We return to our north to south tour of the digestive system. Next stop after the mouth is the esophagus. Actually the esophagus is more like a transit point. We do not want anything to stop there! The esophagus is the passageway from the mouth to the stomach.
It has upper and lower valves. The upper valve insures that food goes into the esophagus and not the trachea (which is used for moving the air we breathe into our lungs). The lower esophageal valve prevents food from coming back up. This valve can become incompetent and not stay completely shut. When this occurs you may experience “acid reflux” – the “back up” of “stomach acid.”
Several factors contribute to the lower esophageal valve becoming incompetent including a nervous system reaction, hormonal control, and pressure from the stomach. Eating too much food (filling the stomach beyond a reasonable capacity) can press the valve back up. The capacity of the average stomach is just one liter (approximately four cups).
Nicotine, caffeine, sugar, and alcohol have also been shown to make the lower valve incompetent. Once the valve has become incompetent you become more susceptible to experiencing acid reflux on a regular basis. We will discuss acid reflux in much more detail later.