Read the following statements.

I) The proximity between the Henle’s loop and vasa recta, as well as the counter current in them help in maintaining an increasing osmolarity towards the inner medullary interstitium.

II) Osmolarity in cortex is 300 mOsmol L^-1and osmolarity in medulla is 1200 mOsmol L^-1.

Select the correct option.

The proximity of Henle's loop and vasa recta, along with their countercurrent flow, contributes to the establishment of an ascending osmolarity gradient in the inner medullary interstitium. This gradient allows for the effective concentration of urine. Specifically, in the cortex, the osmolarity is around 300 mOsmol/L, while in the medulla, it reaches 1200 mOsmol/L.

Henle's loop, consisting of descending and ascending limbs, plays a crucial role in generating this gradient. As the filtrate moves through the descending limb, water is reabsorbed, increasing its osmolarity. In the ascending limb, sodium and chloride ions are actively transported out, reducing the osmolarity of the filtrate.

The vasa recta, specialised capillaries around the loop of Henle, enable the countercurrent exchange of substances. As blood flows in the opposite direction of the filtrate, it absorbs water and solutes from the medullary interstitium, helping to maintain the osmotic gradient without disrupting it.

This coordinated system creates a concentration gradient in the medulla, essential for the kidney's ability to concentrate urine. It allows the collecting duct to selectively reabsorb water as needed, resulting in the production of concentrated urine and water conservation.