Kidney filtration

[dohopeful12345]

As you descend into the inner medulla of the kidney, the osmolarity increases. So how does water get pulled from the descending loop of henle into the blood vessel? Wouldn't the medulla have higher osmolarity than the blood vessel as well?

So i imagine the water path as going:

descending loop of henle -> inner medulla -> blood vessel

But if the inner medulla have the highest osmolarity, why does it go to the blood vessel?

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[PhilzCoffeeAddict]

Tubular reabsorption article

^ This article is very useful and what I used to learn more about your question.

This question is challenging. I believe this has to do with countercurrent between the blood vessel and renal tubules. We're both on same page that the medulla gets very concentrated with salts and water follows but how it transfers that into the blood vessels is beyond my understanding.

 

[pretty_positron]

Not sure what you're asking?

The concentration of salts rises as you go deeper into the medulla of the nephron, this means that water is pulled out through diffusion (osmosis).