Question

During action potential propagation in an unmyelinated axon, why doesn't the action potential suddenly "double back" and start propagating in the opposite direction?

Answer 1

The region fo the neuron is in the refractory period as the sodium channels are inactivated.

Step-by-step explanation:

• A propagating action potential always leaves a trail of refractory membrane in its wake.
• The trailing membrane takes some time to recover from the action potential it just experienced.
• This is largely because its voltage-gated sodium channels are inactivated.
• By the time this membrane segment is ready to (re)generate another action potential, the first propagating action potential is long gone.