sentence: Insulation is provided by specialized cells called myelin that wrap around the axon.
sentences_before: The electrical signal of an axon is made by ions that flow in and out of the cell in a chain reaction called an action potential. The speed at which the signal travels depends on how thick the axon is, and how much insulation it has.
concept_name: insulation
headings: Axon
categories: Anatomy of the nervous system