03 -- electrophysiology 2

03 -- electrophysiology 2 - Changes in the Resting Membrane...

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Changes in the Resting Membrane Potential
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Changing the potential across a membrane KEY POINT: THE SENDING, RECEIVING AND INTEGRATION OF “SIGNALS” “SIGNALS” BY NEURONS IS ACCOMPLISHED BY ALTERING THE MEMBRANE POTENTIAL ALTERING THE MEMBRANE POTENTIAL
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Before we begin… Some terminology Alteration of the membrane potential such that the INSIDE becomes less negative less negative = depolarization depolarization Alteration of the membrane potential such that the INSIDE becomes more negative more negative = hyperpolarization hyperpolarization
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Altering the Potential Can be produced by 2 events: A. Changing the concentration of an ion or ions on the two sides of the membrane If the body increases the uptake or ingestion of ions, the extracellular conc. of those ions will increase If body cells rupture, intracellular ions will be released into the extracellular fluid, this increasing their conc. ** these events are not common and do not occur within a time-scale that allows them play a significant role in neural signaling A. Changing the permeability of the membrane to one or more ions Adding / removing channels for diffusion (leak channels) Altering the state of “changeable” channels (gated channels) Altering the state of “changeable” channels (gated channels) THIS IS THE MAIN WAY IN WHICH NEURAL SIGNALING OCCURS! THIS IS THE MAIN WAY IN WHICH NEURAL SIGNALING OCCURS!
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Gated Ion Channels Besides channels for diffusion (“leak channels”) that are always open, there are other transmembrane proteins that act as channels but which are not always open Channels that “respond” (open/close) to various chemicals Called LIGAND GATED LIGAND GATED or CHEMICALLY REGULATED CHEMICALLY REGULATED
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Gated Ion Channels Besides channels for diffusion (“leak channels”) that are always open, there are other transmembrane proteins that act as channels but which are not always open Channels that “respond” (open/close) to physical forces Called MECHANICALLY GATED MECHANICALLY GATED or MECHANICALLY REGULATED MECHANICALLY REGULATED
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Gated Ion Channels Besides channels for diffusion (“leak channels”) that are always open, there are other transmembrane proteins that act as channels but which are not always open Channels that “respond” (open/close) to changes in the membrane potential Called VOLTAGE GATED VOLTAGE GATED or VOLTAGE REGULATED VOLTAGE REGULATED
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Altering the Potential Changes in the membrane potential as the result of opening/closing gated ion channels occur in two very different ways, based on: what gated channels are opening and/or closing where in the neuron the stimulus is occurring
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Altering the Potential GRADED POTENTIALS
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This note was uploaded on 03/23/2009 for the course BIOL 450 taught by Professor Jeremyingraham during the Spring '09 term at UNC.

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03 -- electrophysiology 2 - Changes in the Resting Membrane...

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