How does a healthy digestive system work?

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Lawrence S. Friedman, MD
Gastroenterology
The "gut." It's an ancient Anglo-Saxon word that refers to the human digestive system. Think of this marvel of nature's engineering as a perpetual food processor, constantly mixing, grinding, and transforming the meats, vegetables, fruits, and snacks that people eat into biologically useful molecules.

Nearly 30 feet long if stretched out straight, the gut is a series of hollow organs linked to form a long, twisting tube that runs from the mouth to the anus. This string of organs is known as the alimentary canal, gastrointestinal (GI) tract, or digestive tract. It comprises the esophagus (or gullet), stomach, small intestine, and colon (which includes the rectum). These organs break down food and liquids -- carbohydrates, fats, and proteins -- into chemical components that the body can absorb as nutrients and use for energy or to build or repair cells. What's left is expelled by a highly efficient disposal system.

The organs of the gut are almost always moving, driven by muscles in their walls. These muscles consist of an outer longitudinal layer and an inner circular layer. The coordinated contractions of these layers push food and fluids the length of the canal, just as rolling waves deposit sand and shells on the shore. This dynamic movement along the gastrointestinal tract is known as peristalsis.

Helping with the job of digestion is the mucosa, or lining, of the mouth, stomach, and small intestine, which harbors glands that produce digestive enzymes. The salivary glands, liver, and pancreas also secrete juices that help make food soluble (dissolvable in water) so that nutrients can pass easily into the bloodstream.

A normal digestive system breaks down food into nutrients. Nutrients include proteins, carbohydrates, fats, vitamins, and minerals. The body needs nutrients for energy and to stay healthy.

The digestive tract runs from the mouth to the anus. When you eat food, it goes from your mouth, down your esophagus, and into your stomach. From there, it goes into your small intestine, where the nutrients are absorbed into your blood. Leftover water and solid waste then move down into your large intestine, where most of the water is absorbed back into the blood. Solid waste leaves the body out of the anus as a bowel movement.

This answer is based on source information from the National Women's Health Information Center.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.