Overview of the Digestive Tract (Also Called the Gastrointestinal Tract)

A wide array of disorders can affect your digestive tract, a long tube of organs that begins at your mouth and ends at your anus. Some disorders, such as an occasional bout of heartburn, are minor annoyances. But many digestive disorders, such as Crohn's disease or irritable bowel syndrome, can severely affect your ability to do your daily activities, and some, like colorectal cancer or a perforated ulcer, can be life threatening.

There are many conditions that affect the digestive tract, including diseases of the:

  • esophagus
  • stomach
  • liver
  • gallbladder
  • bile ducts
  • pancreas
  • small intestine
  • large intestine
  • rectum
  • anus

Over 70 million Americans have digestive disorders, which prompt nearly 60 million visits to doctors' offices and hospitals each year. Doctors who treat digestive disorders are called gastroenterologists.

Although digestive disorders can affect people of any age, many of these problems occur more frequently as we get older. Digestive disorders have many possible causes, most commonly infections and dietary factors. Some people have a genetic predisposition that makes them susceptible to these and other environmental triggers. But the causes of some digestive disorders are still unknown.

Although many of the symptoms of digestive disorders—gas, diarrhea, constipation, and blood in the stool—can be embarrassing to discuss, it's important to contact your doctor if you develop any of them. These symptoms can be a sign of something wrong with your digestive tract, and detecting the problem early will improve the chances of successful treatment. Fortunately, treatment options ranging from lifestyle measures to medications and surgery can alleviate the symptoms, often completely.

The Digestive Tract

Digestive Tract Image - Masterfile

The digestive tract consists of a series of hollow and solid organs and glands that span the length of the body from your mouth to your anus and secrete digestive juices. The major organs along the tract are the esophagus, stomach, small intestine, large intestine (colon), and rectum.

The role of the digestive tract is to break down food and fluids to provide the body with the energy it needs to function properly as well as the substances required to build and nourish cells. Through a process called peristalsis, rhythmic muscle contractions push the food through the length of the digestive tract. Nutrients from food are absorbed in the small intestine, and what remains undigested passes into the colon and ends up in the stool.

The digestive system breaks down food into absorbable units that enter the bloodstream to nourish cells. Food is crushed, mixed, and pushed forward by the wavelike contractions of the esophagus, stomach, and intestine. Food is also broken down by digestive enzymes secreted by the salivary glands, stomach lining, intestine, and pancreas.

Digested nutrients are absorbed through the small intestine's walls; waste products are propelled into the large intestine and eliminated as stool (feces). Nearly all digestion occurs in the small intestine, which has three parts: the duodenum, jejunum, and ileum. In the duodenum, pancreatic enzymes and bile from the liver and gallbladder break down food into absorbable units.

Almost all nutrients are absorbed through the walls of the jejunum and ileum; the residue passes into the large intestine (colon). Here, excess water and electrolytes are absorbed from the waste, which is broken down further by intestinal bacteria and stored until excreted. The large intestine consists of the cecum, colon, rectum, and anal canal.

Publication Review By: H. Franklin Herlong, M.D.

Published: 22 Mar 2011

Last Modified: 11 Sep 2015