Multiple Choice
Which of the following best characterizes depolarization, the first phase of the action potential in a neuron?
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45. Nervous System
Neurons and Action Potentials
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Which of the following best describes a key difference between a typical neuron and a neuron affected by multiple sclerosis (MS)?
A
Typical neurons lack voltage-gated sodium channels along the axon.
B
Typical neurons have more dendrites than neurons affected by MS.
C
Neurons affected by MS have damaged myelin sheaths, leading to slower action potential conduction.
D
Neurons affected by MS have increased neurotransmitter release at synapses.
Verified step by step guidance1
Understand the role of myelin sheaths in a typical neuron: Myelin sheaths are insulating layers around the axon of a neuron, formed by glial cells (Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system). They allow for faster conduction of action potentials through a process called saltatory conduction.
Recognize the impact of multiple sclerosis (MS) on neurons: MS is an autoimmune disease where the immune system attacks the myelin sheaths, leading to their damage or destruction. This demyelination disrupts the efficient conduction of action potentials along the axon.
Compare the conduction of action potentials in typical neurons versus neurons affected by MS: In typical neurons, the myelin sheaths enable rapid transmission of electrical signals. In neurons affected by MS, the damaged myelin sheaths slow down or block the conduction of action potentials.
Evaluate the provided options: The first option is incorrect because typical neurons do have voltage-gated sodium channels along the axon, which are essential for action potential generation and propagation. The second option is irrelevant because the number of dendrites is not directly related to MS. The fourth option is incorrect because MS does not directly increase neurotransmitter release at synapses.
Identify the correct answer: The correct answer is that neurons affected by MS have damaged myelin sheaths, leading to slower action potential conduction. This aligns with the known effects of MS on neuronal function.
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