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Biology: The Dynamic Science (Mind...

4th Edition
Peter J. Russell + 2 others
ISBN: 9781305389892

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BuyFindarrow_forward

Biology: The Dynamic Science (Mind...

4th Edition
Peter J. Russell + 2 others
ISBN: 9781305389892
Textbook Problem

The resting membrane potential in neurons requires:

a. membrane transport channels to be constantly open for Na+ and K+ flow.

b. the inside of neurons to be positive relative to the outside.

c. the diffusion of K+ out of the cell and a charge difference between the inside and outside of the axon set up by this movement of K+.

d. an active Na+/K+ pump, which pumps Na+ and K+ into the neuron.

e. three Na+ ions to be pumped through three Na+ gates and two K+ ions to be pumped through two K+ gates.

Summary Introduction

Introduction:

The nervous system of animals is made up of many neurons that innervate the muscle cells so that they can respond to a stimulus. The membrane of a neuron when not conducting electrical impulse exhibits resting membrane potential. In resting condition, the inside of the neuron is negatively charged (about −70 mv or millivolt) as compared to the outside of the neuron. This is due to an unequal distribution of positively charged ions such as sodium and potassium.

Explanation

Justification/explanation for the correct answer:

Option (c) states that the diffusion of K+ out of the cell causes the charge difference between two sides of the neuron. When action potential is generated in the neuron, sodium ions flow out of the neurons and the membrane potential becomes positive (+30 mv). Later when stimuli are removed, neuron again gets back to the resting condition and reaches to resting membrane potential (−70 mv). This occurs due to the outflow of potassium ions, which compensate for the inward movement of the sodium ions (Na+). Hence, the option (c) is correct.

Explanation for the incorrect answers:

Option (a) states that the resting membrane potential in neurons requires membrane transport channels to constantly open for Na+ and K+ flow. When Na+ pumps open in the neuron, Na+ flows into the cell and action potential is generated. Thereafter, potassium channel opens up and potassium flows out the cell so that resting membrane potential can be achieved. So, it is an incorrect option.

Option (c) states that the inside of the neurons should be positive relative to the outside for resting membrane potential in neurons...

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