Water & Nitrogen Balance: The Kidneys [Biology only]

Water balance

• Water leaves the body through the lungs when we exhale, and water, ions and urea are lost in sweat from the skin. There is no control over these losses
• Excess water, ions and urea are removed by the kidneys in urine, and this is controlled
• If body cells lose or gain too much water by osmosis they do not function efficiently: too much water in and they swell; too much out and they shrink