BearCh04-ACRQedt - Chapter 04 The Action Potential Answers...

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Chapter 04 – The Action Potential Answers to Chapter Review Questions Page 1 of 3 Copyright © 2007. Lippincott Williams & Wilkins. Ancillary material to accompany Bear et al.: Neuroscience: Exploring the Brain, 3e Question 1: Define membrane potential (V m ) and sodium equilibrium potential (E Na ). Which of these, if any, changes during the course of action potential? Answer: The membrane potential (V m ) is the voltage across the neuronal membrane at any moment in time. The potential of the resting membrane is –75 mV. The sodium equilibrium potential (E Na ) is the steady equilibrium potential achieved when the membrane is permeable only to sodium ions. The value of E Na is 62 mV. However, in its resting state, the membrane is not permeable to sodium. During the application of action potential, sodium channels open and sodium rushes into the cell. The large sodium current takes the membrane potential from its negative resting state toward E Na . Sodium channels are deactivated after 1 msec, and the membrane repolarizes due to potassium efflux, which takes the membrane potential back toward the equilibrium potential of potassium. Question 2:
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This note was uploaded on 09/09/2009 for the course SPHSC 449 taught by Professor Peter during the Summer '09 term at University of Washington.

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BearCh04-ACRQedt - Chapter 04 The Action Potential Answers...

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