<prompt> Most diffusable ion in excitable tissue is -NaKPO4-Cl-  <response>: Points to noteConcentration of ionsNa concentration higher in ECF K concentration higher in ICF Cl- concentration higher in ECFK leak channels allow K to move from ICF to ECFNa is prevented from entering the cell.Thus diffusion is highest for K, then Cl- and least for Na, when the cell is at rest. 