Chapter 12.4, Problem 9AYLO

Summary Introduction

To discuss:

Saltatory conduction in myelinated nerve fiber, difference in conduction mechanism of nodes of Ranvier and internodes, and why signal travels faster in myelinated nerve fibers than unmyelinated fibers.

Introduction:

The nerve fiber is insulated by a spiral layer called myelin, which is produced in both CNS and PNS. The formation of myelin is called myelination or myelinogenesis. Schwann cells spiral a single nerve fiber repeatedly forming hundred compact layers without cytoplasm between the plasma membrane. These layers form the myelin sheath. This myelin sheath is absent in unmyelinated nerve cells. The myelinated cells conduct signals in a distinct manner known as saltatory conduction; saltatory means “jumping” or “leaping”. These myelinated fibers are unable to conduct the signal continuously.