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011 Hyperpolarization: Last phase of the Action Potential

First there’s Depolarization, then Repolarization and finally – Hyperpolarization. Want to know what it’s all about? Watch the video.

It’s only 2 minutes and 33 seconds, but it packs a punch.

Any Questions or Comments? Leave them in the comments section below.

- Leslie Samuel

Transcript of Today’s Episode

Hello and welcome to Interactive Biology TV, where we’re making biology fun! My name is Leslie Samuel, as usual. In this episode, Episode 11, we’re going to be talking about the last phase of the action potential, and that’s called hyperpolarization. If you watched the previous two episodes, we spoke about the first two phases, depolarization and repolarization. Now we’re talking about the last phase, hyperpolarization. Where we ended off in the last episode, potassium was rushing out of the cell, because voltage-gated potassium ion channels opened, and potassium wanted to leave, so potassium is now gone.

Now, potassium, as it’s going out of the cell, it’s trying to reach its equilibrium potential, which is somewhere around -93 millivolts. The resting membrane potential is somewhere around -70 millivolts, so we’re going lower than that resting membrane potential, and that process is called hyperpolarization. In other words, it’s over-polarized. It’s overshooting the resting membrane potential and going even more negative towards the equilibrium potential for potassium, because that’s where potassium wants to be.

Now, once we start heading towards that really negative -93 millivolts, there’s another process that’s still happening in the background, and that’s the sodium-potassium pump. It’s still doing its work. If you remember what that is, from the episode where we talked about the channels in the membrane, the proteins in the membrane, the sodium-potassium pump pumps 3 sodium ions out, and it pumps 2 potassium ions in. What that does as it’s working is it brings that membrane potential right back around the resting membrane potential. That’s the end of the action potential.

So we have depolarization, repolarization, hyperpolarization, and then the sodium-potassium pump doing its job to bring it back to resting situations. That’s it for this video, and if you have questions, you can go ahead and leave them in the comments below. I’ll be happy to take a look at those and maybe even answer it in a video like this. That’s all for this video, and I’ll see you in the next one.

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Leslie Samuel is the creator of Interactive Biology. His mission is to use this site to Make Biology fun for people all over the world.

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Leave An AWESOME Comment

170 Responses to “011 Hyperpolarization: Last phase of the Action Potential”

  1. sara January 14, 2011 at 2:04 pm #

    thanks alot , :):)

    • Leslie January 14, 2011 at 2:43 pm #

      You are very much welcome Sara :D

    • Critical Care RN March 17, 2012 at 2:25 pm #

      Are you married?

  2. Kendra51391 January 26, 2011 at 11:29 pm #

    Thanks so much for this! I was having trouble learning this stuff out of
    the textbook and your explanation was really clear and easy to understand.
    Fantastic!

  3. RSM March 20, 2011 at 7:49 pm #

    Thank You So Very Much!! This was Greekology when my Professor was teaching it. How awesome, I expect to pass this module have been really struggling with the first few, but I am glad I found you Samuel. You are so humble yet so smart and talented. May God bless your soul as you continue to help all those who need your help!!

    • Leslie March 20, 2011 at 8:16 pm #

      That’s awesome. I’m so glad that the video was able to help you understand the concept. Feel free to share it with your classmates :)

      Blessings to you!

  4. James92 May 2, 2011 at 6:10 am #

    One of the best teachers I’ve ever come across! Amazing explanations and demonstrations…thank you :)

    • Lrsamuel May 2, 2011 at 7:54 am #

      Thanks James. I’m glad you are getting value from the videos :)

      Stay tuned for MANY more!

  5. Imran May 29, 2011 at 6:17 am #

    Thank you that really helped!
    But I have a question I have been wondering about…
    Why do the Potassium ion channels remain open throughout repolarization and depolarisation? In a book i have been reading in, it says they remain open throughout.

