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 hundreds of 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.

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Chapter 12.4, Problem 17BYGO

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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 hundreds of 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.

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