Question

G.F at the base of Henle’s loop is

A. Isotonic

B. Hypotonic

C. Hypertonic

D. Insoluble

Answer 1

Hint: Henle 's loop is a  long U-shaped loop of the tubule that conducts urine in reptiles, birds and mammals inside each nephron of the kidney.

Complete Answer:

- The key feature of Henle 's loop is to reabsorb sodium and other solutes from the glomerular filtrate. This function enables urine output that is much more concentrated than blood, reducing the amount of water required as a survival intake.

- Henle's loops are highly effective in many animals that live in arid environments such as deserts. The Henle loop can be split into two main segments anatomically: descending limb and ascending limb.

- The liquid entering Henle's loop is the solution passed by the proximal convoluted tubule of salt, urea, and other substances from which most of the dissolved components required by the body have been reabsorbed into the blood, especially glucose, amino acids, and sodium bicarbonate.

- The loop's first part, the thin descending limb, is permeable to water, and the liquid approaching the loop's bend is much richer in salt and urea than the plasma of the blood. Sodium chloride diffuses out of the tubule into the surrounding tissue, where its concentration is lower, as the liquid returns through the thin ascending limb.

- Isotonic (300 mOsm / L) fluid from the proximal convoluted tubule (PCT) is obtained by the descending loop of Henle. 

- The fluid is isotonic since water is often reabsorbed as ions are reabsorbed by the gradient time mechanism, preserving the osmolarity of the fluid in the PCT. Urea, water, potassium , sodium, chloride, glucose, amino acids, lactate, phosphate, and bicarbonate are the substances reabsorbed in the PCT.

- The increased concentration of solutes in the interstitial fluid results in the entry of water from the vasa recta. The entry of water will change the isotonic glomerular filtrate to hypertonic and the urine becomes approximately 4 times more concentrated than the human blood plasma i.e., from 300 milliosmoles to 1200 milliosmoles.

The correct answer is option (C) Hypertonic.

Note: The reabsorption of salt from the urine in a healthy person specifically retains the body 's requirement.