Madeline from the US emailed in asking all about nerves, so we
thought we'd help her out. Here you are Madeline, a post just for
you - and anyone else who's interested in the human body.
What are nerves?
Nerves are cells called neurones, which make up our
nervous system. Nerves are specialised cells -
they carry messages from one part of the body to another, as tiny
electrical signals. These messages are also known as nerve
impulses. Do you want to run? Your nerves will tell your leg
muscles to move.

Nerve cells carry messages from
one part of the body to another
There are three different types of neurones, each with a
slightly different function.
- Sensory neurones carry signals from sensory
receptors to the spinal cord and brain. Together, the spinal cord
and brain make up the central nervous system.
Sensory receptors are specialised cells. They detect changes in the
environment, called stimuli, and turn them into
electrical impulses. Sensory neurones carry these electrical
impulses to the spinal cord and brain. Receptors are located in
organs such as the ear, eye and skin. Each organ has receptors
sensitive to particular kinds of stimulus e.g. sound, movement,
touch.
- Relay neurones carry messages from one part of
the central nervous system to another.
- Motor neurones carry signals from the central
nervous system to an effector - a part of the body that produces
the response to the signal. Effectors include muscles and
glands.
Did you know?
- Nerves are the oldest and longest cells in the body!
- The neuron from your spinal cord to your big toe can be up to 1
metre long!
Have a look at our "How sensitive are you?" experiment to find
out more about receptor cells.
This interactive picture tells you a bit more about nerves:
I'm sorry, it appears you do not have flash installed.