The Children's Hospital Boston has an instructive interactive diagram explaining some of the electrical and chemical processes in the neuron. Although it probably goes into slightly less detail, quite frankly it does a solid job of summarizing the information I learned about neurons in my physiological psychology class this semester.
It is strange, then, that it is advertised as "for children." What kind of children are they talking about? I didn't see any references to Digimon. This reminds me of Eliezer Yudkowsky's post about when he tried to explain Bayesian inference at the elementary school level. It ended up being wildly successful for college-level students. I have two conclusions:
1) Don't allow hubris to prevent you from reading things aimed for a lower level than you consider yourself. It will be easier to read and it will help you ground yourself on the basics.
2) If you are explaining something, it might be helpful to pretend that you are explaining it to somebody at a much lower technical level than you really are. You shouldn't admit it, of course (to avoid problem #1 altogether), but it will help the actual understanding of your readers tremendously.
Of course, this all assumes that you know what you're talking about. If you don't, you should probably go ahead and use as much technical jargon and as many acronyms as possible.
Link to the diagram of the neuron. (Hat tip: Mind Hacks)