The Nervous System

Your nervous system is your body's communication network. It sends and receives signals at remarkable speed to control every movement, sensation, thought, and reflex. It has two main parts: the central nervous system, made up of the brain and spinal cord, and the peripheral nervous system, which is all the nerves branching out to the rest of your body.

Think of the brain as the head office and the spinal cord as the main motorway running down your back. Nerves are the roads that branch off this motorway to reach your fingers, toes and everywhere in between, carrying messages in both directions all the time.

The basic building block of the nervous system is the neurone, a special cell shaped for sending signals. Each neurone has a cell body, branching arms called dendrites that receive messages, and a long thread called an axon that carries the message onwards to the next cell.

Neurones do not quite touch each other. Between them is a tiny gap called a synapse. To pass a message across the gap, the neurone releases tiny chemicals called neurotransmitters, which float across and pass the signal on. Billions of these handovers happen every second inside you.

The peripheral nervous system has two parts. The somatic nervous system handles voluntary actions — movements you choose to make, like kicking a ball. The autonomic nervous system controls things you do not think about, such as your heartbeat, breathing and digestion, working away quietly in the background.

One job of the autonomic system is the fight-or-flight response. When your brain senses danger, a chemical called adrenaline is released, your heart speeds up, and your muscles get extra blood, all in a fraction of a second. This is your body getting ready to act quickly to keep you safe.

Your nervous system also lets you learn and remember. Every time you practise a skill, like riding a bike or playing a tune, the neurones involved build stronger connections. That is why something tricky at first slowly becomes easy — your nervous system is rewiring itself to help you.