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Multiple Choice
The substance of Schwann cells that insulates the axon and increases impulse speed is the:
A
neurolemma
B
axon hillock
C
nodes of Ranvier
D
myelin sheath
Verified step by step guidance
1
Step 1: Understand the role of Schwann cells in the nervous system. Schwann cells are a type of glial cell found in the peripheral nervous system. Their primary function is to produce a substance that insulates axons and facilitates faster transmission of nerve impulses.
Step 2: Learn about the myelin sheath. The myelin sheath is a fatty layer produced by Schwann cells that wraps around the axon. This insulation prevents electrical signals from dissipating and allows for rapid conduction of nerve impulses.
Step 3: Differentiate between the terms provided in the question. The neurolemma is the outermost layer of the Schwann cell, but it does not directly insulate the axon. The axon hillock is the region of the neuron where action potentials are initiated, and the nodes of Ranvier are gaps in the myelin sheath that facilitate saltatory conduction.
Step 4: Recognize that the myelin sheath is the correct answer because it is the substance produced by Schwann cells that insulates the axon and increases impulse speed.
Step 5: Review the importance of the myelin sheath in maintaining efficient communication within the nervous system. Damage to the myelin sheath can lead to neurological disorders, such as multiple sclerosis, emphasizing its critical role.