The kidneys play a very important role in osmoregulation. They are the main organs of osmoregulation in mammalian systems. The functional unit of the kidney is the nephron that filters the blood and generates urine. The kidneys regulate the water reabsorbed from the glomerulus in the kidney tubules.
They function to filter the blood and maintain the osmolality of body fluids at 300mOsm. The functions of the kidneys are controlled by hormones such as the anti-diuretic hormones (ADH), angiotensin II and aldosterone. The main function of the kidneys is to maintain the water and salt balance in the body.