012 The Absolute and Relative Refractory Periods

[@weirdpride]

That was so well illustrated and explained. This is the exact explanation I needed, thank you!

[@peterkwolek2265]

You are an incredible teacher, thought I was going to be lost at first based on not knowing all the science terms but you explained everything so well.

[@InteractiveBiology]

Thank you very much, Peter. I'm so glad to hear that you're getting value from the videos. Stay tuned (and subscribe) for more.

[@TheAbsoluteTruthzz]

During repolarization Na+ channels close and K+ open causing an efflux of K+ and an overshoot of below -70mV. Sodium potassium pump and leak channels are working in the background to re-establish resting potential.

[@InteractiveBiology]

@jimmyt1222 You are very much welcome. Glad you are finding value in it. Stay tuned because there's much more to come :)

[@warpedoctave]

ive read guyton a couple of times, for hours on end and it finally made sense watching this video, God Bless thanks......... : )

[@MMAFAN21]

Awesome video. I'm a new paramedic and this really a great refresher. Thank you, I'm def subscribing

[@NightWanderer01]

A refractory period simply refers to the time frame in which the generation of further action potentials may be hindered (RRP) or may not occur at all (ARP). Hyperpolarization, in contrast, describes an event where the cell's membrane potential drops to levels below its resting potential due to excess K+ leaving the cell. However, it would be correct to say that hyperpolarization could occur during the RELATIVE refractory period (RRP). Hope that helps!

[@InteractiveBiology]

@katelayt Well, I'm glad I can help. All the best with your class!

[@darkscienceyt]

Superb explanation!

[@InteractiveBiology]

Thanks. Glad to help 👍🏽

[@naghmetalakoub4089]

This helped me a lot I was so confusef. Now every thing makes sense Thank you

[@InteractiveBiology]

@2Aboody Glad we were able to help. Please stay tuned for more Biology learning and fun. We have more Biology videos to be uploaded very soon!

[@chriscrumbley9219]

Thank you so much! I just couldn't wrap my brain around it until I saw this video!

[@alphaWAYNE]

Thank you so much for making these videos... You make biology more fun, easy and very understandable... You are a great teacher. A million thank yous.

[@asseel70iraq99]

Still alive my man?😂😂😂😂😂

[@rhiannonbreezesturgess9870]

So helpful, thank you so much for posting these videos! A&P would be killer without you!

[@xwld2971]

Wow, thank you so much for making this easier! I'm really struggling with psychology. Keep making videos!

[@InteractiveBiology]

You are very much welcome, Carl.

[@shanzahiqbal3517]

Me too

[@redblueweronika]

10 years later, still an awesome video!

[@NaziFaa17]

BEST TEACHER EVER!

[@InteractiveBiology]

@crackowacko87 No, the relative refractory period is longer. It starts at the peak of the action potential and continues until the resting membrane potential is restored. Hope that helps!

[@James-jl6rx]

Clear explanation of what I was confused about! Thank you so much! :D

[@InteractiveBiology]

@warpedoctave Glad to know the videos are helping. Stay tuned for MANY more to come :)

[@ThePhenom94]

MAN THANK YOU! That was so easy and you explained it better than my teacher! ThankYou!

[@bashag5477]

This TOTALLY made sense! Thank you

[@InteractiveBiology]

You're welcome

[@pramvirrathee1751]

5:42 its wrong. Na channels are not closed, but inactivated. You can not use them again until Membrane potential reaches resting potential.

[@004aayushsharma7]

I am very happy to see this video love from 🇮🇳India (my lovely country)

[@InteractiveBiology]

@Djalitana No prob. Glad you found it.

[@mypassioninspiration]

Thank you, Mr. Samuel! You make me confident to get an A for my class! I really appreciate it:]

[@rmaissa4045]

thank you so much ... i study in french but because i didn't understand i try your video and it was so helpful .. thank you

[@InteractiveBiology]

@Matt18a That's what we do at Interactive Biology - Save Lives, lol. Hey, glad to know that you are getting value from it. Make sure to subscribe and stay tuned :)

[@berkayekiz9186]

Thanks alot sir, you've explained it quite simply :)

[@mynameistaken96]

This helped me a lot, thank you!

[@LucifersCounterpart]

the day just smiled at me :D this is the best channel i hav my physiology exam in 2 days n i couldnt understand certain things before finding this channel but as i said grrrrrr8 channel ;D

[@jennifersciberras7484]

You are a FANTASTIC teacher.

[@SaddieMusic]

Thank you so much! I wouldnt change anything in this vid! Keep up the great work!

[@InteractiveBiology]

@adeelfromny Glad you find it helpful. Many more coming, so stay tuned :)

[@jimmyt1222]

Awesome video. Thanks so much for doing this. It would have taken me hours of reading from a textbook to reach this level of understanding. Thank you, thank you, thank you.

[@InteractiveBiology]

@UniGirl9008 Unfortunately, Leslie has a lot of things to do at the moment, getting busy with the site, his work, and personal life. He's not had the time lately to check posts and get back to them. Please do stay tuned though as he'll be uploading more videos soon that may clarify your question. Thank you!

