PHYL1010 010 Notes to Remember on Resting Membrane Potential.pdf

Neuroscience I NOTES TO REMEMBER ON THE RESTING MEMBRANE POTENTIAL The Goldman Equation relates membrane potential, V, to the concentration gradient of, and membrane permeability to K+, Na+, and Cl- ions. It is derived by working out the membrane potential at which the fluxes of positive and negativ...

Neuroscience I NOTES TO REMEMBER ON THE RESTING MEMBRANE POTENTIAL The Goldman Equation relates membrane potential, V, to the concentration gradient of, and membrane permeability to K+, Na+, and Cl- ions. It is derived by working out the membrane potential at which the fluxes of positive and negative ions balance perfectly, so that the net current flow will be zero, and the system will be in equilibrium. Therefore, at equilibrium (the resting potential), there may be continuous movement of given positive and negative ions into or out of the cell, however, the overall current flow is zero. The Goldman Equation differs from the Nernst Equation, in that the Nernst Equation: Considers only one ion at a time Does not take into account the differing permeabilities of the membrane to different ions. Assumes that the ions are in equilibrium, so that there will be no net flow of any given ions The Goldman Equation is written: Notice that for the positive ions, the extracellular concentration is in the numerator (e.g. K o) while for the negatively charged Cl- ion, it is the denominator. This is because z (the ionic charge) for the chloride is negative, and the inverse of a log is the same as the log times –1. Since, Ko is much smaller than Ki, then [Ko/Ki] will be