Question: where is water not reabsorbed in the nephron

title: Reabsorption
text: In renal physiology , reabsorption or tubular reabsorption is the process by which the nephron removes water and solutes from the tubular fluid ( pre-urine ) and returns them to the circulating blood . It is called reabsorption ( and not absorption ) both because these substances have already been absorbed once ( particularly in the intestines ) and because the body is reclaiming them from a post glomerular fluid stream that is well on its way to becoming urine ( that is , they will soon be lost to the urine unless they are reclaimed ) . Substances are reabsorbed from the tubule into the peritubular capillaries . This happens as a result of sodium transport from the lumen into the blood by the Na / K ATPase in the basolateral membrane of the epithelial cells . Thus , the glomerular filtrate becomes more concentrated , which is one of the steps in forming urine . Reabsorption allows many useful solutes ( primarily glucose and amino acids ) , salts and water that have passed through Bowman 's capsule , to return to the circulation . These solutes are reabsorbed isotonically , in that the osmotic potential of the fluid leaving the proximal convoluted tubule is the same as that of the initial glomerular filtrate . However , glucose , amino acids , inorganic phosphate , and some other solutes are reabsorbed via secondary active transport through cotransport channels driven by the sodium gradient .