Introduction

Let’s delve into the basics of nervous transmission by looking at a motor neurone. Here is the structure of a myelinated motor neurone:

Labelled “insulating sheath”, the myelin sheath is responsible for protecting the electrical impulses that run across the neurone.

Dendrites carry electric signals i.e. nerve impulses towards the cell body (the soma), while the axon carries them away, often towards the receiving dendrites of other neurons.

The Myelin Sheath

This insulating sheath made up of Schwann cells is key in ensuring fast signal transmission. The signal is able to “jump” along the axon without losing its strength. Instead of the signal being gradually weakened by the resistance that an axon membrane exposed to the environment creates, this signal is shielded by the…