title: Fluid and electrolyte disorders. Sodium.
abstract: Because water is freely exchangeable across most cell membranes, its distribution is largely determined by physical factors and by the relative osmolal concentrations of the extracellular and intracellular fluids. As the major extracellular cation, sodium is a principal determinant of the extracellular fluid volume.
mesh_terms: D006728:Hormones / Q000378:metabolism; D006801:Humans; D006955:Hypernatremia / Q000378:metabolism / Q000628:therapy; D007010:Hyponatremia / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D014883:Water-Electrolyte Imbalance / Q000378:metabolism*
chemical_list: D006728:Hormones; D012964:Sodium