Gastrointestinal Ulcers Flashcards
What roles does the gastric mucosa play in the GI tract?
protects the cells of the stomach from the acid and enzymes in the lumen of the stomach
what type of cell secretes mucosa?
mucosal epithelial cells
what cells are responsible for acid secretion?
parietal cells
what is the role of HCl in the stomach?
to kill bacteria, viruses, and other parasites
what can occur if there is an overproduction of HCl?
overwhelm the mucous layer and buffer systems, and lead to ulcers
how do antacids work?
take NaHCO3 for example, it dissociates into Na+
the bicarbonate ion is absorbed into the blood and slightly increases the pH, which elevates the pH of the stomach
what are some pros and cons to using antacids?
pro: quick, easy, and effective in the short term to reduce stomach acid the pt is currently experiencing
cons:
- alkalotic urine can increase the deposition of calcium and phosphate to form a kidney stone
- increases blood sodium, exacerbating hypertension
- acid rebound due to feedback regulation (pump more acid out in response to antacid directly increasing pH)
what are the two categories of antacids? what is the difference?
systemic - NaHCO3
non-systemic - CaCO3, Al(OH)3, Mg(OH)2
non-systemic antacids do not effect extracellular or blood pH
what is the concern regarding antacids that contain Al and Ca? how is this dealt with?
constipating effect
give with magnesium
what do anticholinergics do in the treatment of overproduction of acid?
muscarinic Ach receptors in parietal cells stimulate HCl secretion from these cells; inhibition of these receptors reduces acid secretion, but not by much
how much do anticholinergics decrease acid secretion? (in percentage)
up to 40%
what are some side effects to anticholinergics?
dry mouth
vision problems
sedation, etc.
what are cytoprotectives? give two examples
drugs which protect cells from acidic damage, either directly or through stimulation of mucus
ex: sucralfate, misoprostol
how does sucralfate work?
it is an aluminum based salt that binds to hydrogen ions to form a gooey paste, increasing pH
also binds to degenerative cells, forming a protective layer
aka artificial mucous
works for 8-12h, specifically protects damaged tissue as well as reducing acidity
how does misoprostol work?
prostaglandin analogue
stimulates production of mucosal barrier
why do NSAIDs cause stomach problems?
COX inhibition causes PGE inhibition, and PGE is critical for mucous production in the stomach
how does histamine H2 blockers work?
inhibition of H2 receptors (receptors on parietal cells that increase HCl production)
highly effective in a number of acid-related disorders
what is the benefit to using H2 blockers?
very specific to the organ, so there are no adverse effects on the mucosa