PHYSIOLOGY
CENTRAL NERVOUS SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Occurs only in the myelin sheath is continuous
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Occurs only in the nodes of Ranvier
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Occurs only in the absence of axon hillocks
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Is faster that conduction of an unmyelinated fiber
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Detailed explanation-1: -Saltatory conduction is faster compared to an unmyelinated neuron because it prevents diffusion of the electrical signal through the membrane and allows the action potential to “jump” down the axon.
Detailed explanation-2: -Saltatory conduction is faster because the action potential basically jumps from one node to the next (saltare = “to leap”), and the new influx of Na+ renews the depolarized membrane. Along with the myelination of the axon, the diameter of the axon can influence the speed of conduction.
Detailed explanation-3: -By acting as an electrical insulator, myelin greatly speeds up action potential conduction (Figure 3.14). For example, whereas unmyelinated axon conduction velocities range from about 0.5 to 10 m/s, myelinated axons can conduct at velocities up to 150 m/s.