EMBRYOLOGY
NERVOUS SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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more rapidly in myelinated than in non-myelinated axons.
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by reversing the concentration gradients for sodium and potassium ions
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more slowly in axons of large than in small diameter
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by the direct action of acetylcholine on the axonal membrane
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Detailed explanation-1: -The presence of myelin leads to a significant increase in action potential conduction speed compared to an unmyelinated axon. For a myelinated axon, the action potential “jumps” between Nodes of Ranvier in a process called saltatory conduction.
Detailed explanation-2: -Myelinated neurons conduct impulses faster than unmyelinated neurons because nerve impulses jump over the myelin sheath rather than travel through it, making the distance to the axon terminal shorter. This occurs due to the large proportion of fatty substances that make up the myelin sheath.
Detailed explanation-3: -In unmyelinated axons, the action potential travels smoothly, with constant shape and at constant velocity. In myelinated axons, conduction is saltatory: The action potential “jumps” nearly instantaneously from one node of Ranvier to the next, greatly increasing the speed of propagation.