There are many diseases of the upper digestive tract; some of which include hiatal hernia, gastritis, ulcers, gastro-esophageal reflux disease (GERD), Barrett’s esophagus, and mouth, esophageal, gastric and small intestinal cancers. discuss everything you need to know about the upper and lower GI tracts and the diseases associated with them. Upper GI Tract Conditions The upper GI tract is made up of the mouth, esophagus, stomach, and duodenum (the first part of the small intestine). When we eat, the food and liquid travels from our throat through our esophagus to our stomach. The valve at the base of the esophagus, known as the lower esophageal sphincter, prevents food and stomach acids from flowing back up into our esophagus. The food you ate begins to digest and turns into a liquid in your stomach. (If the sphincter suddenly fails, it can allow food to flow back upward into the esophagus. This causes acid reflux.) After that, it travels from your stomach to the duodenum, where bile and digestive enzymes – which are produced by the gallbladder (with assistance from the liver and pancreas) – further break down the liquefied food. This is how your body is able to absorb the nutrients. When there are issues with the upper GI tract, symptoms can include gas, bloating, stomach pain, and heartburn. These symptoms can be quite unpleasant, but can also be a sign of a more serious underlying condition.