The digestive system is the series of organs in the body that is responsible for digesting food and extracting nutrients necessary to sustain life. It does this by breaking down food to its basic nutrients, which include vitamins and minerals, fats, carbohydrates, proteins and water, before transporting them to the small intestine, where most of these nutrients are absorbed into the body.

Digestion takes place in the alimentary canal, a tube that runs from the mouth to the anus. The major gastrointestinal organs involved in digestion include:

• Esophagus
• Stomach
• Intestines
• Colon
• Rectum

The liver and the pancreas also contribute to digestion, although they are not part of the alimentary canal. As food moves through the alimentary canal, it is broken down into a liquid substance containing nutrients that can be absorbed by the body. Acids and enzymes produced in digestive organs help this process. The portion of the food left over that does not contain nutrients is expelled from the body as feces during a bowel movement.

It usually takes between six and eight hours after a person consumes a food before it passes through the small intestine and stomach. Elimination of food residue from the colon usually begins after 24 hours, with complete elimination taking up to several days.

The functions of the digestive system are controlled by hormones, chemical messengers that are produced and released by cells in the lining of the stomach and small intestine. Other hormones in the digestive system regulate appetite.