Final answer:
When the lower esophageal sphincter fails to close properly, it allows stomach acid to flow back into the esophagus, causing acid reflux or heartburn, which can lead to GERD if it happens often.
Step-by-step explanation:
When the lower esophageal sphincter (LES) malfunctions, it fails to close properly after food passes into the stomach. This can allow the acidic contents of the stomach to flow back into the esophagus, causing a burning sensation known as acid reflux or heartburn. If this occurs frequently, it can lead to gastroesophageal reflux disease (GERD), a chronic condition where the esophageal lining is damaged by stomach acids. The LES is a ring of muscle that acts as a valve between the esophagus and stomach. It normally opens to let food pass into the stomach and closes to prevent the backflow of gastric contents.
When this sphincter malfunctions and fails to remain completely closed, it can lead to heartburn and gastroesophageal reflux disease (GERD). The acidic digestive juices from the stomach can escape into the esophagus, causing discomfort and potential damage to the esophageal lining.