NRSC 2100 1st Edition Lecture 5 The Ionic Basis of The Resting Membrane Potential Membrane potential Vm Voltage across the neuronal membrane lipid bilayer Measured value in most neurons at rest approximately 65 mV Resting Membrane Potential value can be derived from all Eions Relative Ion Permeabilities of the Membrane at Rest Neurons permeable to more than one type of ion Membrane permeability determines membrane potential Goldman equation Takes into account permeability of membrane to different ions Vm 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 it is mostly permeable to K Membrane potential sensitive to extracellular K Increased extracellular K depolarizes membrane potential Resting Membrane Potential Summary sets the stage for neural communication FORCES THAT MAINTAIN THE RESTING MEMBRANE POTENTIAL Passive forces uses no energy Diffusion and Electrical forces Active forces uses energy ATP Na K pump linked transport pumps 3 Na out for every 2 K pumped in against diffusion electrical gradients
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