In human respiration (Glucose + Oxygen = Carbon Dioxide + Water + Energy) why is it necessary to take in water and why is it necessary to excrete it?
A. In general terms, most of the processes within the human body depend on aqueous solutions or suspensions, so the body needs to maintain its water level. The human excretory system, in particular, uses water as the medium for ridding the body of urea (a nitrogenous waste product from the metabolism of protein) and other wastes; urine, for example, is about 96 percent water. Sweating, another important bodily process requiring water, is used to regulate body temperature and excrete metabolic wastes. More water is lost from the lungs and digestive tract. So water must be taken in to replace that which is lost. (source: Claude A. Villee, Biology, W.B. Saunders Co., Philadelphia and London, copyright 1957.
