Kidney reabsorption

[livinitup]

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Can someone clarify my understanding of ADH and Aldosterone? I think I finally understand it but I'm not sure.

They both work to increase permeability of the collecting duct to increase water reabsorption.

Aldosterone directly causes sodium reabsorption of the collecting duct and water follows, while ADH increases permeability of water due to the increasing osmolarity of the interstitium.

Is this right?

 

[echoyjeff222]

Aldosterone and ADH exert their effects at the distal nephron. Aldosterone causes active Na transport into the blood, while ADH causes increased water permeability (I always thought that meant like more porous or something, not sure ...) the overall effect is to suck out water from the urine, though, and increase blood volume.

 

[livinitup]

Thanks!!! 🙂

 

[livinitup]

So if Aldosterone causes active Na reabsorption into the blood, whats going on with the nephron? Is it now isotonic to the blood?

 

[echoyjeff222]

If I recall, the urine gets more hypotonic as you ascend the loop of henle. At the distal tubule you get more absorption, but I don't think you get more concentrated again until sometime in the collecting duct (since it's salty in the medulla there and stuff diffuses in the urine)