Intro | Axon | Axon Hillock | Dendrites | Myelin Sheath | Nodes of Ranvier | Soma | Synapse | Terminal Buttons
Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
Return to main tutorial page
The gaps (approximately 1 micrometer wide) formed between myelin sheath cells long the axons are called Nodes of Ranvier. Since fat serves as a good insulator, the myelin sheaths speed the rate of transmission of an electrical impulse along the axon. The electrical impulse jumps from one node to the next at a rate as fast as 120 meters/second. This rapid rate of conduction is called saltatory conduction. Myelinated axons are rare in the autonomic nervous system. Invertebrates do not have myelinated sheaths.