The glomerular filtrate in the loop of Henle gets concentrated in the descending and then gets diluted in the ascending limbs. Explain.

Explanation

When the nephric filtrate moves downward in the descending limb, then `Na^(+)` and `Cl^(-)` passively enter into it and also loses small amount of water. Entry of electrolytes and loss of water concentrates the nephric filtrate so descending limb is also called concentrating segment.
When the nephric filtrate moves upward in ascending limb, large amount of `Na^(+)` is actively transported from nephric filtrate into interstitial fluid followed by passive transport of `CI^(-)`. Loss of electrolytes but no loss of water (as its wall is impermeable to water) dilutes the nephric filtrate so ascending limb is called diluting segment.