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Difficulty: EasyNervous Coordination and Sense Organs

What is the primary physiological function of the myelin sheath surrounding axon fibers in the mammalian nervous system?

  1. To increase the speed of nerve impulse transmission along the axonAnswer
  2. B
    To synthesize and release chemical neurotransmitters into the synaptic cleft
  3. C
    To detect environmental stimuli and convert them into electrical impulses
  4. D
    To conduct nerve impulses directly toward the neuronal cell body

Answer

The primary physiological function of the myelin sheath is to increase the speed of nerve impulse transmission along the axon.
The myelin sheath provides electrical insulation along the axon, enabling action potentials to jump from one Node of Ranvier to the next in a process called saltatory conduction, which greatly increases impulse conduction speed.

Step-by-Step Solution

1
Identify the structure and composition of the myelin sheath.
The myelin sheath is a lipid-rich layer formed around nerve axons by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system.
Understanding its lipid composition clarifies its role as an electrical insulator.
2
Relate the insulating structure to nerve impulse propagation.
Depolarization occurs only at uninsulated gaps called Nodes of Ranvier, enabling action potentials to leap rapidly along the axon.
This process, known as saltatory conduction, significantly increases the velocity of nerve signal transmission.

Key Concept

Function of Myelin Sheath in Nerve Impulse Conduction
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Topics

Nervous Coordination and Sense Organs

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