Chloride is the principal anion accompanying Na+ in the extracellular fluid. Less than 15 wt % of the Cl? is associated with K+ in the intracellular fluid. Chloride passively and freely diffuses between intraand extracellular fluids through the cell membrane. If chloride diffuses freely, but most Cl? remains in the extracellular fluid, it follows that there is some restriction on the diffusion of phosphate.
