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The Action Potential | Myelinated Axons

Action potentials are exciting all-or-nothing events in neurons, where a membrane depolarization becomes self-reinforcing and quickly travels down the length of axons. Action potentials are neurons' solutions to passing electrical messages reliably, without fail. This video introduces how voltage-gated ion channels and their positive- and negative-feedback loops explains the characteristic shape of action potentials. They are described quantitatively by the Hodgkin-Huxley equations. Neurons have a need for speed, and it turns out that even action potentials do not travel quickly enough down long axons when a very fast response is necessary. The second half of this video derives two different solutions from the Cable Equations to speed up action potential propagation: giant axons (if you're a squid) or myelinated axons (if you're human, and you probably are). Playlist for all videos in series:    • Introduction to Neuroscience   Professor Bing Wen Brunton www.bingbrunton.com @bingbrunton on twitter %%% CHAPTERS %%% 0:00 Passing messages without failure 3:20 Voltage-gated ion channels 6:20 Steps of an action potential 12:43 Key concepts for action potential 16:30 Hodgkin & Huxley 26:35 When voltage-gated channels go wrong! 32:48 Action potential travel IN SPACE 37:45 Myelinated axons are fast 48:25 When myelination goes wrong! 50:37 Key concepts and summary