3 Membrane and Action Potentials

3 Membrane and Action Potentials - Membrane and Action...

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Membrane and Action Potentials Reading: Squire ch 6
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Squid giant axon film Which ions contribute to each portion of the action potential curve? Na+ K+ Cl-
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-102mV gK = conductance of potassium ~ reflection of # of open channels E K+ = -102mV E Na+ = 56mV E Cl- = -76mV E Ca+ = 125mV resting membrane potential = -70mV What is the effect on the membrane potential if g for each ion was increased? K Cl Na Ca Moves out of cell -slight hyperpolarization Moves out of cell -hyperpolarizes Moves into cell - depolarizes Moves into cell - depolarizes
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Increasing gK for a given ion, while the membrane potential is held constant at the E K , doesn’t alter membrane potential This situation “locks” membrane potential near E K by reducing the ability of other ions to alter the potential
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Voltage-Clamp Technique
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Depolarizing the squid axon tetrodotoxin tetraethylammonium
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An AP is associated with a sequential increase in the conduction (g) for Na and K ions Inward flow of Na dominates until it is matched by the outward flow of K Na channels open, are inactivated, then close K channels – delayed rectifiers
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This note was uploaded on 04/04/2008 for the course BIOLOGY 410 taught by Professor Butcher during the Spring '06 term at Centenary LA.

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3 Membrane and Action Potentials - Membrane and Action...

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