Medical

The Peripheral Neuropathy Solution

Peripheral Neuropathy Solution By Dr. Randall Labrum

Get Instant Access

Myelin

Schwann Cell Nuclei

Copyright 2000 Gold Standard Multimedia, Inc. All rights reserved.

Figure 1-2-2. Axons Cut in Cross-Section

Myelin

Axons may be unmyelinated or myelinated, depending on the type of covering provided by their supporting cells.

Unmyelinated Axons

Unmyelinated axons in peripheral nerves are surrounded by the cytoplasm of Schwann cells.

• These axons have a small diameter and a relatively slow conduction velocity.

• A single Schwann cell may ensheath several axons.

Myelinated Axons

Myelinated axons are larger in diameter and are ensheathed in myelin (Figure 1-2-2).

Schwann cells are the myelin-forming cells of the peripheral nervous system (PNS). Myelination in the PNS begins during the fourth month of development. One Schwann cell will myelinate only one axon in peripheral nerves.

Oligodendrocytes are the myelin-forming cells of the central nervous system (CNS). In the CNS, myelination begins during the fourth month of development and continues into the second decade of life. An individual oligodendrocyte is able to myelinate many axons.

Node of Ranvier

At the junction between two myelin-producing cells, there is a discontinuity in the myelin. This creates a "collar" of naked axon, called a node of Ranvier, which is exposed to the extracellular space (Figure 1-2-1). The action potential skips from node to node in a process called saltatory conduction. Myelinated axons conduct action potentials rapidly.

Composition

Because myelin is of membrane origin, it is rich in phospholipids and cholesterol.

Clinical Correlate

The degeneration of oligodendrocytes results in many of the so-called demyelinating disorders, such as multiple sclerosis.

Myelin

Schwann Cell Nuclei

Copyright 2000 Gold Standard Multimedia, Inc. All rights reserved.

Figure 1-2-2. Axons Cut in Cross-Section

KAPLAN..

Was this article helpful?

0 0
Peripheral Neuropathy Natural Treatment Options

Peripheral Neuropathy Natural Treatment Options

This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.

Get My Free Ebook


Post a comment