Fig. 48-4DendritesStimulusNucleusCellbodyAxonhillockPresynapticcellAxonSynaptic terminalsSynapsePostsynaptic cellNeurotransmitterFig. 48-6aOUTSIDECELL [K+]5 mM [Na+]150 mM [Cl–]120 mMINSIDECELL [K+]140 mM [Na+]15 mM [Cl–]10 mM [A–]100 mM(a)Fig. 48-6b(b)OUTSIDECELLNa+KeyK+Sodium-potassiumpumpPotassiumchannelSodiumchannelINSIDECELLFig. 48-7aInnerchamberOuterchamber–90 mV140 mM5 mMKCIKCIK+Cl–Potassiumchannel(a) Membrane selectively permeable to K+EK = 62 mV(log5 mM140 mM)= –90 mVFig. 48-7b(b) Membrane selectively permeable to Na++62 mV15 mMNaCICl–150 mMNaCINa+SodiumchannelENa = 62 mV(log150 mM15 mM= +62 mV)Fig. 48-7InnerchamberOuterchamber–90 mV140 mM5 mMKCIKCIK+Cl–Potassiumchannel(a) Membrane selectively permeable to K+(b) Membrane selectively permeable to Na++62 mV15 mMNaCICl–150 mMNaCINa+SodiumchannelEK = 62 mV(log5 mM140 mM)= –90 mVENa = 62 mV(log150 mM15 mM= +62 mV)Fig. 48-8TECHNIQUEMicroelectrodeVoltagerecorderReferenceelectrodeFig. 48-9Stimuli+50+50Stimuli00Membrane potential (mV)Membrane potential (mV)–50–50Threshold ThresholdRestingpotentialRestingpotentialHyperpolarizations–100 –10001 2 345Time (msec)(a) Graded hyperpolarizationsTime (msec)(b) Graded depolarizationsDepolarizations012 3 45Strong depolarizing stimulus+500Membrane potential (mV)–50ThresholdRestingpotential–100Time (msec)0 12345 6(c) Action potentialActionpotentialFig. 48-10-1KeyNa+K++50ActionpotentialThreshold01451–50Resting potentialMembrane potential(mV)–100TimeExtracellular fluidPlasmamembraneCytosolInactivation loopResting stateSodiumchannelPotassiumchannelDepolarization231Fig. 48-10-2KeyNa+K++50ActionpotentialThreshold01451–50Resting potentialMembrane potential(mV)–100TimeExtracellular fluidPlasmamembraneCytosolInactivation loopResting stateSodiumchannelPotassiumchannelDepolarization2321Fig. 48-10-3KeyNa+K++50ActionpotentialThreshold01451–50Resting potentialMembrane potential(mV)–100TimeExtracellular fluidPlasmamembraneCytosolInactivation loopResting stateSodiumchannelPotassiumchannelDepolarizationRising phase of the action potential23213Fig. 48-10-4KeyNa+K++50ActionpotentialThreshold01451–50Resting potentialMembrane potential(mV)–100TimeExtracellular fluidPlasmamembraneCytosolInactivation loopResting stateSodiumchannelPotassiumchannelDepolarizationRising phase of the action potentialFalling phase of the action potential232134Fig. 48-10-5KeyNa+K++50ActionpotentialThreshold01451–50Resting potentialMembrane potential(mV)–100TimeExtracellular fluidPlasmamembraneCytosolInactivation loopResting stateSodiumchannelPotassiumchannelDepolarizationRising phase of the action potentialFalling phase of the action potential5Undershoot232134Fig. 48-10-5KeyNa+K++50ActionpotentialThreshold01451–50Resting potentialMembrane potential(mV)–100TimeExtracellular fluidPlasmamembraneCytosolInactivation loopResting stateSodiumchannelPotassiumchannelDepolarizationRising phase of the action potentialFalling phase of the action potential5Undershoot232134Fig. 48-11-1AxonPlasmamembraneCytosolActionpotentialNa+Fig. 48-11-2AxonPlasmamembraneCytosolActionpotentialNa+ActionpotentialNa+K+K+Fig. 48-11-3AxonPlasmamembraneCytosolActionpotentialNa+ActionpotentialNa+K+K+ActionpotentialK+K+Na+Fig. 48-12aAxonMyelin sheathSchwanncellNodes ofRanvierSchwanncellNucleus ofSchwann cellNode of RanvierLayers of myelinAxonFig. 48-12bMyelinated axon (cross section)0.1 µmFig. 48-13Cell bodySchwann cellDepolarized region(node of
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