Reabsorption

Process by which the nephron removes water and solutes from the tubular fluid and returns them to the circulating blood

In renal physiology, reabsorption, more specifically tubular reabsorption, is the process by which the nephron recovers water and solutes from the tubular fluid (pre-urine) and returns them to the circulating blood. It is called reabsorption (and not absorption) because these substances have already been absorbed once from ingested food and water (particularly in the intestines) and the body is reclaiming them from a fluid stream filtered out of blood in the glomeruli that is on its way to becoming urine.