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

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

Figure 2.1 Types of neuronal electrical signals

Figure 2.2 Recording passive and active electrical signals in a nerve cell

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

Figure 2.3 Transporters and channels move ions across neuronal membranes

Figure 2.4 Electrochemical equilibrium

Nernst equation E k = 58/z * log [K] 2 /[K] 1 = 58 log 1/10 = -58 mV

Figure 2.5 Membrane potential influences ion fluxes

Goldman equation – multiple ionic species and permeabilities V = 58 log (P K [K] 2 +P Na [Na] 2 +P Cl [Cl] 1 (P K [K] 1 +P Na [Na] 1 +P Cl [Cl] 2 E k = 58/z * log [K] 2 /[K] 1 = 58 log 1/10 = -58 mV Reduces to Nernst if only one ion present or permeable…

Figure 2.6 Resting and action potentials arise from differential permeability to ions

Figure 2.7 Resting membrane potential is determined by the K + concentration gradient

Box 2A The Remarkable Giant Nerve Cells of Squid

Figure 2.8 The role of Na + in the generation of an action potential in a squid giant axon

Box 2B Action Potential Form and Nomenclature

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

Box 3A The Voltage Clamp Technique

Figure 3.1 Current flow across a squid axon membrane during a voltage clamp experiment

Figure 3.2 Current produced by membrane depolarizations to several different potentials

Figure 3.3 Relationship between current amplitude and membrane potential

Figure 3.4 Dependence of the early inward current on sodium

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

Figure 3.5 Pharmacological separation of Na + and K + currents

Figure 3.6 Membrane conductance changes underlying the action potential are time- and voltage- dependent

Figure 3.7 Depolarization increases Na + and K + conductances of the squid giant axon

Figure 3.8 Mathematical reconstruction of the action potential

Box 3B Threshold

Figure 3.10 Passive current flow in an axon

Box 3C(1) Passive Membrane Properties

Box 3C(2) Passive Membrane Properties

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

Figure 3.11 Propagation of an action potential

Figure 3.12 Action potential conduction requires both active and passive current flow

Figure 3.12 Action potential conduction requires both active and passive current flow (Part 2)

Figure 3.13 Saltatory action potential conduction along a myelinated axon

Figure 3.13 Saltatory action potential conduction along a myelinated axon (Part 1)

Figure 3.13 Saltatory action potential conduction along a myelinated axon (Part 2)

Figure 3.13 Saltatory action potential conduction along a myelinated axon (Part 3)

Figure 3.14 Speed of action potential conduction in unmyelinated versus myelinated axons

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

Figure 4.1 Patch clamp measurements of ionic currents through single Na + channels

Box 4A The Patch Clamp Method

Figure 4.2 Patch clamp measurements of ionic currents through single K + channels (Part 1)

Figure 4.2 Patch clamp measurements of ionic currents through single K + channels (Part 2)

Figure 4.3 Functional states of voltage-gated Na + and K + channels

Figure 4.4 Types of voltage-gated ion channels

Figure 4.5 Diverse properties of K + channels

Figure 4.6 Topology of principal subunits of voltage-gated Na +, Ca 2+, K +, and Cl – channels

Box 4C Toxins That Poison Ion Channels

Figure 4.7 A charged voltage sensor permits voltage-dependent gating of ion channels

Box 4D(1) Diseases Caused by Altered Ion Channels

Box 4D(2) Diseases Caused by Altered Ion Channels

Figure 4.10 Examples of ion transporters found in cell membranes (Part 1)

Figure 4.10 Examples of ion transporters found in cell membranes (Part 2)

Figure 4.11 Ion movements due to the Na + /K + pump

Figure 4.12 Electrogenic transport of ions by the Na +/ K + pump can influence membrane potential