Osmotic pressure

Osmotic pressure is the primary determinant of the distribution of water among the three major compartments.is like a magenet of water :)  The concentrations of the major solutes in these flids differ, with each compartment having one solute that is primarily limited to that compartment and therefore determines its osmotic pressure. The intracellular flid the potassium (K+) is major (most of the cell Mg2+ is bound and osmotically inactive) and in the extracellular compartment, Na+ salts predominate in the interstitial side, and proteins in the plasma