Digestion is the process of turning food into fuel for energy, and for maintenance of the body structure. The digestive tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce enzymes to help digest food. There are also two solid digestive organs, the liver and the pancreas, which produce enzymes that reach the intestine through small tubes.

During the digestive process, food passes down the throat, through the esophagus, and into the stomach, where food continues to be broken down. The partially digested food passes into a short tube called the duodenum the first part of the small intestine. The jejunum and ileum are also part of the small intestine. The liver, the gallbladder, and the pancreas produce enzymes and substances to help with digestion in the small intestine. After the digestive process is complete, the resulting waste travels downstream to the colon. The colon and rectum are parts of the body's digestive system, which removes nutrients from food and stores waste until it passes out of the body. Together, the colon and rectum form a long, muscular tube called the large intestine.

The health of your digestive system has a lot to do with lifestyle the food you eat, the amount of exercise you get, and the pace and stress level of your day. However, some digestive diseases, such as those discussed here, are thought to be hereditary or stem from an infection. For others, there is no known cause.