How neurons communicate using electricity and chemistry
The human brain is often compared to a supercomputer, but instead of wires and circuits, it relies on billions of tiny cells called neurons. These neurons allow you to think, move, feel emotions, and even read this article.
So how do neurons “talk” to each other?
The answer lies in a fascinating combination of electricity and chemistry. Neurons use electrical signals to send messages quickly along their length, and chemical signals to pass messages between cells. This electrochemical communication is the foundation of the nervous system.
What Is a Neuron?
A neuron is a specialized cell designed to transmit information. It has three main parts:
Dendrites: Branch-like structures that receive signals
Cell body (soma): Processes incoming signals
Axon: A long fiber that sends signals away from the cell
At the end of the axon is a tiny gap called a synapse, where communication with the next neuron occurs.
The Electrical Side: Action Potentials
Neurons communicate electrically through signals called action potentials. These are rapid changes in electrical charge that travel along the axon.
Resting Potential
When a neuron is not sending a signal, it has a resting potential of about –70 millivolts (mV). This means the inside of the neuron is more negatively charged than the outside.
This charge difference exists because of uneven concentrations of ions:
Sodium ions (Na⁺) are more concentrated outside the neuron
Potassium ions (K⁺) are more concentrated inside
The neuron’s membrane controls the movement of these ions using ion channels and pumps.
Generating an Action Potential
When a neuron receives a strong enough signal, sodium channels open. Sodium ions rush into the cell, making the inside more positive. This sudden change is called depolarization. If the membrane potential reaches about –55 mV, an action potential is triggered. The electrical signal then travels down the axon like a wave.
Afterward:
Sodium channels close
Potassium channels open
Potassium ions flow out, restoring the negative charge (repolarization)
This process happens in just a few milliseconds.
The Chemical Side: Synaptic Transmission
Electrical signals cannot jump across the synapse. Instead, neurons use chemistry to pass the message.
What Happens at the Synapse?
The action potential reaches the end of the axon
Calcium ions (Ca²⁺) enter the neuron
This causes vesicles filled with chemicals called neurotransmitters to release their contents into the synapse
Neurotransmitters diffuse across the synaptic gap and bind to receptors on the next neuron.
Common Neurotransmitters
Different neurotransmitters have different effects:
Glutamate: Excites neurons (most common neurotransmitter)
GABA: Inhibits neurons, preventing overactivity
Dopamine: Involved in reward, motivation, and movement
Serotonin: Affects mood, sleep, and appetite
Acetylcholine: Important for muscle movement and memory
Each neurotransmitter has a specific shape that fits only certain receptors, like a key fitting into a lock.
Turning Chemistry Back Into Electricity
When neurotransmitters bind to receptors, they cause ion channels to open or close. This changes the electrical charge of the receiving neuron.
If sodium ions enter, the neuron becomes more positive (excitation)
If chloride ions enter or potassium leaves, the neuron becomes more negative (inhibition)
If enough excitation occurs, the next neuron fires its own action potential, and the message continues.
Why Use Both Electricity and Chemistry?
Using both systems gives neurons important advantages:
Electric signals are fast and efficient for long distances
Chemical signals allow control, flexibility, and amplification
Chemistry also allows many drugs and medicines to work. For example:
Antidepressants affect serotonin levels
Anesthetics block neurotransmitter action
Caffeine blocks adenosine receptors, increasing alertness
When Communication Goes Wrong
Problems in electrochemical signaling can lead to disorders:
Epilepsy: Too much excitation in neurons
Parkinson’s disease: Loss of dopamine-producing neurons
Depression: Imbalances in neurotransmitters like serotonin
Understanding neuron communication helps scientists develop better treatments for these conditions.
In Conclusion
Neurons communicate using a remarkable blend of electricity and chemistry. Electrical signals carry information rapidly along neurons, while chemical signals allow messages to cross tiny gaps and be carefully controlled.
This electrochemical system powers every thought, movement, and emotion you experience. Though each signal is small, together they form the complex network that makes the human brain one of the most extraordinary systems in nature.