    • Lrsamuel May 29, 2011 at 8:00 am #

      Potassium channels aren’t open during depolarization. They open during depolarization and they stay open until the Membrane Potential gets low enough. However, they do start closing during repolarization as the voltage decreases. It’s like this: High membrane potential – open. Low Membrane potential – Close. Check out the video on Repolarization.

  6. Jab1113 June 2, 2011 at 9:02 pm #

    LIKE this if you are a visual learner and hate reading textbooks!

  7. InteractiveBiology June 4, 2011 at 9:17 pm #

    @Jab1113 Glad you like :)

  8. rich longo July 12, 2011 at 7:08 pm #

    Thank you so much!!! You made this subject so simple to comprehend

  9. tbabigal September 6, 2011 at 12:54 am #

    Thanks a lot Mr. Leslie, u were of great help!! God bless you!!

  10. shaista saiyad September 9, 2011 at 10:52 am #

    ‘During hyperpolarisation, membrane potential inside is less than
    -70mv.say about -72mv. it is then brought back to resting -70mv by sodium potassium pump.’my ques is, if Na-K pump starts working at hyperpolarising state, it should create more negativity inside (as it pushes 3 Na+ out in exchange of 2 K+ inside. thus creating more negativity inside).Then how does the pump brings back the potential to -70mv from -72mv??

    • Lrsamuel September 23, 2011 at 8:42 am #

      All questions are answered in the Interactive Biology community forums from now on. This is to make it as efficient as possible as we have multiple people over there to help answer questions.

      All the best

  11. Sami Jadmani September 15, 2011 at 12:18 am #

    Thank you for making it visual with the marbles and plus signs. It really
    helped clarify my confusion =)

  12. InteractiveBiology September 28, 2011 at 6:17 pm #

    @yavneh911 So glad to be able to help :)

  13. InteractiveBiology September 28, 2011 at 6:17 pm #

    @MatthewJosephFlahert That’s because I have a nose :D

  14. sathyahema October 28, 2011 at 9:27 pm #

    God Bless you for making these videos, Mr. Samuel !!! They are so helpful and I am going to share your videos with my classmates too :)!

  15. sathyahema October 28, 2011 at 9:27 pm #

    God Bless you for making these videos, Mr. Samuel !!! They are so helpful and I am going to share your videos with my classmates too :)!

  16. Lyeaest November 3, 2011 at 4:36 am #

    How does pumping 3 Na out and 2 K in make the membrane potential more positive? Sounds like it would leave you with a -1 charge, making it more negative…..

  17. lovelylatina207 November 5, 2011 at 7:13 pm #

    You’re so cool!!!

  18. AznViperXT November 6, 2011 at 8:35 pm #

    Thanks Leslie, I wish professors could explain it as well as you do!

  19. Runningman November 6, 2011 at 8:35 pm #

    Thanks Leslie, I wish professors could explain it as well as you do!

  20. InteractiveBiology November 7, 2011 at 9:22 am #

    @lovelylatina207 Leslie is indeed the best in what he does. Stay tuned for more cool Biology videos coming very soon!

  21. InteractiveBiology November 7, 2011 at 9:24 am #

    @AznViperXT Thank you! We’ll let Leslie know how much you appreciate his way of sharing knowledge with everyone :) Stay tuned for more because there’ll be a lot more Biology videos coming very soon… Enjoy!

  22. InteractiveBiology November 7, 2011 at 9:26 am #

    @sathyahema Thank you so much! There’ll be more Biology videos coming soon, so stay tuned!

  23. FantasyGrl317 November 9, 2011 at 9:49 am #

    Thank you so much for making these videos!! They are so helpfull!!

  24. InteractiveBiology November 9, 2011 at 10:44 am #

    @FantasyGrl317 And, thank you too for your support! :) You can go to our website for more Biology videos that you might find interesting. We guarantee you, you’ll learn and understand concepts easily. Stay tuned for more!

