What is GERD (acid reflux)?
Gastroesophageal reflux disease, commonly referred to as
GERD, or acid reflux, is a condition in which the liquid
content of the stomach regurgitates (backs up, or refluxes)
into the esophagus. The liquid can inflame and damage the
lining of the esophagus although this occurs in a minority
of patients. The regurgitated liquid usually contains acid
and pepsin that are produced by the stomach. (Pepsin is an
enzyme that begins the digestion of proteins in the
stomach.) The refluxed liquid also may contain bile that has
backed-up into the stomach from the duodenum. (The duodenum
is the first part of the small intestine that attaches to
the stomach.) Acid is believed to be the most injurious
component of the refluxed liquid. Pepsin and bile also may
injure the esophagus, but their role in the production of
esophageal inflammation and damage (esophagitis) is not as
clear as the role of acid.
GERD is a chronic condition. Once it begins, it usually is
life-long. If there is injury to the lining of the esophagus
(esophagitis), this also is a chronic condition. Moreover,
after the esophagus has healed with treatment and treatment
is stopped, the injury will return in most patients within a
few months. Once treatment for GERD is begun, therefore, it
usually will need to be continued indefinitely.
Actually, the reflux of the stomach's liquid contents into
the esophagus occurs in most normal individuals. In fact,
one study found that reflux occurs as frequently in normal
individuals as in patients with GERD. In patients with GERD,
however, the refluxed liquid contains acid more often, and
the acid remains in the esophagus longer.
As is often the case, the body has ways (mechanisms) to
protect itself from the harmful effects of reflux and acid.
For example, most reflux occurs during the day when
individuals are upright. In the upright position, the
refluxed liquid is more likely to flow back down into the
stomach due to the effect of gravity. In addition, while
individuals are awake, they repeatedly swallow, whether or
not there is reflux. Each swallow carries any refluxed
liquid back into the stomach. Finally, the salivary glands
in the mouth produce saliva, which contains bicarbonate.
With each swallow, bicarbonate-containing saliva travels
down the esophagus. The bicarbonate neutralizes the small
amount of acid that remains in the esophagus after gravity
and swallowing have removed most of the liquid.
Gravity, swallowing, and saliva are important protective
mechanisms for the esophagus, but they are effective only
when individuals are in the upright position. At night while
sleeping, gravity is not in effect, swallowing stops, and
the secretion of saliva is reduced. Therefore, reflux that
occurs at night is more likely to result in acid remaining
in the esophagus longer and causing greater damage to the
esophagus.
Certain conditions make a person susceptible to GERD. For
example, GERD can be a serious problem during pregnancy. The
elevated hormone levels of pregnancy probably cause reflux
by lowering the pressure in the lower esophageal sphincter
(see below). At the same time, the growing fetus increases
the pressure in the abdomen. Both of these effects would be
expected to increase reflux. Also, patients with diseases
that weaken the esophageal muscles (see below), such as
scleroderma or mixed connective tissue diseases, are more
prone to develop GERD.
Article from:
http://www.medicinenet.com/gastroesophageal_reflux_disease_gerd/article.htm
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