What is GERD?
The esophagus carries food and liquid into the stomach. At the lower end of the esophagus where it enters the stomach, there is a strong muscular ring called the lower esophageal sphincter (LES). The LES should remain tightly closed, except to allow food and liquid to pass into the stomach.
Reflux occurs when the LES is not working properly. It may relax for periods of time throughout the day and night, or it may be constantly too weak to function effectively. This allows the stomach’s acid juices to flow into the esophagus. How severe the disease becomes depends on how weakened the LES is, and the amount and duration of acid refluxed into the esophagus.
It is also common to find a hiatal hernia complicating GERD. With a hiatal hernia, the upper part of the stomach actually pushes up into the chest through a weakness in the diaphragm. The diaphragm is the thin, flat muscle that separates the lungs from the abdomen. When part of the upper stomach is stuck above the diaphragm, stomach acid is retained there for a longer period and is more likely to reflux into the esophagus.