text: what is the purpose of the gastroesophageal sphincter? need to know asap when we eat and swallow our chewed food, that food moves down our esophagus through rhythmic contractions of muscle tissue. the esophageal sphincter is a ring-structured muscle that effectively acts as a door to food going from theesophagus into the stomach. it normally stays closed but opens only when letting food into the stomach from the esophagus. some people have a condition called gerd in which the contents of the stomach- which are very acidic- reflux (flow back into) the esophagus, irritating it, this condition is believed to be caused by a malfunctioning esophageal sphincter that sometimes stays open by accident.