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Nerves carry messages from your toes to your brain. How does a signal travel along a nerve?
Neuron Signals lab · Last updated: 16 October 2026
Nerves carry messages from your toes to your brain in a split second. In this 3D lab, you follow a signal as it races along a nerve cell and jumps the gap to the next one. It explains reflexes, why we feel pain so quickly and how the brain talks to the body.
What you'll discover
- A nerve signal is a wave of electrical change that travels along the nerve cell's long fibre.
- A fatty coating on many nerve fibres makes signals jump along much faster.
- At the gap between nerve cells, the signal is passed on by chemical messengers.
The science in plain words
Nerve cells, or neurons, carry information around the body. Each has branching dendrites that receive signals, a cell body and a long thin fibre called an axon that carries the signal onwards, sometimes for close to a metre, from the base of the spine to the toes.
At rest, the inside of a neuron is slightly negative compared with the outside, because of the way charged particles called ions are spread across its membrane. When a neuron is stimulated strongly enough, tiny gates in the membrane open and sodium ions rush in, briefly making the inside positive. This change triggers the next patch of membrane to do the same, so a wave of electrical change, called an action potential, sweeps along the axon. Potassium ions then flow out to reset each patch, ready for the next signal.
Many axons are wrapped in a fatty insulating layer called myelin, with small gaps along it. The signal leaps from gap to gap, which makes it far faster than in uncoated fibres. When the signal reaches the end of the axon, it cannot cross the tiny gap to the next cell, called a synapse, electrically. Instead the axon releases chemical messengers, which drift across and trigger a new signal in the next neuron, muscle or gland.
Where it fits
- India, NCERT: Class 10 science, Chapter 6: Control and Coordination
- United States: Grades 6 to 12
- Next Generation Science Standards: MS-LS1-8
Common questions
How fast do nerve signals travel?
It depends on the nerve. Signals in thin, uncoated fibres crawl along at around a metre per second, while those in thick fibres wrapped in myelin can travel over 100 metres per second. That is why you jerk your hand from a hot pan before you even feel the pain fully.
What is a synapse?
A synapse is the tiny gap where one nerve cell meets the next cell. The electrical signal cannot jump across, so the first cell releases chemical messengers that cross the gap and start a new signal on the other side. Synapses let signals be passed on, strengthened or blocked.
What is a reflex action?
A reflex is a fast, automatic response, such as pulling your hand away from something hot. The signal travels to the spinal cord, which sends a command straight back to the muscles without waiting for the brain to decide. This saves precious time.
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Try it yourself
The Neuron Signals lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.