What's in a nerve?

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.

1. 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.
2. Relay neurones carry messages from one part of the central nervous system to another.
3. 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: