Pathophysiology of Diarrhea Flashcards
what are the three types of diarrhea?
osmotic
malabsorption/maldigestion/fatty (steatorrhea)
secretory
explain osmotic D?
caused by excess amount of poorly absorbable, low MW substances that stay in intestinal lumen
***Na uptake maxed out, stays in lumen
water NOT absorbed
what’s a clinical correlation for osmotic D?
salt toxicity
explain malabsorption/maldigestion/fatty D
water retention in lumen
maldigest - digestion breaks down complex nutrient molecules
malabsorb - simple molecules are absorbed through apical and moveed to basolateral
what are the clinical correlations for malabsorption/maldigestion/fatty D?
exocrine pancreas insufficiency
lactose intolerance
lymphangiectasia
what is exocrine pancreas insufficiency?
inadequate production of digestive enzymes by pancreatic acinar cells
describe lactose intolerance
lactase deficiency at brush border
what is lymphangiectasia in dogs?
engorged lymphatics have narrow rim of small lymphocytes and expand villi
compromised nutrient absorb
increased venous/lymphatic P due to malformation of lymphatic drainage/tumor causing obstruction
what is secretory D?
excessive/uncontrolled ion transport
toxin affecting CFTR
list some mediators that stim Cl secretion via CFTR
bacterial toxin
FA
bile acids
what are the clinical correlations of secretory D?
cholera
E coli
oral rehydration therapy
what is cholera effect on CFTR?
toxin released from bacteria
activates G protein -> activate adenyl cyclase -> increased cAMP -> opens CFTR
what is E coli effect on CFTR?
stim membrane adenyl cyclase or G protein -> increase cGMP -> open CFTR
causes electrogenic Cl secretion
why is nutrient absorption in SI largely normal in setting of secretory D?
SLUTGLUT in SI
why is secretory D unaffected by fasting?
CFTR activated by toxins/agents, even without digesta in GI
what is gastrinoma?
D as result of multiple mechanisms
what are the three metabolic syndromes that D has been linked with?
describe metabolic alkalosis and hypokalemia relation to D
GI H loss
volume contraction
decreased K intake
what does metabolic acidosis and hypokalemia lead to?
