Countercurrent multiplication- It is a mechanism that expands energy to create a concentration gradient. It is found widely in nature and especially in mammalian organs.

Eg. It can refer to a process that is underlying the process of urine concentration that is the production of hyperosmotic urine by mammalian kidney.

countercurrent mechanism- It includes both countercurrent multiplier and countercurrent exchanger. The first takes place in the region of nephron called Henles loop and second in a region of peritubular cappilary bed called vasa recta. Both are involved in establishing an osmotic gradient throughout this region.