In multiple sclerosis, the myelin sheaths around the axons of the brain and spinal cord are damaged and demyelination results. How does this disease manifest at the level of the action potential?
I.Action potentials move in the opposite direction on the axon.
II.Action potentials move more slowly along the axon.
III.No action potentials are transmitted.
A) only I
B) only II
C) only III
D) only II and III

Question

Quizplus · Accepted Answer

The demyelination of the myelin sheath leads to a slower propagation of action potentials along the axon. Option A is incorrect because the direction of propagation of the action potential is not affected. Option C is incorrect because there may still be some transmission of action potentials even though it may be limited or disrupted.

In Multiple Sclerosis, the Myelin Sheaths Around the Axons of the Brain