Explain the mechanism of formation of concentrated urine in mammals.
The Henle’s loop and vasa recta play an important role in the formation of concentrated urine. The transport of sodium chloride in the ascending limb of Henle’s loop
results in an osmolar gradient. The creation of a hypertonic medulla is facilitated by the renal tubules and vasa recta in the following manner: There is an active
absorption of urea that occurs from the collecting tubule. In the vasa recta, absorption of water into the blood takes place and return of the absorbed solute to the
interstitium follows. This is called the countercurrent exchange mechanism.