Question

what is the cpuntercurrent multiplication ?

Answer 1

Countercurrent multiplication is a process which eastablish a concentration gradient by using eenergy. This process is widely present in nature and also present in organs of mammles. Most common example is kidney where concentrated urine is produced in the nephron by countercurrent multiplication. In the nephron the descending loop of Henle is permeable to water and impermeable to solution and thus water easily reabsorbed here resulting into concentrated urine. This concentrated urine is passed to the ascending loop of Henle which is impermeable to water and permeable to solute. Thus , ions are reabsorbed here resulting into dilution of urine and increased osmolarity of interstitial fluids leading to water reabsorption and finally urine becomes highly concentrated.