Translucent NEPHRON from a Human Kidney (the kidneys are paired organs that are responsible for controlling fluid balance and for the excretion of nitrogenous and other wastes via urine). The nephron consists of a long and twisted tube which, at its proximal end, is blind and invaginated to create a double walled cup (Bowman's Capsule) which surrounds a clump of fine blood vessels (the glomerulus). From the glomerulus, passes the filtrate from the blood which enters the cavity of the tubule. First it passes through the proximal convoluted tubule (shown in blue) where a considerable amount of resorption occurs. Thence through the Loop of Henle (green), where further concentration occurs. The distal convoluted tubule sees active ion transport. Ultimately, the fluid in the tubule becomes urine and passes down the collecting duct to the urinary bladder.