[@onlywei1487]

Thank you so much for helping us crush many difficulties

[@27capricia]

you are great. thanks for putting it in a way that i could get the concepts finally.

[@GlendaPimentelVergeldedios]

Thank YOU, Leslie! God Bless YOU!

[@InteractiveBiology]

@LaSuraya1 Thanks Laura. Glad you like it :D

[@laurelfree18]

Thank you, Thank you, Thank you. So easily explained. Life saver.

[@dibyansukumarpalei8780]

Thanks a lot very helpful after a few days i have my 1st prof mbbs exam

[@doctor.angela]

Thank you so much. It's better than my books' explaination.

[@InteractiveBiology]

@lindaandjeffsampson Thank you :) Glad to know you appreciate this. There are more Biology videos in the website that you might want to check out. Stay tuned for more new videos! :)

[@bananapete]

No, the refractory period and the hyperpolarization are separate events that overlap. This graph could use 2 more variables: % of Na channels open; and % of Na channels inactive. You would see that as the AP starts to spike most of the channels go to open, then around the peak most of the channels go to inactive. The relative refractory period actually starts as the voltage is coming back down from the peak as Na channels transition back to closed and ready.

[@InteractiveBiology]

@TheRobbert1992 You are very much welcome :)

[@redmanhurricanes]

A black guy teaching Bio I love this brotha! Good video, island vibes lol.

[@JesusMartinez-zu3xl]

Thank you!!!! I understood what the periods were but needed a visual aid!!. Thank u!!

[@DavidGreybeard]

This graph might be confusing. The refractory period labelled in the chart is what is called hyperpolarization. I'm not 100% sure but I think the refractory periods are over at that time and the reason why it takes a stronger signal to reach an action potential in a hyperpolarized membrane is because the cell is more negative than normal and takes more sodium ions to reach the threshold. It sounds like the refractory periods have more to do with the voltage gates resetting rather than the charge of the cell.

[@Anne-cc4hn]

yes abt the first remark ! but maybe its not his own graph but for his explaining is convincing

[@InteractiveBiology]

@r3dfreak You're welcome!

[@InteractiveBiology]

@skinnimelon You're welcome. Stay tuned for more!

[@AlexanderGuckenberger]

Thank you sir! This was very helpful, in my opinion! Bless you and thank you sir! :)

[@2Aboody]

thank u for help me to understanding what the different between ARP and RRP

[@inass9713]

Thank you so much. You really saved me 😢❤️

[@7amood3abood77]

best video so far

[@shamamalihashim6159]

YOU ARE A LIFE SAVER. THANK YOU!

[@InteractiveBiology]

@BreatheinStandstill LOL, it's kinda hard to understand gibberish ;) Glad you found value in the videos!

[@malakali537]

we take in our physio coarse that the ARP is from the beginning of action potential to the point that soduim channels get close and this point is at resting before beggining of hyperpolarization part

[@lindaandjeffsampson]

Wow! Great teaching, wish you were my teacher @ school. My teacher goes too fast.

[@fireandice5969]

@UniGirl9008 Refractory period = Repolarization. Hyperpolarization are the K+ ions going further down towards the -90mV range before the pump kicks in to return the Na+ and K+ ions to their resting membrane potential.

[@shrutipathak2096]

Thank you sir From India🇮🇳🙏

[@evii1545]

Thank you so much! I am taking this in class and you were incredibly helpful!

[@nadinesp6141]

Samuel thanks for this video finally understood it!!!

[@InteractiveBiology]

You are very much welcome. That's why we create these videos. Glad to hear it helped. Make sure to share it with others who might also be struggling to understand it.

[@NightWanderer01]

Yes, Na+/ K+ ATPase restores these ion concentrations back to its resting levels.

[@ayatomar9533]

Thank you so much Mr. Samuel

[@InteractiveBiology]

You're very much welcome, Ayat.

[@zahraahmood4040]

The graph looks off. Where it says refractory period, it's suppose to say hyper-polarization. The reason main reason why hyper-polarization happens is because the voltage gated potassium ion channels take a long time to close (and open) which means more potassium is able to flow out of the cell therefore, causing our neuron to become hyperpolarized before it can return to resting membrane potential.

[@hmzas3062]

This video helped me a lot. Thank you very much.

[@InteractiveBiology]

@thamer7A7 You're welcome! Stay tuned for new Biology videos coming very soon!

[@Larethq]

Thanks for the video. It really helped alot in understanding the process

[@charlenem3371]

Thank you so much,I now understand.Keep up the good work!

[@InteractiveBiology]

@yanirmt22 God Bless you too. Glad to know the videos are helping :)

[@ashlu5477]

Thank you, this was so clear and easy to understand!

[@wahid001]

Interactive Biology The Voltage Gated Na+ Channels open after the threshold potential is reached. So if the membrane potential is lower than -55 mV, all Voltage Gated Na+ channels should be closed. The "all or none" response to reach the threshold potential is due to the summation ( Temporal or spatial) of action potentials. which you have already covered in " 019 What is Summation (2 Types)".

