Final answer:
Multiple sclerosis causes slower transmission of action potentials due to axon demyelination. The autoimmune destruction of myelin sheath leads to impaired electrical signal propagation and various neurological symptoms. Demyelination in MS affects saltatory conduction, crucial for quick nerve signal transmission.
Step-by-step explanation:
Multiple sclerosis (MS) results in slower transmission of action potentials in the nervous system by causing A) Axon demyelination. This demyelination happens because of an autoimmune response where the body's immune system mistakenly attacks the myelin sheath that normally insulates nerve fibers and facilitates rapid signaling. As the myelin is damaged, electrical signals leak from the axon, which slows down the action potential conduction. This effect is most evident in conditions like MS, where multiple areas of scarring (sclerosis) and demyelination can be found in the brain and spinal cord, leading to symptoms such as fatigue, muscle weakness, and sensory deficits.
The myelin sheath works as an insulator, and in myelinated axons, it allows the action potential to 'jump' from one node (Ranvier) to the next through a process known as saltatory conduction. When the myelin is compromised, this process becomes inefficient, causing a delay in nerve signal transmission and a variety of neurological symptoms associated with MS.