Chapter 28 Flashcards
where is adh synthesized
in the hypothalamus
adh is transported to the ____ and stored there
posterior pituitary
what is the stimulus for adh
osmotic change in body fluids hemodynamic change (decrease or pressure) angiotensin II
what are the effects of adh
increased water reabsorption by kidney (direct and via the increase in Na)
concentrated urine
vasconstriction
what is the action of adh on the kidney
increase in permeability to water in the late dt and cd (primary action)
increase in permeability to urea in medullary CD
What does reabsorption mean
leaving the tubule and entering the ISF
What is the vascular receptor for adh
V1
what is the renal receptor for adh
v2
binding of adh to v2 results in
increased insertion and synthesis of aquaporins into the apcial membrane of the late dt and cd
with the removal of adh, what happens to these aquaporins
they are reinternalized into the cell thus rendering apical membrane impermeable to water
what also cause thirst
changes in plasma osmolality and blood volume or pressure
what is the level of the thirst threshold compared to adh secretion threshold
thirst threshold is higher than the threshold for adh secretion
thirst is satisfied by what
the act of drinking even before sufficient water is absorbed from the GIT to correct plasma osmolality
relief of thirst
short lived; not satisfied until the deficit is corrected
where is the thirst center
inthe hypothalamus, in same region that regulates ADH
Control of extrallular fluid sodium concentration in the absence of adh and thirst mechanisms
it is poor
sodium concentration without aldosterone feedback control
sodium concentration is maintained relatively constant over this wide range of sodium intake, with or without aldosterone feedback control because aldosterone affects Na and H2O
Why dont angiotensin II and aldosterone have a major effect on plasma sodium concentration
angiotensin II and aldosterone increase both sodium and water reabsorption by the renal tubules, leading to increases in extracellular fluid volume and sodium quantity but little change in sodium concentration
what are the 2 forms of polydypsia(?) in diabetes insipidus
Central or nephrogenic
what is cenral
inadequate manufacture or release of ADH
what is nephrogenic
insensitivity of kidney to adh
what are the clinical signs
hyposthenuria (very dilute urine)
polyuria/polydipsia (increased urination and water drinking)
water deprivation of these animals can lead to
hyperosmotic body fluids
what is the osmolarity of the ISF throughout the renal cortex
isotonic
the osmolarity of the ISF in teh renal medulla does what from its boundary witht the cortex to its junction with the renal pelvis
increases progressively
what is this gradient established by
the countercurrent multiplication in the loop of Henle
it is preserved by the ______
countercurrent exchanage in the vasa recta
