2.68b Osmoregulation

• the water coming into and out of the cells (which is isotonic) remains the same so the cells stay the same size
• the blood circulating into the tissue would be concentrated causing a hypertonic or hypotonic (dilute)  which are both undesirable as hypertonic would remove too much water and hypotonic would add too much water
• this is achieved by controlling the composition of the blood the kidney controls the composition of blood
• the excess salts and water can be excrted through the urintary
• by controlling the salts and water the kidney can keep the blood and therefore the water stays isotonic