The protein pores and machines in the cell membrane that make neural signalling possible — voltage-gated, ligand-gated and mechanically gated channels, pumps and transporters — and the toxins and drugs that target them.
Neural Signaling
Intermediate
Ion Channels and Pumps
The Editors
February 20, 2026
3 min read
In plain English
Ion channels are tiny protein doors in a neuron's membrane that open to let specific charged particles through. Some open when the voltage changes, some when a chemical binds, some when they're stretched. Pumps work the other way, using energy to move ions uphill. Many toxins and medicines work by blocking these doors.
Intermediate level: Builds on the basics. Introduces the real vocabulary and the mechanisms behind it.
Concepts to know first
Go deeper next
A cell membrane is a thin layer of fat that charged ions can't cross on their own. Ion channels are proteins that form pores through it, letting specific ions flow down their gradients — up to millions of ions per second through a single open channel. Pumps and transporters move ions against their gradients, using energy.
Selective doors
Channels are remarkably selective. A potassium channel lets K⁺ through about ten thousand times more easily than the slightly smaller Na⁺ ion, thanks to a precisely shaped selectivity filter. Roderick MacKinnon's 1998 atomic structure of a potassium channel showed how, and earned him a share of the 2003 Nobel Prize in Chemistry.
What opens them
Voltage-gated channels open or close when the membrane voltage changes. Voltage-gated sodium and potassium channels produce the action potential; voltage-gated calcium channels trigger transmitter release. Ligand-gated channels open when a chemical binds — for example, receptors for glutamate, GABA and acetylcholine. Mechanically gated channels, such as Piezo channels, open when the membrane is stretched or pressed, and underlie touch and hearing. Others respond to temperature (the TRP family, including the capsaicin receptor) or to internal messengers.
Pumps and transporters
The sodium-potassium pump maintains the basic gradients. Calcium pumps keep calcium inside cells extremely low, so that small influxes act as signals. Neurotransmitter transporters pull transmitters back into cells after release — the targets of antidepressants and cocaine.
Toxins, drugs and channelopathies
Nature's poisons often target channels. Tetrodotoxin from pufferfish blocks voltage-gated sodium channels, causing paralysis; local anaesthetics such as lidocaine do something similar more gently, which is why a dental injection numbs your mouth. Many anti-seizure drugs act on sodium or calcium channels. Inherited channel defects — channelopathies — cause some forms of epilepsy, migraine, muscle disorders and cardiac arrhythmias.
Everyday examples & things to try
Analogy
Doors with different locks
Imagine a wall with many doors. Some open when the room's temperature changes (voltage-gated), some need a key (ligand-gated), and some swing open if you lean on them (mechanically gated). Each lets only one kind of guest through. Pumps are bouncers carrying guests back out, one by one, at a cost.
Real world
Why the dentist's injection works
Lidocaine slips into sodium channels in the nerves of your gum and jaw and blocks them. No sodium current, no action potentials — so pain signals never reach your brain, even though the nerve endings are still being stimulated.
Key takeaways
- Ion channels are selective protein pores; pumps use energy to move ions uphill.
- Channels open in response to voltage, chemicals, stretch or temperature.
- Many toxins, anaesthetics and anti-seizure drugs act on channels.
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