The loop of Henlé and the medullary salt gradient

Overview

Overall purpose of the loop of Henlé and salt gradient that exists in the medulla.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is the overall purpose of the loop of Henlé?

   Model answer

   The loop of Henlé creates a salt gradient in the medulla that allows water to be recovered osmotically from the filtrate.

2. 2

   What happens to the filtrate as it moves down the descending limb?

   Model answer

   Water leaves the descending limb into the surrounding medulla, so the filtrate becomes progressively more concentrated.

3. 3

   At which point in the loop is the filtrate most concentrated?

   Model answer

   The filtrate is most concentrated at the apex, the hairpin bend at the bottom of the loop.

4. 4

   Which two ions leave the ascending limb of the loop of Henlé?

   Model answer

   Sodium ions and chloride ions leave the ascending limb of the loop of Henlé.

5. 5

   Where do the ions that leave the ascending limb go?

   Model answer

   They pass out into the tissue fluid of the surrounding medulla.

6. 6

   Why does water not follow the ions out of the ascending limb?

   Model answer

   The ascending limb is impermeable to water, so ions can be moved out of it without water leaving with them.

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