Digestion is the process by which food and liquid are broken down into smaller parts so that the body can use them to build and nourish cells, and to provide energy. Digestion begins in the mouth, where food and liquids are taken in, and is completed in the small intestine.

Digestion involves the mixing of food, the movement of food through the digestive tract, and the chemical breakdown of large molecules of food into smaller molecules.

In a wave-like movement, called peristalsis, muscles propel food and liquid along the digestive tract. The involvement of the upper GI tract includes the following:

• The first major muscle movement is swallowing food or liquid. The start of swallowing is voluntary, but once it begins, the process becomes involuntary and continues under the control of the nerves.
• The esophagus, which connects the throat above with the stomach below, is the first organ into which the swallowed food goes.
• Where the esophagus and stomach join, there is a ring-like valve that closes the passage between the two organs. As food nears the valve, the surrounding muscles relax and allow food to pass into the stomach. The valve then closes.
• The food then enters the stomach, which completes three mechanical tasks of storing and mixing the food, then emptying it into the small intestine.
• The food is digested in the small intestine and dissolved by the juices from the pancreas, liver, and intestine and the contents of the intestine are mixed and pushed forward to allow further digestion.

Upper G.I. procedures help physicians diagnose and treat problems in the liver, bile ducts, pancreas and esophagus.

Conditions for when an Upper G.I. Procedure May be needed:

Barrett's Esophagus
Heartburn and Reflux
Gastroesophageal Reflux Disease (GERD)/Heartburn
Helicobacter Pylori
Hiatal Hernia
Peptic Ulcer Disease

Source:  www.placentialinda.staywellsolutionsonline.com/library/encyclopedia and American Society of Gastrointestinal Endoscopy http://www.asge.org/PatientInfoIndex.aspx?id=378