What is action potential Find an outside source that aids in the explanation of the 6 steps involved with action

What is action potential?
Find an outside source that aids in the explanation of the 6 steps involved with action potential and the sensation of stimuli.
1. Explain what action potential is and how it is involved with sensation (of anything!).
2. Explain what action potential is. (Summarize the 6 stages of an action potential event).
3. Explain how a spider can climb up your arm but you dont feel it the entire time?!
4. Site your sources.