The gastrointestinal, or GI, tract includes the oral cavity, pharynx, esophagus, stomach, and the small and large intestine. The GI tract is part of the digestive system, and it is responsible for moving food and liquid into and out of the body.

At the junction of the esophagus and the stomach lies a muscle called the lower esophageal sphincter, which opens to allow food to enter the stomach and then closes to keep food and stomach acids from flowing back into the esophagus. If there is too much pressure in the stomach, or if the sphincter muscle is not functioning properly, then contents of the stomach can splash back into the esophagus, causing symptoms of gastroesophageal reflux disease, or GERD. These symptoms may include heartburn, chest pain, coughing or choking while lying down, or increased asthma symptoms while sleeping.

Diet and lifestyle changes can relieve some of the symptoms associated with GERD; however, in some cases medication or surgery are necessary.