Gated ion channels are selective membrane pores that open or close in response to voltage, neurotransmitters, or mechanical stimuli; Their timing controls membrane potential changes during nervous transmission.
Coverage 2025–2025 · Updated 15 Jul 2026
Gated ion channels are selective pores that open when a specific chemical or voltage signal changes protein conformation; ions then diffuse down their electrochemical gradients.
| Gate type | Stimulus and neuronal example |
|---|---|
| Neurotransmitter-gated | Acetylcholine binds a nicotinic acetylcholine receptor, opening its ion channel at a synapse |
| Voltage-gated | A membrane-potential change opens sodium channels and later potassium channels during an impulse |
The gate determines when the pore is available, pore chemistry determines which ions fit, and the electrochemical gradient determines direction and rate after opening.
After depolarization reaches threshold, voltage-gated sodium channels open and sodium enters down its electrochemical gradient; the channel does not pump sodium.
Opening a channel supplies no energy for uphill transport. Do not confuse the opening stimulus with the force that moves ions through the open pore.
This objective is assessed through structured response, commonly using Explain / State / Identify.
Explain / State / Identify
Build the answer around this relationship: Voltage-gated potassium channels open in response to membrane-potential changes.
Swapping neurotransmitter-gated acetylcholine receptors with voltage-gated potassium channels.
Representative question
Explain the action of the voltage-gated potassium channel during a nerve impulse.
The HL extension asks how membrane structure becomes dynamic cell behaviour. Fatty acid saturation and cholesterol tune fluidity. Fluid membranes form and fuse vesicles. Gated ion channels and sodium-potassium pumps create nerve-cell gradients and electrical responses. Sodium-dependent glucose cotransport uses a sodium gradient to move glucose indirectly against its gradient. Adhesion molecules organize tissues.
