008 The All-or-None Action Potential

008 The All-or-None Action Potential

Ever wondered why people refer to the action potential as “all-or-none”?

Well, I guess you’ll just have to watch the video above to understand. In this video, I use the kitchen sink, a paper towel and marbles to bring the concept home.

If you have any questions/comments, feel free to leave it in the comments field below.

– Leslie Samuel

Transcript of Today’s Video

Hey, this is Leslie Samuel again and I’m kind of excited today. I just posted a poll on my blog, and it was for you guys to help me to decide what the subtitle or slogan for Interactive Biology will be, and the one that you guys decided on was “Making biology fun.” So this is the first time I get to use this introduction. Are you ready for it?

Hello and welcome to Interactive Biology TV, where we’re making biology fun! I like the ring of that. I wasn’t going for that title before, but when you guys suggested it, when you guys voted on it, it really started getting me excited.

Anyhow, in today’s episode, we’re going to be talking about the all-or-none nature of the action potential. We’ve been talking about the nervous system, and depending on which book you read, it might say “all-or-none” or “all-or-nothing.” Either way, we’re talking about the same thing. Now, there are two terms that I want you to know for this episode. The first one is the axon hillock, and the second would be the threshold, okay? We’re in my kitchen today, and I’m going to be using a high-tech device to illustrate these concepts. So, let’s look at what we have here today.

Alright, so this is my high-tech device for today. I’m not going to be doing any dishes even though we’re by the sink, but hopefully, this will get you guys to understand the concept of the all-or-none nature of the action potential. So the two terms I said were the axon hillock and the threshold. Axon hillock is the place where the axon starts. We looked at the neuron and the parts of the neuron, and right where it goes from the soma to the axon, we have the axon hillock. That’s the first place we see voltage-gated ion channels. In a previous episode, I spoke about the proteins in the membrane, and you can go back to that and see what these voltage-gated ion channels do.

But anyhow, this is where action potentials can start. However, in order for them to start, the stimulation needs to be enough to bring it to the threshold. So this, we’re going to imagine that this is my axon hillock, and in order for an action potential to happen, this needs to break, and when this breaks, voltage-gated channels open and ions rush in, and we have that electrical signal.

So, these are my ions, the little blue marbles, and I’m going to put the first one on here and nothing happens, that’s not enough to cause an action potential. I’ll put the second one and nothing happens. This is a pretty strong piece of paper towel. It’s Brawny, and I think that’s the one where you see a really strong man on the plastic wrap, so that should say something about the strength, I think.

Anyhow, I’m going to continue putting, still no action potential. It has not reached threshold just yet, so I’m just going to continue putting these ions. I’m trying to bring it to threshold, but it’s not there as yet. And we’re going to put some more. Evidently, Brawny is pretty strong. No insult against Bounty or any of those other paper towels. But here we go, I’m going to continue putting more stimulation, more stimulation, nothing happens. It’s pretty strong, so let’s dump some more on there. At a certain point, it’s going to reach a point where…

Oh! There we go . . . it breaks and those ions get through. That point was the threshold. Now, up until that point, nothing happened. But once we reached that point, we reached the threshold, it’s enough stimulus to cause the action potential to happen. That is why we call it all-or-none.

So there you have it, it’s all-or-none. It’s either going to happen or it’s not going to happen. If there’s enough stimulation to reach the threshold, as you saw with this elaborate set-up, if there’s enough stimulation, it will cause an action potential. If there isn’t enough, it will not cause an action potential. That’s why we call it all-or-nothing, all-or-none. I hope you enjoyed this episode. If you have any questions or comments, leave them in the comments field below. I’d be happy to answer your questions. Who knows, I might even make a video to answer your specific question. That’s it for this video, and I’ll see you in the next one.

178 comments
collins
collins

Thanks Leslie. You are a blessing. Keep doing to the good work

Nadinakin
Nadinakin

I got a question regarding the voltage threshold. Does a stimulus bring ions? Otherwise, where do the sodium ions that cause a rise in the voltage (to reach the certain threshold) come from? ?

Quamy Burrdy
Quamy Burrdy

just sweet! nice illustration man i wasnt getting it but now i do

dee
dee

thank you

Nikhil Thomas
Nikhil Thomas

Yo yo... Awesome clip clip. My close friend was once a flabby. He went from 284lbs of pure fat into 217lbs of genuine muscle. I couldn't believe it! I just joined personally coz I'm working to get stronger muscles. He made use of the Muscle Building Bible (Look in Google)...

Ghosty Coman
Ghosty Coman

Your home is gorgeous, by the by. Mine looks nowhere near so neat, even the corners that you probably didn't expect to get videotaped, haha.

lilyellaboneshawty
lilyellaboneshawty

this helped me a lot. i like how u use different settings and props in ur videos to teach the lesson!

