Flashcards in GI Deck (49)
What are the four sets of GI drugs?
1. Acidity, ulcers GERD
2. Bowel motility, water flux
3.Reduce prevent nausea
What stomach cells secret HCl?
What increases acidity production in the stomach 3 Receptors?
What happens to HCO3 from its dissociation from H+ in the stomach epithelial?
exported into blood in exchange for Cl-
What nerve begins cephalic response? acts on what cells?
vagus- M receptors of parietal cell and ECL cells (Fundus) which release histamine in a long term manner
Where is G cell located? What cells does gastrin work on?
antrum, Parietal and ECL cells
What stims Gastrin release?
Increase pH and stretch
How does PGE2 and PGI2 promote protection from gastric acidity?
activate Gi and decrease cAMP to decrease acid
**also same receptor in epithelial cell causes increased mucus and bicarb secretion**
What pumps protons out of the parietal cell?
H/K ATPase. K is recycled with Cl antiporter
Does a PPI stop working after its 2 hour activity window (acid labile)? What activates them?
No because of irreversible binding
Stomach acid activates
Where does PPI reach the cell?
Through blood. It is acid labile and therefore must be protected as it passes through stomach.
What is Zollinger Ellison Syndrome?
secretion of Gastrin from tumors of pancreas and intestine.
Where are PPIs cleared? CYP influences?
Liver- increase serum warfarin, decrease activation of clopidogrel
What is useful to block for nocturnal acid secretion?
H2 receptors blockers (24 hour effectiveness 70%)
How are H2 blockers secreted?
Renal- organic cation system
How long does it take tolerance to develop with H2 blockers?
3 days--> increased Gastrin
Does sucralfate stick better to gastric or duodenal ulcers? how is it activated?
duodenal, acid activated
Is Mg or Al fast acting as an antacids? What is added to reduce case?
1. Mg (stimulates gastric emptying and motility while Al slows)
2. Surfactant simethicone
Where does muscaranic antagonists work?
M1 intramural ganglia!!!!!!
What determines if the H. pylori infection will be pathogenic?
Vacuolating endotoxin A
What are the 3 types of therapy for H Pylori?
Quadruple- PPI+metro+ bismuth+ tetra
Quadruple- H2 blocker+bismuth+metro+tetra
mechanical stim of Enterochromaffin cells release what?
serotonin--> primary afferent-->reflex contracts orally and relax anally
Does dopamine generally decrease or increase ACh release?
What cells secrete motilin?
enterochromaffic cells and M cells in upper small bowel
What are 60% of constipated patients actually complaining about? How to treat?
stool hardness (normal transit times)
T-F--laxatives are really cathartics at lower dosages but act as laxatives when the dose is increased
False- opposite is true- cathartic means to purge
What type of drugs are best for constipation with associated opioid use?
Do stool wetting agents increase frequency of defecation?
No-- just soften the stool
Does castor oil actually stimulate smooth muscle? Is the castor bean toxic?
Yes, yes due to soluble Ricin fraction