Interstitial Fluid: The part of extracellular fluid that fills the spaces between most cells of the body, providing a constant environment for cells to function.
Plasma:The liquid component of blood that is part of extracellular fluid where blood cells are suspended, involved in transporting nutrients, waste products, and other substances.
Homeostasis:The process by which an organism maintains a stable internal environment despite changes in external conditions; ECF plays a critical role in this process