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.

Action potentials move more slowly along the axon

Explanation:

Generally    a myelinated neuron is made up of gaps or nodes, which  have sodium gated channels. These gaps made action potential to jump from one intemetient nodes to another in a saltatory conduction. Therefore as action potential moves along the axon membranes, on reaching the nodes they jump.This increases the speed of conduction and transmission  of action potential.

Due to de-myelination in MS, action potential are still generated.However, because the nodes are no longer present, saltatory conduction  does  not occur,therefore transmission is very slow. Hence motor control is lost by the subject.

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