Upper Gastrointestinal Flashcards
How do NSAIDs lead to mucosal damage?
increased neutrophil adherence
damage from neutrophil derived free radicals & proteases
What do G cells secrete?
gastrin
What does gastrin stimulate? How?
enterochromaffin-like cells
action at gastrin/cholecystokinin2 receptors
What receptor is found on parietal cells?
gastrin receptors
What do enterochromaffin-like cells release? What is this enhanced by?
histamine
enhanced by gastrin and acetylcholine
What does Somatostatin inhibit?
release of gastrin
histamine
acid from parietal cells
How do Prostaglandins protect gastric mucosa?
increasing bicarbonate secretion
increase protective mucus production
reduce gastric acid secretion
Tests to detect presence of Helicobacter pylori
carbon-13 urea breath test
stool antigen test
lab-based serology test
How to treat functional dyspepsia if H.pylori is not present
4 week-course of proton pump inhibitor
or H2 blocker
H.pylori mechanism of action
produces urease, releases ammonium chloride
increase pH stimulates G cells
inflammatory mediators inhibit D cells
G cells increase release of gastrin
increased acid secretion, increased risk of ulcer formation
What do D cells release?
Somatostatin
First line treatment for H.pylori
7 day, twice daily
PPI
amoxicillin, clarithromycin/metronidazole
Second line treatment for H.pylori
out of clarithromycin/metronidazole
whichever wasn’t used first
Treatment for gastro-oesophageal reflux disease
full dose of PPI for 4 or 8 weeks
Treatment for GORD, if inadequate response to PPI?
offer H2 receptor Antagonist
Treatment for GORD, if oesophageal stricture present?
long-term, full-dose PPI treatment
Examples of Proton-pump inhibitors
omeprazole
lansoprazole
Where do Proton-Pump Inhibitors concentrate?
canaliculi of parietal cells
What do Proton-Pump Inhibitors target?
H+/K+ ATPase pump
The active form of omeprazole
sulfanemide form
Suffix of PPIs
’‘-prazole’’
Clinical uses of PPIs (5)
gastric and duodenal ulcer hypersecretory states GORD NSAID associated ulcer dyspepsia relief
H2 receptor analogue examples
Ranitidine
Famotidine
Cimetidine
H2 receptor analogue suffix
’‘-tidine’’
H2 receptor analogue mechanism of action
competitive antagonists
reduced action of histamine in acid production
Antacid examples
Sodium bicarbonate salts
Magnesium hydroxide
Magnesium carbonate
Aluminium hydroxide gel
Antacid mechanism of action
weak bases
quickly neutralise hyperacidity of stomach
in dyspepsia
short term
Bismuth Salts mechanism of action
toxic to H.pylori
interfere with adherence to gastric mucosa
treatment of mild dyspepsia
What is Sucralfate made up of?
aluminium hydroxide
sulfated sucrose
Sucralfate mechanism of action
provides protective coating on the mucus
