1. What is gastroesophageal reflux disease? GERD is the reflux of gastroduodenal contents into the esophagus causing heartburn, acid reflux and other symptoms and can lead to esophagitis and damage to tissues outside the esophagus such as the pharynx, larynx and airway. 2.Why gastroesophageal reflux does not occur in normal people? (a) At the lower end of the esophagus immediately adjacent to the gastric cardia, there is a slightly thickened circular muscle, about 2 to 4 cm long, called the lower esophageal sphincter (LES), which plays an important role in preventing reflux. This sphincter is tense and contracted to prevent reflux from occurring. Under normal conditions, the LES must have a normal length, a pressure, and a transient relaxation. Auxiliary primary use of the diaphragm and diaphragm foot. (b) Under normal conditions, the esophagus empties rapidly, and even if there is regurgitation of gastric and duodenal fluids into the esophagus, it immediately stimulates the esophagus to strengthen the peristalsis Esophageal peristalsis, mechanically clears acid, and empties the regurgitant downward. In addition, the saliva in the mouth is swallowed into the esophagus, which dilutes, neutralizes and flushes the reflux, reducing the erosive effect of the reflux on the esophageal mucosa. (C) The normal barrier function of esophageal mucosa, to a certain extent, can resist the damage of Esophageal tissue resistance to the esophageal mucosa by reflux. (D) The timely gastric emptying function Proper stomach emptying 3, why do some people have gastroesophageal reflux disease? (1) Frequent transient relaxation of the lower esophageal sphincter dysfunction (LES dysfunction, TLESR), which weakens the anti-reflux mechanism. (2) Defective esophageal clearance: Decreased salivation, Esophagea dysmotility, and decreased ability of the esophagus to clear reflux and dilute acid. The mechanical defense mechanism is weakened. 3) Hiatal Hernia, an esophageal hiatus hernia, due to pathological changes in anatomical location, makes the original structural basis of the organ resistant to reflux weaken or disappear. 4) The action of some corrosive substances in the stomach Caustic Agents: for example, gastric acid Acid, pepsin Pepsin, etc.. Excessive secretion makes the aggressive factors enhanced and prone to cause damage to the mucosa. 5) Delayd gastric emptying. can make the pressure in the stomach increase and intensify the reflux symptoms.