The document discusses water and electrolyte balance in the human body. It explains that water makes up around 75% of body weight at birth and 55-60% in adults, distributed between intracellular and extracellular fluid compartments. Total body water intake and output is normally around 2,500 mL per day. Key electrolytes like sodium, potassium, and calcium are also discussed in terms of their roles, homeostasis, and potential imbalances. The kidneys, hormones, and fluid compartment exchanges all work to maintain balance.

1. BALANCE WATER ACID-BASE ELECTROLYTE