Action Potential Oscilloscope
Drag the timeline to see exactly how voltage changes correspond to the opening and closing of voltage-gated ion channels during a neural impulse.
About this simulation
- What
- An interactive Biology simulation of Action Potential Oscilloscope.
- Who
- Designed for AP, IB, and A‑Level Biology students.
- How
- Runs in any modern browser — drag, adjust, and explore in real time.
Updated 2026-04-10
Key Concepts
Depolarization
Na⁺ channels open, allowing Na⁺ to rush into the cell, shifting the voltage from -70mV up to +30mV.
Repolarization
Na⁺ channels inactivate, K⁺ channels open, and K⁺ rushes out, returning voltage to negative.
Refractory Period
The period where channels reset. The Na⁺/K⁺ pump continuously works to restore the original concentration gradients.
Understanding the Action Potential
An action potential is a rapid sequence of changes in the voltage across a membrane. It allows neurons to transmit signals over long distances.
The entire process strictly follows an 'all-or-none' law: if the stimulus does not reach the threshold (around -55mV), no action potential occurs. But once triggered, the amplitude of the spike is always the same.
Remember that the oscilloscope trace is just a macroscopic readout of microscopic events: the opening and closing of voltage-gated ion channels.