Which direction would Na move across the membrane if the mem

Which direction would Na+ move across the membrane if the membrane potential was 80 mV? Equilibrium potential for sodium is +60 mV

Which direction would K+ move across the membrane if the membrane potential was -80 mV? Equilibrium potential for potassium is -90 mV

Membrane potential is -70 mV.

Solution

Answer: A specific ion moving through an open ion channel causes the membrane potential to move towards the equilibrium potential for that specific ion. the membrane potential moves towards the \"average\" of the equilibrium potentials for the specific ions that can cross the membrane. The \"average\" is not a true average, but an average weighted by the relative permeabilities for the different ions -- the more permeable the membrane is for an ion, the more the equilibrium potential of that ion will influence the membrane potential. Membrane potential is -70mV. Na⁺ ion which have potential 80mv and equilibrium potential for it is +60mV then Na⁺ ion move outside the cell whereas K⁺ which is permeable to resting membrane potential moves inside the cell whose equilibrium potential is -90mV and action potential is -80mV.