Ali Stratton
Ali Stratton

Hahaha! I love your paper towel jokes! Thanks so much for posting fun, interesting, and easy to understand videos! They are absolutely wonderful! God bless!!!

kingq katl
kingq katl

MAN THIS GUYS TEETH R SO FUKING WHITE

MCFitnessPT
MCFitnessPT

Who'd thumb this down? Seriously, best description ever, and he's making it fun, good job Leslie!

TheMysthicalWhore
TheMysthicalWhore

Hi I need an answer for question - what is the difference between AP in musle fibre (or nerve fibre) and whole musle (or nerve). I think, in the first case, it is about this law (all or nothing), and in the second case it is about summation of APs of each fiber?? But Im not sure...thank you! Silvia.

philippalexander1994
philippalexander1994

Hey, i am from germany, but never the less i understand your videos pretty well, thank you! :-)

jkmissa
jkmissa

this video is awesome. I laughed so hard when you talked about the big strong brawny man. You really do make biology fun!

hristo hristov
hristo hristov

Hey guys. Nice film. My older brother had been obese. He went from 283 lbs of fat into 200 lbs of purely natural muscle mass. I used to be shocked. I just subscribed personally as I must greatly improve my overall physique. He used the Muscle Building Bible (Search on Google)...

AYYYkay47
AYYYkay47

you are great!! love the videos!

Carvo Loco
Carvo Loco

What do you mean? Biology is fun already!

Rachel Hickey
Rachel Hickey

can you explain how the ion channels open/close and why..with the Na and K..?

tsizemore1982
tsizemore1982

Again. Another awesome video. If only my Adv. A+P class was as interesting as your videos. =)

googke101
googke101

Is that a Southern Adventist University water bottle by the sink? Mind = Blown I go to Union College, another Adventist college in Nebraska. Thanks for your videos!

Hyperiontje
Hyperiontje

Hats off to you for answering every question out there. All your videos are very well structured and easy to understand difficult concepts. Big up!

Barbi32105
Barbi32105

you are a very good teacher.. i like the method you use to teach.. i am going to take microbiology next semester i hope i can find more videos that can help me get a good grade =)

RainbowxxMartini
RainbowxxMartini

Thank you so much for picking up the slack of my bio teacher. He is so lazy and condescending. I'm so happy that I stumbled upon your videos! You are definitely helping my mark :)

missrej123
missrej123

Im learning a lot from your vids Sir. Im a nursing student and I stopped for a year, and Im refreshing my mind from the things that arent clear from me before. now I fully understand these things now:))) I will prepare myself from passing board exam;)

yasminhabibty
yasminhabibty

Amazing, and I really mean it. Thanks a lot. I was moved by the creativity of this episode. Just like you hoped that we enjoyed this show. I thoroughly enjoyed it.

tommysmommy2
tommysmommy2

LOVE your videos--show them to my psych class often. Thank you.

blueBruSea
blueBruSea

Your video is amazing. What's amazing is that a concept I had to reread multiple times was answered just by watching your video once. Great job with all the videos so far. They're fun, interactive, easy to grasp, and concise. Thank you :D

reality237
reality237

lol paper towel jokes are hilarious real helpful video though!!!!

ethan forrest
ethan forrest

is there a video on how nerve signals travel?

stikkle55
stikkle55

is action potential the same as the electrical pulse?

SaraSiraj
SaraSiraj

Thank you very much, I read my text book many times & couldn't clearly understand the concept until I watched your video. Keep the amazing work & God bless you!

Lisa Ledwidge
Lisa Ledwidge

Could you add in a note to the video on what you mean when you say "stimulus"? Thanks. Your videos are helpful! I like that they are short. I'm planning to recommend them to my A&P students.

wendic1
wendic1

Thank you so much for your explanations. They are really helping me understand.

InteractiveBiology
InteractiveBiology

Hi! You'll find Episodes 041 to 043 at Interactive-Biology about muscle contraction. Hope they'll help. Have fun!

InteractiveBiology
InteractiveBiology

Hi! You'll find Episodes 041 to 043 at Interactive-Biology about muscle contraction. Hope they'll help. Have fun!

ai18able
ai18able

Peace be upon you Mr. InteractiveBiology :) can you make a video on mechanism of muscle contraction and relaxation?really hope you can help me. thank you! :)

ai18able
ai18able

Peace be upon you Mr. InteractiveBiology :) can you make a video on mechanism of muscle contraction and relaxation?really hope you can help me. thank you! :)

MHCOCC
MHCOCC

This was a great way to explain this concept-thanks for making this a very visual explanation-now I won't forget the 'all or none' aspect!

MHCOCC
MHCOCC

This was a great way to explain this concept-thanks for making this a very visual explanation-now I won't forget the 'all or none' aspect!

JaredAugerot
JaredAugerot

you should do Google AdSense for brawny or whatever towel you used.

JaredAugerot
JaredAugerot

you should do Google AdSense for brawny or whatever towel you used.

silverlining723
silverlining723

Is the amount of stimulation before threshold is reached the graded potential?

silverlining723
silverlining723

Is the amount of stimulation before threshold is reached the graded potential?