PhysSandbox
Classical MechanicsWaves & SoundElectricity & MagnetismOptics & LightGravity & OrbitsLabs
🌙Astronomy & The Sky🌡️Thermodynamics🌍Biophysics, Fluids & Geoscience📐Math Visualization🔧Engineering🧪Chemistry

Related simulators

Continue with similar topics in this category — or all 44 in Biophysics, Fluids & Geoscience.

View category →
NewUniversity / research

Cardiac Action Potential

Launch Simulator

FitzHugh–Nagumo/Noble-style cardiac toy: fast upstroke, plateau-like repolarization, refractory recovery gate, and S1-S2 premature-stimulus capture vs block.

NewSchool

Nernst Potentials & Membrane

Launch Simulator

Nernst E for K⁺ and Na⁺ from inside/outside concentrations; optional Goldman–Hodgkin–Katz resting estimate.

NewUniversity / research

Calcium Waves / IP3 Oscillator

Launch Simulator

Li-Rinzel-style IP3 receptor oscillator: cytosolic Ca, ER store, calcium-induced calcium release, SERCA refilling, flux traces, and a Ca–h phase portrait.

NewUniversity / research

Hodgkin-Huxley / FHN Neuron Network

Launch Simulator

Multi-node excitable network using FHN reductions of HH dynamics: chain/ring topology, sigmoidal synaptic coupling, propagation delay, pacer-driven waves, and bursting-like activity.

NewUniversity / research

Cable Equation on an Axon

Launch Simulator

1D passive cable ∂V/∂t = D∂²V/∂x² − (V−V_r)/τ + I; compare uniform fiber vs myelinated (higher D in internodes).

NewSchool

Coupled FitzHugh–Nagumo Neurons

Launch Simulator

Two excitable FHN units with diffusive coupling: phase plots, time traces, and synchronization vs coupling strength.

PhysSandbox

Interactive physics, chemistry, and engineering simulators for students, teachers, and curious minds.

Physics

  • Classical Mechanics
  • Waves & Sound
  • Electricity & Magnetism

Science

  • Optics & Light
  • Gravity & Orbits
  • Astronomy & The Sky

More

  • Thermodynamics
  • Biophysics, Fluids & Geoscience
  • Math Visualization
  • Engineering
  • Chemistry

© 2026 PhysSandbox. Free interactive science simulators.

PrivacyTermsContact
Home/Biophysics, Fluids & Geoscience/Hodgkin–Huxley Action Potential

Hodgkin–Huxley Action Potential

Squid-axon HH ODEs: membrane voltage V(t) and gating (m, h, n); step stimulus and Na⁺/K⁺ conductance traces.

Stimulus

12 µA/cm²
2 ms
40 ms

Classical Hodgkin–Huxley (squid giant axon parameters): C dV/dt = I − g_Na m³h(V−E_Na) − g_K n⁴(V−E_K) − g_L(V−E_L), with α/β kinetics for m,h,n. A depolarizing current pulse from t = 1 ms can trigger an action potential if above threshold.

Measured values

Peak V40.5 mV

RK4 on the HH ODEs; pulse starts at 1 ms. Increase I or pulse width to cross threshold and fire.

Live graphs

About this model

The Hodgkin–Huxley model describes excitable biological membranes with voltage-dependent sodium and potassium conductances controlled by gating variables (m, h, n). A depolarizing current raises V; once sodium channels open, positive feedback drives the upstroke, after which potassium repolarizes the cell. This page integrates the classical squid-axon parameter set with RK4 and plots membrane voltage together with effective conductances.

Who it's for: Undergraduates in biophysics or neuroscience learning action potentials beyond integrate-and-fire cartoons.

Key terms

  • Hodgkin–Huxley
  • Action potential
  • Sodium channel
  • Potassium channel
  • Gating
  • RK4

How it works

Numerical integration of the Hodgkin–Huxley excitable membrane: sodium activation/inactivation and potassium activation produce the stereotyped spike; conductance traces show channel gating.

Frequently asked questions

Why two graphs for voltage and conductances?
V spans tens of millivolts while g_Na m³h and g_K n⁴ peak on a different scale; overlaying them on one autoscaling axis would hide one of the traces.