A failure of homeostasis -- the balance of essential physiological states -- means disaster for the organism. Failure to maintain body temperature leads to hypothermia or heatstroke. Failure to maintain energy balance can result in obesity and diabetes. Failure to maintain calcium balance in the blood leads to hypocalcemia or hypercalcemia. Failure to maintain water balance results in dehydration or hyperhydration. In each case, extremes are potentially dangerous.
