Every heartbeat begins as an electrical spike inside heart-muscle cells. Watch the distinctive plateau that sets heart muscle apart from nerve.
Cardiac Action PotentialLive
the electrical heartbeat
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Each heartbeat is an electrical wave: a fast sodium upstroke, a long calcium plateau unique to heart cells, then potassium repolarization. That plateau keeps the muscle contracted long enough to pump — and its length sets the refractory period. Educational tool, not medical advice.
Reading this result: The plateau holds the cell near 0 mV for ~343 ms — the calcium phase unique to heart muscle that keeps it contracted long enough to pump before potassium repolarizes it.
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How it works
A cardiac action potential has a fast sodium upstroke, a long calcium plateau, and potassium-driven repolarization. The plateau — absent in nerve cells — keeps the muscle contracted through the whole squeeze and creates a long refractory period that prevents tetanus. Educational tool, not medical advice.
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Is this cardiac action potential simulator tool really free?▾
Yes. Cardiac Action Potential runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
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No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
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The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.