Gastroesophageal reflux, often referred to as GERD, occurs when acid from
the stomach backs up into the esophagus. Normally, cooking.net">food travels from the
mouth, down through the esophagus and into the stomach. A ring of muscle at
the bottom of the esophagus, the lower esophageal sphincter (LES), contracts
to keep the acidic contents of the stomach from "refluxing" or coming back
up into the esophagus. In those who have GERD, the LES does not close
properly, allowing acid to move up the esophagus.

For further information pls check it out:
http://www.***.com/