Comment 5 by Viveca

The action potential is almost what it sounds like (though not quite), as I understand it, also referring to potential difference (i.e. voltage). More importantly, it's the likelihood (potential) of a pulse travelling from one neuron to another it's connected to. The initiation of the pulse is the "action".

The pulses are started off by the action potential getting over a specific threshold, which is the same in all neurons. That has a very wide range of chemical causes, including neurotransmitters, but I think there are more generally present chemicals that don't qualify as such whilst having an influence on neuron operation.

They are not of electrons, but waves of ion presence and absence, with flows in and out of the cell sustained by a combination of electrical and chemical concentration differences between the inside and outside of the neuron, and the activation then timed jamming up of channels that let ions in from outside, along with some other biological machinery (e.g. ion pumps to revert things to their previous state after ions have flowed in to the cell and the channels closed).

I'm not an expert, though, so please do correct any omissions or errors in this summary if you know better. This is intentionally simplified, but I may have missed something critical. Let me know if it's unclear, I'm happy to explain it as well as I understand it.

Oh, and please close your italics tag :)