Compare normal movement of ions and nutrients across intestinal epithelium to that of secretory diarrhea.
Water is absorbed on osmotic gradient; water follows solute. Secretory diarrhea: solute (such as Cl-) secreted into lumen--> water follows--> diarrhea
10
What are the most common causative agents of traveler's diarrhea?
Enterotoxigenic Escherichia coli (ETEC), Campylobacter jejuni, Shigella spp., Salmonella spp., other E. coli strains
10
Describe the MOA of loperamide and bismuth compounds.
Loperamide: binds peripheral mu in enteric NS--> slow colonic transit (no BBB); Bismuth: salicylate inhibits intestinal prostaglandin and Cl- secretion
10
Explain the pathophysiological effects of Enterotoxigenic Escherichia coli (ETEC) AB toxins in the stomach and intestinal tract.
increases cAMP--> upregulate CFTR and NKCCI cotransporter crypt cells--> secrete Cl- into lumen--> H2O and Na follow--> watery diarrhea
10
Describe the relationship between gut flora and IBS, including how it relates to use of probiotics.
Dysbiosis (high ratio Firmicutes :Bacteroidetes, few Lactobacilli &Bifidobacteria-> activation gut immune system-->inflammation; attempt to restore symbiosis
10
Explain how motor and sensory abnormalities can provoke symptoms of IBS.
Visceral hypersensitivity (distention); Visceral mesenteric nerves respond to distention and serotonin&bradykinin; histamine activates pain fibers
10
Describe the major motor patterns that occur in the small intestines and colon during FED and FASTED conditions.