Myelin Sheath - GCSE Biology Definition

The myelin sheath is a protective fatty layer that wraps around the axons of neurones, like insulation around electrical wires. It helps to speed up the electrical impulses that travel along neurones, allowing the body to respond quickly to stimuli. This is important for actions such as moving muscles or sensing the environment. Myelin also prevents the signals from leaking out as they pass along the axon. If the myelin sheath is damaged, the impulses can slow down or stop, which can affect how the body functions.