The main function of the loop of Henle is

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:

What is the counter current mechanism?

Compare the statements $A$ and $B$.
$\text{Statement } A$: When the urine moves through the descending limb,it becomes hypertonic,and as it passes through the ascending limb of Henle's loop,it becomes hypotonic.
$\text{Statement } B$: The descending limb is permeable to sodium ions,while the ascending limb is impermeable to sodium ions.

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

Henle's loop of nephron plays a significant role in maintaining a high osmolarity in