Action Potentials Are Propagated in a One-Way Direction Down a Neuronal

Multiple Choice

Action potentials are propagated in a one-way direction down a neuronal plasma membrane because

A) the action potential is of insufficient intensity to stimulate the voltage-gated ion channels behind it
B) the adjacent channels upstream from the action potential are ligand-gated
C) the adjacent channels upstream from the action potential are in a refractory period
D) voltage-gated ion channels are suppressed
E) the adjacent channels upstream from the action potential are at their threshold potential