$A$: Presence of myelin sheath increases the rate of conduction of nerve impulse.
$R$: Ionic channels are absent in the area covered by myelin sheath; therefore,depolarization occurs only at the nodes of Ranvier,resulting in saltatory or jumping conduction.
$R$: Ionic channels are absent in the area covered by myelin sheath; therefore,depolarization occurs only at the nodes of Ranvier,resulting in saltatory or jumping conduction.
- AAssertion and Reason both are correct and Reason is the correct explanation of Assertion.
- BAssertion and Reason both are correct but Reason is not the correct explanation of Assertion.
- CAssertion is correct,but Reason is incorrect.
- DBoth Assertion and Reason are incorrect.
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Propagation of action potential is very fast in nerve fibres which have
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View SolutionConsider the statements as True/False:
$I$. The axoplasm inside the axon contains a high concentration of $K^{+}$ and negatively charged proteins.
$II$. The axoplasm inside the axon contains a low concentration of $Na^{+}$.
$III$. The fluid outside the axon contains a low concentration of $K^{+}$.
$IV$. The fluid outside the axon contains a high concentration of $Mg^{++}$ and negatively charged proteins.
The correct option is:
$I$. The axoplasm inside the axon contains a high concentration of $K^{+}$ and negatively charged proteins.
$II$. The axoplasm inside the axon contains a low concentration of $Na^{+}$.
$III$. The fluid outside the axon contains a low concentration of $K^{+}$.
$IV$. The fluid outside the axon contains a high concentration of $Mg^{++}$ and negatively charged proteins.
The correct option is:
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View Solution$A$: In the nervous system,the generation of an action potential depends upon the influx of sodium ions into the axoplasm.
$R$: The influx of sodium ions during nerve impulse generation is due to the efflux of potassium ions.
$R$: The influx of sodium ions during nerve impulse generation is due to the efflux of potassium ions.
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