[@yashsaxena1217]

@UniGirl9008 Nah, hyperpolarization is a phase not a phase. When the mV drops below -70mV its called hyperploarization, and when it goes back up to -70mV its called polarization. Refractory period is the time it takes for a Na+ channel to open again. This makes sure the action potential moves in one direction.

[@carolinespec]

Great video! Thanks so much!! You made it really easy to understand!

[@johnguillen68]

Thank you for your videos. As I read these chapters its kind of hard to understand what's going on without some kind of picture/video example. But watching your videos and then reading makes more sense.

[@milagroswalker3806]

I finally understand this, thanks a lot.

[@drzainabtahir3554]

Thanks for explaining it so well.

[@Nida003]

Thanks for this good explanation!

[@InteractiveBiology]

You're very much welcome. Make sure to subscribe for more like this.

[@sollehinidris3142]

Hi Leslie, how about Functional Refractory Period?

[@aloovertheworld4948]

Very good job explaining!!

[@InteractiveBiology]

Why thank you

[@imlegend2023]

Thank you so much ! That was very helpful.

[@LSI_MGA]

By "resetting" you mean that the sodium voltage gated ion channels are no longer inactive, but are now deactivated, correct?

[@InteractiveBiology]

@ediniz101 Those questions are answered in Episodes 9 - 11 and 14. Check out those videos. They should help!

[@yanirmt22]

thanks a lot... it makes my review so easy to understand... God bless

[@Bindasjhakyass]

What is action potential duration? What is the difference between APD and ERP?

[@chemistrygelareh]

Absolutely helpful

[@MissAnnieDreamer]

You're amazing, thank you for the great vids! So helpful~

[@InteractiveBiology]

@wackomackopaco You're welcome! Please stay tuned for more Biology videos! :)

[@MsMoti93]

I totally Understood the concept xD Thank u sooooo muchhhhhhhh :D

[@osman.z.abdul-kaadir4565]

Well explained. Thank you.

[@InteractiveBiology]

You are welcome. Make sure to subscribe for more.

[@fehmeedaayoub6559]

I am not able to understand the tranfer of action potential across axon?? How myelinated nerve fibers are fast conductors and non myelinated are slow conductors.

[@unitedsalsa2305]

this was so helpful thank you

[@angie_revels_]

perfectly explained, thank youuu

[@JBitzz]

Hey I heard ur interview on the Smart Passive Income podcast!! Now I'm studying for my neurophysiology midterm and I coincidentally stumbled to your videos haha. Th

[@leratonogabe]

Thank you so much for this!

[@InteractiveBiology]

You are very much welcome @@leratonogabe. Glad you got value from it. Make sure to subscribe to the channel, because I have a lot more content like this coming to help you understand how the human body works 👍🏽.

[@mazenmonim7024]

thank you sir for this video

[@colacasados]

Hello, and THANK YOU for your videos!!! They truly simplify information. Would you happen to have videos on ALL of the characteristics of Action Potential (including "nondecremental" & "irreversible")?

[@ksufler]

Hello, first of all for the great and informative video, I think I'm getting it except one thing. I'm having a hard time understanding the RRP. You said that with only a few Na channels closed it takes a much more stronger stimulus to cause the deporarization again.. but logically it should be easier to open the lesser number of channels, than to open them all when they are all closed in the initial state.. I don't understand :c

[@HxAlabdulla]

dear, as I know you must open all the channels to get the right amount of stimulation in order to get a response..it should be the same amount as the previous stimulation... hope I'm right, this what I understand from the lecture

[@Shnikey]

ksufler, an older example of relative refractory period is this: envision the flushing of a toilet bowl. upon first flush, the response is very strong, full flush occurs no problem (full depolarization, action potential). In the middle of this flush, you can push your toilet handle again and you will get no response from the toilet (absolute refractory period). but if you wait just past the midpoint of the first flush, you can actually push the handle again, but much harder to get it to start the flush process all over again (relative refractory). thus, relative refractory period is that state when you've already flushed the toilet, and need to exert greater force to flush again before the first flush has finished (returned to resting state). I hope this helps you understand the concepts and why a larger than greater force/stimulus is required to generate another action potential.

[@HxAlabdulla]

exactly thanks for relating this example to real life .. yeah I got it !! good luck to everyone :)

[@mohammadsammie4712]

HamdaSaeed 11s3 It might also be because the K+ efflux making the depolarization Harder and with a Portion of Na+ gates Inactivated there must be a stronger stimulus.

[@Reimitsuo]

Great explanation!

[@InteractiveBiology]

Thanks, @Rei Mitsuo. Glad you found it helpful. Make sure to subscribe to the channel, because I have a lot more content like this coming to help you understand how the human body works.

[@InteractiveBiology]

@crackowacko87 I do have those videos, check out episodes 45 - 47. I deal with those topics there. All the best!