Digestion is the process that breaks down food we eat into forms that can be taken up the gastrointestinal tract and absorbed into the bloodstream to be used by the body. Digestion begins in the mouth. Saliva in the mouth contains enzymes, which help to break down the food, and chewing breaks food down into small pieces, exposing more food surface to digestive action. The tongue helps to move the food from the mouth to the esophagus (the tube that connects the mouth to the stomach). The food then enters the stomach, where it is broken down further by digestive acids and enzymes. A meal usually leaves the stomach within two to three hours after it has been eaten. Once it leaves the stomach, the food moves into the small intestine, where muscular contractions mix the food further. Food remains in the small intestine from three to ten hours. Most of the absorption of nutrients into the bloodstream occurs during this time. The undigested material from the small intestines moves into the large intestine, where it waits to be eliminated some 24 to 72 hours later through the rectum.

Published by Relegent, 2005