I. Water Gains and Losses 1. Evaporation occurs from respiratory surfaces.
Evaporation occurs through the skin.
Sweating occurs on the skin surface. Elimination of water in feces is a normal occurrence. The nervous system regulates these processes by regulation of thirst and temperature control. Nutrients, mineral ions, drugs, and food additives are absorbed by the gastrointestinal tract. Secretion from endocrine glands adds hormones.