Saltatory Conduction and Myelination

Anatomy of Myelination

• Myelin: A lipid substance created by Schwann cells that wraps around axons; it is characteristic of white matter, whereas gray matter axons are unmyelinated.

• Nodes of Ranvier: Gaps in the myelin sheath that contain a large concentration of voltage gated sodium channels.

Saltatory Conduction

• Mechanism: The action potential is generated at the axon hillock and moves down to the Nodes of Ranvier; sodium rushes into the node and depolarizes the axon, acting like a relay boost.

• Saltatory Conduction: The phenomenon where an action potential appears to jump from node to node, resulting in faster transmission in myelinated white matter compared to unmyelinated gray matter.

Clinical Significance of Myelin Loss

• Demyelination: The loss of myelin sheaths reduces the ability of neurons to transmit information.

• Associated Disorders: Includes peripheral neuropathies such as diabetic neuropathy, carpal tunnel syndrome, and neuropathy of pregnancy.

• Symptoms: Loss of sensation, motor function, and reflexes.