Structural Causes

Heartburn and acid reflux, also known as gastroesophageal reflux disease (GERD), occur when the lower esophageal sphincter (LES) muscle, located at the bottom of your esophagus, weakens or relaxes abnormally allowing acid to flow back into your esophagus. While certain foods, medications, smoking and other factors can cause this to occur, the structure of your LES, stomach and esophagus can also trigger heartburn and acid reflux.

Lower Esophageal Sphincter
One of the structural causes of heartburn and acid reflux/GERD is the malfunction of your lower esophageal sphincter (LES). This band of muscle is located at the junction between the esophagus and the stomach. The LES opens to allow food and liquid into the stomach, and then closes to keep acid and food particles from flowing back into the esophagus. If it is weak or loses tone, the LES will not close completely after food passes into the stomach. Stomach acid can then back up into the esophagus. Certain foods and beverages, drugs and nervous system factors can weaken the LES and impair its function

Stomach
Some people who have GERD have abnormal nerve or muscle function in the stomach. These abnormalities prevent the stomach muscles from contracting normally, which causes delays in stomach emptying. This can increase the risk for acid back-up.

Esophagus
Some studies suggest that most people with atypical GERD symptoms, such as hoarseness, chronic cough, or the feeling of having a lump in the throat, may have specific abnormalities in the esophagus.

• Motility Abnormalities: Problems in spontaneous muscle action (peristalsis) in the esophagus commonly occur in GERD, although it is not clear whether such problems cause the condition or are the result of long-term GERD.
• Eosinophilic Esophagitis: People with this condition may have many rings on the esophagus and persistent trouble swallowing including getting food stuck in the esophagus.  In adults, this condition occurs more frequently in men.