558
Chapter 15
ulcer formation, it is not necessarily the primary factor, and
many patients with ulcers have normal or even subnormal rates
of acid secretion.
Many factors, including genetic susceptibility, drugs, alco-
hol, bile salts, and an excessive secretion of acid and pepsin, may
contribute to ulcer formation. The major factor, however, is the
presence of a bacterium,
Helicobacter pylori,
that is present in
the stomachs of a majority of patients with ulcers or
gastritis
(infl ammation of the stomach walls). Suppression of these bac-
teria with antibiotics usually helps heal the damaged mucosa.
Once an ulcer has formed, the inhibition of acid secre-
tion can remove the constant irritation and allow the ulcer to
heal. Two classes of drugs are potent inhibitors of acid secre-
tion. One class of inhibitors acts by blocking a specifi c class of
histamine receptors (H
2
) found on parietal cells, which stimu-
late acid secretion. An example of an H
2
receptor antagonist
is cimetidine. The second class of drugs directly inhibits the
H
+
/K
+
-ATPase pump in parietal cells. Examples of these so-
called proton pump inhibitors are omeprazole and lansopra-
zole. Although both classes of drugs are effective in healing
Endoscope
From power
source
To video
monitor
Trachea
Diaphragm
Duodenum
Pyloric
sphincter
Endoscope
Stomach
Lower
esophageal
sphincter
Upper
esophageal
sphincter
Visible
blood
vessel
Outline of
duodenal
ulcer
Normal
duodenal
mucosa
(a)
(b)
Figure 15–34
(a) Video endoscopy of the upper GI tract: The physician passes
the endoscope through the mouth (or nose) down the esophagus,
stomach, and into the duodenum. A light source at the tip of the
endoscope illuminates the mucosa. The tip also has a miniature
video chip, which transmits images up the endoscope to a video
recorder (image shown in Figure 15–34b). Local treatments can
be applied and small tissue samples (biopsies) can be taken with the
endoscope. Earlier versions of this device used fi beroptic technology.
(b) Image of duodenal ulcer taken through an endoscope (shown in
Figure 15–34a). The entire ulcer is about 2 cm across (the width of
the image).
(b) Courtesy of Fernando Carballo, M.D.
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