This document discusses body fluids and fluid-electrolyte balance. It covers the sources, functions, and composition of body fluids. It describes the mechanisms of fluid movement including osmosis, diffusion, active transport, and filtration. It discusses fluid balance and the regulation of fluid balance, including the roles of thirst, ADH, and the kidneys. It also covers electrolytes like sodium, potassium, chloride, and calcium, explaining their balance and potential imbalance disorders like hypernatremia, hyponatremia, hyperkalemia, and hypokalemia.