Water Balance Flashcards
What stimulates secretion of ADH?
increase in plasma osmolality
decrease in blood volume
“Other” things that can control ADH concentrations
pain, nausea, medications, narcotics, pregancy
Nephron type that controls H2O balance
juxtacorticomedullary nephrons
they dive deep into medullary space
What creates osmolarity gradient in absence of ADH?
NKCC pump in ascending tubule
NKCC pump can create gradient in interstitium up to
600 mOsm
How does ADH increase H2O reabsorption?
increases osmolarity gradient in interstitium to 1200 mOsm
increases aquaporin presence in collecting duct
How does ADH increase osmolarity gradient in interstitium?
moves urea into interstitium via UT-1 transporter in the collecting duct
Juxtacorticomedullary nephrons do not have the traditional peritubular capillary network
they DO have…
vasa recta
Vasa recta
vs
Peritubular capillary network
vasa recta run perpendicular to tubules
not interweaved around tubules like the peritubular capillary network
Vasa recta are branches off of…
efferent arteriole
(just like pericapillary network)
Subtypes of urea transporters
UT-1:
transports urea from collecting tubule into interstitium
only means of getting urea into insterstitium
UT-2:
transports urea from interstitium back into ascending tubule
only 50% reabsorbed typically
ADH receptor
for aquaporin release
V2 receptor
V2 receptor
ADH receptor
activates adenylate cyclase
ATP → cAMP
CREB phosphorylation
CREB → CREB-P
AQP-2
aquaporin on lumenal surface
AQP-3,4
aquaporins on abluminal/basolateral/interstitial surface of collecting duct tubule
