Water Balance Control Flashcards
How is medullary interstitial hyperosmolarity generated?
Active NaCl transport by TALH
How is the medullary interstitial hyperosmolarity maintaned?
Differential NaCl and water permeabilities within the segments of the loop of Henle
What molecules contribute to hyperosmolarity?
Urea and NaCl
What is ADH effect on urea?
It increases the permeability / recylcing of it
What is ADH effect on urea?
It increases the permeability / recycling of it
What is pitressin?
Synthetic ADH
What is the vertical osmotic gradient in the kidney?
As you move inward from the cortex to the papillary osmolarity increases
What allows for greater hyperosmolarity in the medulla?
The length of the loops of nephrons allows for more water conservation and hyperosmolarty
What is countercurrent exchange?
The hairpin loop allows for equilibration with interstitial osmolarity by exchanging H2O and NaCl
Where is urea transport?
- PT (paracellular)
- ascending thin limb (take urea in)
- IMCD (affected by ADH)
Describe urea’s journey through kidney.
Low concentrations in the DTL start to increase as water leaves the DTL. More urea is added from the IMCD into the ATL. This increases the concentration. In the DCT the concentrations increase more as NaCl leaves. Urea then to in the IMCD to go back into the ATL and is affected by ADH
Changes in osmolarity trumps what?
Changes in volume
What is the overall effect of ADH on renal concentration mechanism?
Overall positive effect
Why isnt concentration of Na a good measurement of ECF?
Excretion of Na is not governed by the concentration but the total amount. It is balanced by dietary intake and urinary output
