Zoe MCQ 02

Topic: Anatomy

Created on Saturday, November 26 2022 by zoe

Last modified on Saturday, November 26 2022.

 
        A) An interval of time during which a second action potential cannot be initiated, during which some, but not all potassium channels have returned to a resting state
 
        B) An interval of time during which a second action potential cannot be initiated, during which some, but not all sodium channels have returned to a resting state
 
        C) An interval of time during which a second action potential cannot be initiated, due to so many sodium channels being inactivated
 
        D) An interval of time during which a second action potential cannot be initiated, due to so many potassium channels being inactivated
 

 

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This question was created on November 26, 2022 by zoe.
This question was last modified on November 26, 2022.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWERS AND EXPLANATIONS

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A) An interval of time during which a second action potential cannot be initiated, during which some, but not all potassium channels have returned to a resting state

This answer is incorrect.

Again, that is the definition of the relative refractory period, which follows the absolute refractory period. This also has to do with sodium channels, not potassium  (See References)

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B) An interval of time during which a second action potential cannot be initiated, during which some, but not all sodium channels have returned to a resting state

This answer is incorrect.

That is the definition of the relative refractory period, which follows the absolute refractory period. In the relative refractory period, some, but not all sodium channels have returned to a resting state. A larger % of this reduced population of Na+ channels must be activated to initate an impulse   (See References)

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C) An interval of time during which a second action potential cannot be initiated, due to so many sodium channels being inactivated

This answer is correct.

The absolute refractory period is during a brief period following the peak of an action potential, so many Na+ channels are inactivated that another impulse cannot be generated no matter how much the membrane is depolarized   (See References)

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D) An interval of time during which a second action potential cannot be initiated, due to so many potassium channels being inactivated

This answer is incorrect.

The absolute refractory period is during a brief period following the peak of an action potential, so many Na+ channels are inactivated that another impulse cannot be generated no matter how much the membrane is depolarized. Not potassium.   (See References)

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References:

1. Nolte: Chapter 7

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anatomy
Zoe MCQ 02
Question ID: 112622074
Question written by zoe. (C) FrontalCortex.com 2006-2009, all rights reserved. Created: 11/26/2022
Modified: 11/26/2022
Estimated Permutations: 24