Lecture+5 - REV: Nernst vs GHK REV: REV: Action Potentials...

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Unformatted text preview: REV: Nernst vs GHK REV: REV: Action Potentials REV: Phases of the Action Potential Fig. 4‐4, p. 91 Fig. 4‐5, p. 92 Rat cardiac cell Frog twitch muscle Phases of the Action Potential (cont’d) Fig. 4‐7, p. 94 The Action Potential is directed by changes in membrane permeability Channel behavior affects firing rate • Recall Na+ channel inactivation Absolute Refractory Period • Na+ channels are inactivated • Lasts until repolarization • No stimulus can initiate another AP Relative Refractory Period Fig. 4-11, p. 99 • Some Na+ channels still inactivated • Potassium current still hyperpolarizing • Can trigger an AP with strong stimulus Action Potential Propagation Action Initiated by graded potentials Changes in Membrane Potential Fig. 4‐1, p. 88 Passive Propagation along a membrane Fig. 4‐2, p. 89 Fig. 4‐3, p. 90 • The voltage change across the membrane gets smaller with distance from the initiation zone. Action Potential Propagation (cont’d) • The spread of excitability in a neuron is directional Fig. 4‐9a, p. 97 Fig. 4‐8, p. 95 Action Potential Propagation (cont’d) Contiguous Conduction Fig. 4‐9, p. 97 ...
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This note was uploaded on 11/24/2011 for the course NPB 97952 taught by Professor ? during the Spring '09 term at UC Davis.

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