How Neurons Send Messages Through Your Body

A neuron has a cell body, branching dendrites and a long fibre called an axon. Dendrites receive signals from nearby cells, while the axon carries a signal away from the cell body. Some axons are wrapped in a fatty covering called myelin, which helps messages travel more quickly and efficiently.

Neurons do not all have the same shape or job. Sensory neurons carry information from sense receptors toward the brain and spinal cord. Motor neurons carry instructions toward muscles and glands. Interneurons connect neurons inside the central nervous system, helping information move through networks rather than along one lonely wire.

The nervous system works because huge numbers of neurons communicate in organised pathways. A single neuron can receive signals from many others, combine that information and then either send its own message or remain quiet. This simple choice, repeated across billions of cells, supports movement, memory, attention and thought.

When a neuron is resting, charged particles are distributed unevenly across its cell membrane. If incoming signals are strong enough, channels in the membrane open and the electrical balance changes. This produces an action potential, a brief electrical event that moves along the axon.

The action potential does not fade like a weak sound travelling down a hallway. Each section of membrane activates the next, so the signal is renewed as it moves. Myelin leaves small gaps along the axon, and the signal appears to jump from gap to gap. This greatly increases speed without requiring the entire membrane to activate at once.

After the signal passes, the membrane returns to its resting condition. For a short time, that section cannot immediately fire again. This recovery helps keep the message moving in one direction and prevents the axon from becoming a confused electrical roundabout.

Neurons usually do not touch. A tiny gap called a synapse separates the end of one neuron from the next cell. When an action potential reaches the axon ending, it triggers the release of chemical messengers called neurotransmitters. Different neurotransmitters can increase, reduce or adjust the next cell's response, allowing nervous pathways to handle far more than simple on-and-off commands.

A useful sequence to remember is:

• •Dendrites receive incoming information.
• •A strong enough signal starts an action potential.
• •The action potential travels along the axon.
• •Neurotransmitters cross the synapse.
• •Receptors on the next cell respond.

Neurons communicate with an electrical signal inside the cell and a chemical signal between cells. Follow the path from dendrites to axon to synapse, and the nervous system becomes a chain of understandable steps rather than a mysterious flash of information.