Answer:
Loop of Henle.
Step-by-step explanation:
Loop of Henle is a mechanism that establishes the medullary osmotic gradient, that depends on its important application in day to day life.
Moreover the loop of Henle is very very essential for concentrating the urine, they do not work at all alone. Loop of Henle looks like U shaped and it is long and it is present in birds, reptiles, and as well as mammals.