If two liters of water are taken, the water is distributed rapidly throughout the body. The kidney responds to the increased water intake after about 15-30 minutes. The flow of urine rises from the normal value 50 ml per hour to its peak of 1500 ml per hour. The extra water is excreted by the kidney within three hours. The excess urine output may be almost equal to the water ingested. In tropical climate, a greater part of the ingested water is lost in the sweat.
Effects of Water Deprivation/Loss on Water Balance
Water is being constantly lost from the human body in the form of urine, sweat, faeces and expired air. If corresponding amounts of water are not ingested, water depletion occurs in the body leading to change in the body fluids. A reduction in volume of the extra cellular fluid and intracellular fluid takes place. The urine output is reduced. There is a rapid decrease in body weight and a state of dehydration of the cells occurs. After a few days, a decrease in plasma volume occurs which will reduce cardiac output and lead to circulatory failure. An adult who has lost 5-10 liters of water from the body will be seriously ill and death will occur when the water loss from the body is about 15 liters.