How does demyelination affect nerve impulse transmission?

• A. Increases transmission speed
• B. Has no effect on transmission
• C. Slows down or blocks transmission
• D. Strengthens communication between neurons

Answer: (C)

Demyelination affects nerve impulse transmission by slowing down or blocking the transmission of signals along the affected nerves. Myelin is a fatty substance that surrounds and insulates nerve fibers, allowing electrical impulses to travel rapidly and efficiently between neurons through a mechanism called saltatory conduction. This process occurs where the impulse jumps from one node of Ranvier (gaps in the myelin sheath) to the next, greatly increasing the speed of transmission.

When demyelination occurs, as seen in conditions like multiple sclerosis, the insulating properties of myelin are compromised. This results in a significant decrease in the speed of nerve signal transmission, or in severe cases, can completely block the transmission of impulses. As a result, individuals may experience symptoms such as weakness, numbness, difficulty in coordination, and other neurological deficits.