Lower Esophageal Sphincter

A properly functioning cardiac sphincter prevents stomach contents from rising. Restoring stomach acid to the correct pH allows the esophageal sphincter to regain proper tone and prevent reflux. The autonomic nervous system directly controls the lower esophageal valve, and nerve dysfunction causes the valve to lose tone. The lower esophageal valve prevents stomach acid from reaching the esophagus, and its failure to close completely causes reflux. Three distinct mechanisms govern whether the lower esophageal valve closes correctly. The cardiac sphincter is designed to function as a one-way valve. The cardiac sphincter controls the passage between the stomach and the esophagus. A weakened cardiac sphincter allows stomach acid to escape into the esophagus. When stomach acid is at the correct pH, the lower esophageal sphincter maintains proper tone and stays tightly closed. The valve closes in response to sufficient gastric acidity; when stomach acid is too weak, the valve fails to close and allows acid to escape upward. The article states that the cardiac sphincter is closed when relaxed and opens when tightened. Nightly gravitational load gradually reduces the sphincter's ability t…