Membrane potential (Vm): Voltage across the neuronal membrane (lipid bilayer);Measured value in most neurons at rest: approximately -65 mVResting Membrane Potential value can be derived from all Eions Relative Ion Permeabilities of the Membrane at RestNeurons permeable to more than one type of ionMembrane permeability determines membrane potentialGoldman equationTakes into account permeability of membrane to different ionsVm = 2.303 RT log (PK[K+]o + PNa[Na+]o + PCl[Cl-]i)F (PK[K+]i + PNa[Na+]i + PCl[Cl-]o)The Resting Membrane PotentialImportant points about membrane potentialsPump proteins maintain ionic concentration differences between inside and outside of neurons (sodium-potassium pump and calcium pumps);Large changes in VmMinuscule changes in ionic concentrations;Net difference in electrical chargeInside and outside membrane surface (capacitance);Rate of movement of ions across membraneProportional to force (Vm – Eion)The Ionic Basis of The Resting Membrane PotentialRelative Ion Permeabilities of the Membrane at RestResting membrane potential is close to EK because it is mostly permeable to K+Membrane potential sensitive to extracellular K+Increased extracellular K+ depolarizes membrane potentialResting Membrane Potential Summary:“sets the stage for neural communication”FORCES THAT MAINTAIN THE RESTING MEMBRANE POTENTIAL:Passive forces - uses no energyDiffusion and Electrical forcesActive forces – uses energy (ATP)Na+/K+ pump = linked transport – pumps 3 Na+ out forevery 2 K+ pumped in (against diffusion & electrical gradients).NRSC 2100 1st Edition Lecture 5The Ionic Basis of The Resting Membrane PotentialMembrane potential (Vm): Voltage across the neuronalmembrane (lipid bilayer);• Measured value in most neurons at rest: approximately-65 mVResting Membrane Potential value can be derived from allEions Relative Ion Permeabilities of the Membrane atRest– Neurons permeable to more than one type of ion– Membrane permeability determines membrane potential – Goldman equation• Takes into account permeability of membrane to different ionsVm = 2.303 RT log (PK[K+]o + PNa[Na+]o + PCl[Cl-]i)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.F (PK[K+]i + PNa[Na+]i + PCl[Cl-]o)The Resting Membrane Potential • Important points about membrane potentials• Pump proteins maintain ionic concentration differences between inside and outside of neurons (sodium-potassium pump and calcium pumps);• Large changes in Vm– Minuscule changes in ionic concentrations;• Net difference in electrical charge– Inside and outside membrane surface (capacitance);• Rate of movement of ions across membrane– Proportional to force (Vm – Eion)The Ionic Basis of The Resting Membrane Potential • Relative Ion Permeabilities of the Membrane at Rest– Resting membrane potential is close to EK because itis mostly permeable to K+ – Membrane potential sensitive to extracellular K+ – Increased extracellular K+ depolarizes membrane potentialResting Membrane Potential Summary: “sets the stage for neural communication”FORCES THAT MAINTAIN THE RESTING MEMBRANE POTENTIAL:Passive forces - uses no energyDiffusion and Electrical forcesActive forces – uses energy (ATP)Na+/K+ pump = linked transport – pumps 3 Na+ out forevery 2 K+ pumped in (against diffusion & electrical