1. Outline
Neuronal excitability Nature of neuronal electrical signals Convey information over distances Convey information to other cells via synapses Signals depend on changes in electrical potential Resting potential concepts Action potential Properties of action potentials (APs) Dynamics of potential explained by changes in Na+ and K+ permeabilities Voltage clamp (review) Na+ channel activation and inactivation kinetics K+ channel activation (and inactivation) kinetics AP propagation Ion transporters and Ion channels Complementary functions to maintain and use electrochemical gradient Transporters… Generate concentration gradients Channels… Use concentration gradients to make electrical signals

2. Outline
Neuronal excitability Nature of neuronal electrical signals Convey information over distances Convey information to other cells via synapses Signals depend on changes in electrical potential Resting potential concepts Action potential Properties of action potentials (APs) Dynamics of potential explained by changes in Na+ and K+ permeabilities Voltage clamp (review) Na+ channel activation and inactivation kinetics K+ channel activation (and inactivation) kinetics AP propagation Ion transporters and Ion channels Complementary functions to maintain and use electrochemical gradient Transporters… Generate concentration gradients Channels… Use concentration gradients to make electrical signals

3. Figure 2.1 Types of neuronal electrical signals
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4. Figure 2.2 Recording passive and active electrical signals in a nerve cell
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5. Outline
Neuronal excitability Nature of neuronal electrical signals Convey information over distances Convey information to other cells via synapses Signals depend on changes in electrical potential Resting potential concepts Action potential Properties of action potentials (APs) Dynamics of potential explained by changes in Na+ and K+ permeabilities Voltage clamp (review) Na+ channel activation and inactivation kinetics K+ channel activation (and inactivation) kinetics AP propagation Ion transporters and Ion channels Complementary functions to maintain and use electrochemical gradient Transporters… Generate concentration gradients Channels… Use concentration gradients to make electrical signals

6. Figure 2.3 Transporters and channels move ions across neuronal membranes
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7. Figure 2.4 Electrochemical equilibrium
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8. Ek = 58/z * log [K]2/[K]1 = 58 log 1/10 = -58 mV
Nernst equation
Ek = 58/z * log [K]2/[K]1 = 58 log 1/10 = -58 mV

9. Figure 2.5 Membrane potential influences ion fluxes
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10. Goldman equation – multiple ionic species and permeabilities
(PK[K]2+PNa[Na]2+PCl[Cl]1
V = 58 log
(PK[K]1+PNa[Na]1+PCl[Cl]2
Reduces to Nernst if only one ion present or permeable…
Ek = 58/z * log [K]2/[K]1 = 58 log 1/10 = -58 mV

11. Figure 2.6 Resting and action potentials arise from differential permeability to ions
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13. Figure 2.7 Resting membrane potential is determined by the K+ concentration gradient
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14. Box 2A The Remarkable Giant Nerve Cells of Squid
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15. Figure 2.8 The role of Na+ in the generation of an action potential in a squid giant axon
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16. Box 2B Action Potential Form and Nomenclature
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17. Outline
Neuronal excitability Nature of neuronal electrical signals Convey information over distances Convey information to other cells via synapses Signals depend on changes in electrical potential Resting potential concepts Action potential Properties of action potentials (APs) Dynamics of potential explained by changes in Na+ and K+ permeabilities Voltage clamp (review) Na+ channel activation and inactivation kinetics K+ channel activation (and inactivation) kinetics AP propagation Ion transporters and Ion channels Complementary functions to maintain and use electrochemical gradient Transporters… Generate concentration gradients Channels… Use concentration gradients to make electrical signals

18. Box 3A The Voltage Clamp Technique
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19. Figure 3.1 Current flow across a squid axon membrane during a voltage clamp experiment
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20. Figure 3.2 Current produced by membrane depolarizations to several different potentials
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21. Figure 3.3 Relationship between current amplitude and membrane potential
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22. Figure 3.4 Dependence of the early inward current on sodium
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23. Outline
Neuronal excitability Nature of neuronal electrical signals Convey information over distances Convey information to other cells via synapses Signals depend on changes in electrical potential Resting potential concepts Action potential Properties of action potentials (APs) Dynamics of potential explained by changes in Na+ and K+ permeabilities Voltage clamp (review) Na+ channel activation and inactivation kinetics K+ channel activation (and inactivation) kinetics AP propagation Ion transporters and Ion channels Complementary functions to maintain and use electrochemical gradient Transporters… Generate concentration gradients Channels… Use concentration gradients to make electrical signals

24. Figure 3.5 Pharmacological separation of Na+ and K+ currents
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25. Figure 3.6 Membrane conductance changes underlying the action potential are time- and voltage-dependent
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26. Figure 3.7 Depolarization increases Na+ and K+ conductances of the squid giant axon
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27. Figure 3.8 Mathematical reconstruction of the action potential
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28. Box 3B Threshold
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29. Figure 3.10 Passive current flow in an axon
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30. Box 3C(1) Passive Membrane Properties
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31. Box 3C(2) Passive Membrane Properties
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