From the mouth to the anus, a long and hollow passage exists in your body that measures about 29-30 feet in length in a full-grown adult. Using a complex system of digestive organs, this gastrointestinal tract passes food and drink through your system, breaking it down with juices and enzymes, extracting nutrients into the bloodstream, storing energy for later use, and removing waste.
Other than the occasional growl you might hear in a quiet room, all of these tasks are performed without you even being aware of it. But when something goes wrong, your digestive tract can severely lower your quality of life.
The digestive organs that form this hollow tract are, in order:
- stomach (and duodenum)
- small intestine (or small bowel)
- colon (or large intestine/bowel) and rectum
The solid organs in your body that aid in digestion, and maintain the proper amount of useful energy in the body, are:
Three different salivary glands in your mouth mix enzymes with the food to create a bolus, or mass, that can be easily swallowed into the esophagus. The esophagus consists of a long tube of muscles that constrict and contract in a rhythm that moves the bolus to a tight closure at its base known as a sphincter. The sphincter then relaxes and allows the bolus to pass into the stomach.
The stomach is lined with a special membrane that secretes digestive juices that begin the process of breaking down food into usable energy. These digestive juices are acidic; they literally dissolve the food you eat. However, the lining of the stomach not only creates the juices; it creates a chemical barrier that enables the organ to withstand its own digestive juices. The stomach is enclosed by two sets of sphincter muscles that keep the contents of the stomach away from the rest of the organs until this process is complete.
The small intestine
Once food as been broken down and disolved enough in the stomach, it makes its way into the first part of the small intestine which is called the duodenum. The duodenum is where food is further digested by pancreatic enzymes and bile. Next, circular folds in the small intestine help to slow the movement of food so nutrients can be absorbed into the body. Examined under a microscope, the small intestine has tiny structures known as villi that perform this absorption function. Both the folds and villi of the small intestine give this organ a large surface area, which is helpful for absorbing nutrients.
The colon and rectum
What remains after the body has absorbed the nutrients from your meal is waste product. In the colon (large intestine), water is absorbed from the liquid material that passes from the small intestine creating feces that is stored in the rectum prior to a bowel movement. When you go to the bathroom, the rectum uses a stricture that opens to allow feces to be excreted from the body.
Organs that make enzymes and add them to the food we eat are known as solid organs. Enzymes convert dissolved food (from the stomach) into energy the body can use. These organs —liver, gallbladder, and pancreas— perform many functions that aid digestion, as well as maintain a regulated energy flow to the rest of the body. These enzymes are delivered into the duodenum via the biliary tract (or biliary tree).
With so many organs performing so many functions in your digestive system, the number of things that can go wrong is vast. However, problems can be broadly categorized:
- the movement of food through the digestive tract and through the various sphincters
- the production and delivery of juices that aid in digestion, and the absorption of nutrients from food
- inflammation and organ dysfunction
- tumors and cancerous growths
The digestion system is a wonder of chemicals, muscles and membranes all working together in a very organized fashion to help keep us alive. Feeling good is a big business, and no one feels good if their digestive system is not functioning well. There are many products and recommendations on TV and the Internet that make a lot of promises. Digestive health, which can include eating well and staying fit, is never as easy as it sounds on television. We hope the information we provide will make you more informed about this complicated subject.