In the kidney, the<unk>  () (or<unk> 's<unk> ,<unk> <unk> , nephron<unk>  or its Latin counterpart ansa nephroni) is the portion of a nephron that leads from the proximal convoluted tubule to the distal convoluted tubule. Named after its discoverer, the German anatomist Friedrich Gustav Jakob<unk> , the<unk> 's main function is to create a concentration gradient in the medulla of the kidney. By means of a countercurrent multiplier system, which uses electrolyte pumps, the<unk>  creates an area of high urea concentration deep in the medulla, near the papillary duct in the collecting duct system. Water present in the filtrate in the papillary duct flows through aquaporin channels out of the duct, moving passively down its concentration gradient. This process reabsorbs water and creates a concentrated urine for excretion.
Loop of Henle
Crypts of Henle
Glomerular basement membrane
Adrenal cortex
Bowman's capsule
Reticuloendothelial system
Reticular membrane
Node of Ranvier