The concentration of sodium and chloride ions is lowest in which of the following regions?

$A$: The final reabsorption of water from urine into blood occurs through the collecting duct of a mammalian nephron,resulting in the production of hyperosmotic urine.
$R$: The loop of Henle is responsible for the formation of a sodium gradient across the depth of the medullary interstitium of a mammalian kidney.

Which part of the nephron plays a significant role in the maintenance of high osmolarity of the interstitial fluid?

Medullary gradient is mainly developed due to

If Henle's loop were absent from mammalian nephron,which of the following is to be expected?

The concentration of urine depends upon which part of the nephron?