Neuronal Signaling through Action Potentials

The passive current across the membrane caused by a synaptic or receptor stimulation does not travel far because the depolarization declines with distance, due to the leakage through the transmembrane ion channels. However, if this initial depolarization is strong enough to pass the threshold, an action potential will be triggered (usually initiated at the interface between the cell body and axon) and the inward Na⁺ currents produce more passive currents, which travel down the axon to depolarize new pieces of membrane to continue the process. The sequentially triggered action potentials relay the neuronal signal from the synapse or the receptor along the axon to its terminators, where the signal is passed on to other neurons.