Osmoregulation

Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, keeping the concentration of water and dissolved solutes within a stable range rather than letting body fluids become too dilute or too concentrated. Organisms sense osmotic changes through osmoreceptors and respond by excreting excess water, solutes, or metabolic wastes such as nitrogen compounds, typically through organs like the kidneys or skin. Both aquatic and terrestrial animals face this challenge in their own environments, and while their internal osmotic balance can fluctuate over hours or days, most organisms maintain it at a stable steady state over the longer term, making osmoregulation a basic requirement for survival.