A: Presence of myelin sheath increases the ra | vedclass

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(A) The myelin sheath acts as an electrical insulator around the axon.Because of this insulation,ionic channels (voltage-gated $Na^+$ channels) are la

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(A) The myelin sheath acts as an electrical insulator around the axon.Because of this insulation,ionic channels (voltage-gated $Na^+$ channels) are largely absent in the internodal regions covered by the myelin sheath.Consequently,depolarization can only occur at the nodes of Ranvier,where these channels are highly concentrated.This forces the action potential to 'jump' from one node to the next,a process known as saltatory conduction,which significantly increases the speed of nerve impulse transmission.

$A$: 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.

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$A$: 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.