Sodium/Potassium
Local ionic currents
pump uses ATP to
Na+ channels close
cause resting
pump ions by
potential to rise
active transport
Membrane
depolarises to
+40mV
K+ diffuses out of
the axon
Na+ diffuses into
axon
All Na+ are open
Sodium ions
pumped out of
axon
K+ channels open
Resting potential
of -70mV achieved
Membrane
repolarises
Potassium ions
pumped into axon
Threshold
potential achieved
Membrane potential
falls to -80mV and
becomes
Hyperpolarised
Voltage gated Na+
channels begin to
open
Action potential propagation
Time /ms
Sodium ions
pumped out of
axon
Resting potential
re-established
Potassium ions
pumped into axon
K+ channels close
Sodium/Potassium
pump uses ATP to
pump ions by
active transport
Potential
Difference /mV