Question

In the ascending limb of the loop of Henle, the filtrate will always be ________.

1) in equiLiBrium with the the medullary interstitial fluid
2) of a lower osmolarity than the medullary interstitial fluid
3) a higher osmolarity than the medullary interstitial fluid
4) the same osmolarity as the filtrate in the descending limb of the loop of Henle
5) a higher osmolarity than the filtrate in the descending limb of the loop of Henle

Answer 1

In the ascending limb of the loop of Henle, the filtrate will always be of a lower osmolarity than the medullary interstitial fluid.

Step-by-step explanation:

The correct option is 2) of a lower osmolarity than the medullary interstitial fluid.

In the ascending limb of the loop of Henle, the permeability to water decreases, while the permeability to solutes like sodium and chloride ions increases. As a result, water is not reabsorbed, while sodium and chloride ions are actively transported out of the filtrate, making it less concentrated than the medullary interstitial fluid. This helps in the formation of a concentration gradient, which is essential for the reabsorption of water in the collecting duct.