Self-regulation of the body with a lack of water.

Although most of the intake comes through the digestive tract, about 230 ml per day is generated metabolically, in the last stages of aerobic respiration. In addition, every day about 2500 ml of water leaves the body through different routes; most of this wasted water is eliminated as urine. The kidneys can also regulate blood volume, as can the mechanisms that drain water from filtrate and urine. The kidneys can regulate water levels in the body; they retain water if you are dehydrated, and they can dilute the urine to eliminate excess water if necessary. Water is lost through the skin by evaporation from the surface of the skin without open sweating and from air expelled from the lungs.