Question

Fluid within the loop of Henle is concentrated in the

• A. Descending limb
• B. Thick ascending duct
• C. Hairpin bend between descending and ascending limbs
• D. Bend between the ascending limb and the distal tubule

Answer 1

Answer: (C)

Hairpin bend between descending and ascending limbs

In Henle's loop, the reabsorption is minimum. However, this region plays a significant role in the maintenance of high osmolarity of medullary interstitial fluid. The descending limb of the loop of Henle is permeable to water but almost impermeable to electrolytes. This concentrates the filtrate as it moves down. The ascending limb is impermeable to water but allows transport of electrolytes actively or passively. Therefore, as the concentrated filtrate pass upward, it gets diluted due to the passage of electrolytes to the medullary fluid. Thus, the filtrate is maximum concentrated in the hairpin bend between descending and ascending limbs of the loop of Henle.