain the longest, while carbohydrates spend the shortest amount of time in the stomach.

The third and final function is to push the digested mixture into the small intestine. The pyloric sphincter, similar to the lower esophageal sphincter, opens to allow the contents of the stomach to pass through. Once the stomach is emptied, digestion proceeds in the small intestine.

Enzymes throughout the body speed up the rate at which biochemical reactions take place. If even a single enzyme is missing or malfunctioning, this can lead to severe or even deadly illnesses. On the molecular level, when food first enters the stomach, it is made up of long strings called macromolecules. These strings are cut into smaller segments by the enzyme pepsin. It is first secreted as pepsinogen, an inactive form of the protein that is transformed into pepsin by the hydrochloric acid.

Aside from pepsin, the other digestive enzymes are produced by the pancreas. These enzymes, pancreatic amylase, trypsin, chymotrypsin and lipase do not interact with the chyme until it enters the small intestine. Chyme is then further degraded into small molecular chains that can be assimilated at the cellular level.

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