Question

With the help of labelled diagram, explain the countercurrent mechanism of

urine concentration.​

Answer 1

Explanation:

A countercurrent mechanism system is a mechanism that expends energy to create a concentration gradient.

It is found widely in nature and especially in mammalian organs. For example, it can refer to the process that is underlying the process of urine concentration, that is, the production of hyperosmotic urine by the mammalian kidney.The ability to concentrate urine is also present in birds.

Answer 2

Counter current mechanism of urine concentration :

Explanation:

• Henle's  loop and vasa recta play an important role in this system.
• The flow of filtrate in the limbs of henle's loop and the flow of blood in the two limbs of vasa recta is in opposite direction ,thus forming a countercurrent . It maintains the gradient of increasing osmolarity of medularity of medulary interstitium.      

• In the ascending limb of henle's loop, Nacl is lost through diffusion and Na+ and Cl- ions by active transport. these are exchanged with the descending limb of vasa recta .

• Small amount of urea enter the thin segment of ascending limb which is transported back to the interstitium by collecting tubule.

• The presence of gradient helps in early passage of water from collecting tubule thereby concentrating the filtrate (urine).