1.Esophagus: low LES, decreased amplitude of esophageal peristalsis, and decreased repair ability of esophageal epithelium. 2.Gastro-esophagus: Atrophy of gastric mucosa, decrease of gastric glands, decrease of secretion of gastric motility and gastrin, and decrease of its excitatory effect on LES, which leads to the decrease of LES pressure, but the secretion of gastric acid will not be decreased, and the incidence of GERD will be increased. The coordinated movement of the gastroduodenal junction is weakened, the gastric mucosa is easily damaged, the gastric motility is weakened, which leads to the delay of gastric emptying, and the incidence of GERD is increased.