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: [ Ссылка ]
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
![](https://i.ytimg.com/vi/YcM7dUnp2cI/maxresdefault.jpg)