Sensory Nerve Fibers-CNS

Autoimmune diseases such as multiple sclerosis causes neurological

impairment by affecting axon conduction velocity. Which of the following

would slow axonal signal propagation to the greatest extent?

• Increasing axon diameter

• Increasing myelin thickness

• Decreasing leak-channel density

• Decreasing depolarization rate

An 83-year-old man with myasthenia gravis is unable to eat foods such as

steak because of bulbar muscle fatigue. Studies of the man’s bulbar muscles

during contraction might have revealed which of the following compared

with normal?

• Decreased –motor neuron activity

• Decreased –motor neuron activity

• Decreased Ia sensory afferent activity

• Decreased Ib sensory afferent activity

A distracted cook picks up and immediately drops a metal spatula that had

become painfully hot to the touch. Which of the following statements best

describes such reflexes?

• They are mediated by local spinal circuits

• Pain stimuli are transduced by Ruffini endings

• Pain stimuli are transmitted via –motor neurons

• They would be unaffected by demyelination

Forced rapid breathing results in alkalization of the blood which would

lead to which of the following changes in neuronal activity?

• Decrease in neuronal activity

• Increase in neuronal activity

• Initial decrease followed by an increase

• No change in neuronal activity

Which of the following is best described as an elongated, encapsulated

receptor found in the dermal pegs of glabrous skin and is especially abundant

on lips and fingertips?

• Merkel’s disc

• Free nerve endings

• Meissner’s corpuscle

• Ruffini’s endings