Gastroesophageal Reflux Disease (GERD)
The terminal end of the esophagus possesses a lower esophageal sphincter (specialized smooth muscle that is pharmacologically different from the smooth muscle lining the lower esophagus). It prevents the reflux of gastric contents into the lower esophagus. However, it can become compromised, usually by a loss of muscle tone or a sliding hiatal hernia, leading to GERD and inflammation of the esophageal lining. GERD often presents with upper abdominal pain, dyspepsia, gas, heartburn, dysphagia, bronchospasm (15% to 20%), or asthma (15% to 20%).