What is the myelin sheath?

The myelin sheath is a layer of insulating, fatty material that encases some neurones. The sheath is composed of Schwann cells that have gaps called nodes of Ranvier between them. Potassium and sodium ions can only diffuse in and out of the neurone at these gaps. This allows saltatory or 'jumping' conduction where the local currents are elongated as the sodium ions have to diffuse further along the neurone before the action potential can occur. The action potential appears to 'jump' from one node of Ranvier to another.

AH
Answered by Alice H. Biology tutor

4461 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Explain the cell cycle


Describe the synaptic transmission of a nerve impulse at the neuromuscular junction


What is the basic biochemistry of carbohydrates?


Many enzymes present in cells require a catalyst to aid their actions. Describe the role of a catalyst.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning