Which ions enter the vasa recta?

$A$: 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.

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

In the nephron, the transport of substances like sodium chloride and urea is facilitated by a special arrangement called the counter-current mechanism, which comprises of:

In vertebrates,the ability to produce concentrated urine is generally associated with the ............ .

Which of the following plays a significant role in the production of concentrated urine?