In Which of the Following Would the Rate of Impulse

Question

In which of the following would the rate of impulse conduction be the greatest?
A) a myelinated fiber of 10-µm diameter
B) a nonmyelinated fiber of 20-µm diameter
C) a myelinated fiber of 1-µm diameter
D) a nonmyelinated fiber of 10-µm diameter
E) It would be the same in all because of the all-or-none principle.

Accepted Answer

Myelination speeds up the rate of impulse conduction by allowing the action potential to jump from one node of Ranvier to another, a process called saltatory conduction. Additionally, smaller fibers have higher resistance, which further slows down impulse conduction. Therefore, a myelinated fiber of 10-µm diameter would have the highest rate of impulse conduction.