Long loop of Henle in juxta medullary nephron helps in the

Long loop of Henle in juxta medullary nephron helps in the increase in the concentration of urine.

Juxtamedullary nephrons have a longer loop of Henle that extends deep into the medulla of the kidney. This extended loop allows for a greater osmotic gradient to be established along the medullary interstitium, from the cortex to the deep medulla. As filtrate flows through the long descending and ascending limbs of the loop of Henle, water is reabsorbed from the filtrate in the descending limb due to the high osmotic concentration of the surrounding interstitium.

In the ascending limb, sodium (Na⁺), chloride (Cl^-), and other ions are actively transported out of the tubule, creating a dilute filtrate. The concentrated interstitium, in turn, draws out water from the descending limb of the loop of Henle. This countercurrent multiplier mechanism, facilitated by the long loop of Henle and the associated vasa recta, sets up concentration gradient that enables the kidney to produce concentrated urine and conserve water effectively.