Question

In multiple sclerosis, slow conduction of motor and the sensory pathways is due to?

• A. Defect in the node of Ranvier
• B. Loss of myelin sheath
• C. Leaking of sodium channels
• D. Leaking calcium channels

Answer 1

The Correct Option is B

In multiple sclerosis (MS), the primary factor contributing to the slow conduction of motor and sensory pathways is the loss of the myelin sheath. To understand this, it's important to grasp the role of myelin in the nervous system:

• Myelin Function: Myelin is a fatty substance that wraps around the axons of neurons in the central and peripheral nervous systems. This insulating layer is crucial for the rapid transmission of electrical signals along the nerve fibers.
• Saltatory Conduction: In myelinated neurons, electrical impulses hop from one node of Ranvier (gaps in the myelin sheath) to the next. This process, known as saltatory conduction, allows for much faster signal transmission compared to unmyelinated fibers.
• Impact of Myelin Loss: In MS, the immune system mistakenly attacks and damages the myelin sheath. This demyelination disrupts saltatory conduction, slowing down or even blocking nerve signal transmission. As a result, it leads to the neurological symptoms observed in MS patients, including impairments in movement, sensation, and coordination.

Given these points, it's clear that the loss of the myelin sheath is the reason for the slow conduction of motor and sensory pathways in multiple sclerosis.