Urinary Concentration Mechanisms Flashcards
how does ADH signaling work?
binds to G protein coupled V2 receptor
G protein activates adenylate cyclase which makes cAMP which activates PKA
PKA phosphorylations result in aquaporin and urea transporter insertion
what is the urine concentration excretion requirement?
600mOsmoles/day
what is max antiduresis?
0.5 L of 1200mOsmole urine
what is max diuresis?
10L of 60 mOsm urine
what is the gradient between the tubule and interstitial in the loop of henle?
200 mOsm
how does the counter current multiplier system work?
water is removed from thin descending tubule and Na is removed from the thick ascending tubule to make the tubular fluid/interstitial fluid the correct concentration to maintain the 200mOsm concentration gradient
- concentration of thin descending tubule and interstitial match–>thick ascending is 200 more
- concentration of collecting duct matches the concentration of interstitial fluid
what are osmotic diuretics?
presence of poorly reabsorbed osmolytes cause tubules to retain water, which increases urine flow (glucose, mannitol, isosorbide)
what can osmotic diuretics be used for?
stalled/failing kidneys to increase urine flow
what is syndrome of inappropriate ADH release?
high ADH with inappropriate water conservation
results in hypotonic volume expansion
what are the symptoms of syndrome of inappropriate ADH release?
hyponatremia
hyposmotic plasma
hyperosmotic urine
increased Na excretion
how is inappropriate ADH release treated?
fluid restriction
hypertonic NaCl administration
ADH antagonists
what is diabetes insipidus?
lack of ADH control resulting in uncontrolled water loss
hypertonic volume contraction
what are symptoms of diabetes insipidus?
polydipsia
polyuria
elevated plasma Na and osmolality
what is central diabetes insipidus?
central defect in ADH defect
what is nephrogenic diabetes insipidus?
renal defect in responding correctly to ADH