  25. hmelton1247 November 9, 2011 at 6:12 pm #

    Thank you so much for this! I’m taking Anatomy & Physiology right now and we started the nervous system last week. I have understood everything until we got to Hyper-polarization. I couldn’t figure out how we were going from about -90 mV to about -70 mV (less negative, therefore more positive) by decreasing the number of positive ions. But after watching your video about Donnan Equilibtium and this one, I finally get it!!! This has really helped! Thank you sooo much!

  26. hmelton1247 November 9, 2011 at 6:12 pm #

    Thank you so much for this! I’m taking Anatomy & Physiology right now and
    we started the nervous system last week. I have understood everything until
    we got to Hyper-polarization. I couldn’t figure out how we were going from
    about -90 mV to about -70 mV (less negative, therefore more positive) by
    decreasing the number of positive ions. But after watching your video about
    Donnan Equilibtium and this one, I finally get it!!! This has really
    helped! Thank you sooo much!

  27. InteractiveBiology November 10, 2011 at 1:05 pm #

    @hmelton1247 You’re very much welcome! We are glad to know that you found value on this video and was able to help out. Do come back for more because there are a lot more videos coming very soon! :)

  28. efil4aggin92 November 13, 2011 at 5:47 pm #

    I just subbed you and i hope that your videos will help me until i get my masters!!

  29. InteractiveBiology November 14, 2011 at 10:49 am #

    @efil4aggin92 Well, definitely! Leslie will be there still sharing his knowledge and expertise with everyone as long as he can… have fun and stay tuned for more!

  30. skinnimelon November 14, 2011 at 3:48 pm #

    @Lyeaest I’m having the same question indeed…

  31. skinnimelon November 14, 2011 at 3:58 pm #

    I understand that the pump brings 2K+ back into the membrane because too much K+ going out the cell membrane but not the part that 3Na+ going out and altogether increasing the membrane potential

  32. skinnimelon November 14, 2011 at 4:01 pm #

    @skinnimelon *should be into / out of the cell (axon)

  33. skinnimelon November 14, 2011 at 4:01 pm #

    @skinnimelon *should be into / out of the cell (axon)

  34. BDdiva1 November 14, 2011 at 8:43 pm #

    after watching i felt like killing myself for wasting my whole day and night trying to understand from the books this action potential and neurons. Mashallah God bless you dear. Thank you so much for helping :D

  35. InteractiveBiology November 16, 2011 at 6:26 am #

    @BDdiva1 You’re very much welcome! We’re glad to know the videos have been able to help. Do stay tuned because we have more Biology videos coming very soon!

  36. InteractiveBiology November 16, 2011 at 6:26 am #

    You’re very much welcome! We’re glad to know the videos have been able to help. Do stay tuned because we have more Biology videos coming very soon!

  37. InteractiveBiology November 16, 2011 at 6:26 am #

    @BDdiva1 You’re very much welcome! We’re glad to know the videos have been
    able to help. Do stay tuned because we have more Biology videos coming very
    soon!

  38. zai4booc November 28, 2011 at 7:14 pm #

    @InteractiveBiology Thank you so much,

  39. zai4booc November 28, 2011 at 7:14 pm #

    Thank you so much,

  40. zai4booc November 28, 2011 at 7:14 pm #

    Thank you so much,

  41. InteractiveBiology November 28, 2011 at 11:49 pm #

    @zai4booc You’re welcome! :)

  42. InteractiveBiology November 28, 2011 at 11:49 pm #

    You’re welcome! :)

  43. NeedsAHardOne November 29, 2011 at 5:32 pm #

    @efil4aggin92
    I CANNOT agree with you more lol

  44. NeedsAHardOne November 29, 2011 at 5:32 pm #

    I CANNOT agree with you more lol

  45. goozbye December 4, 2011 at 6:21 pm #

    @Jab1113 OH man I am sooo a visual learner and I didn’t understand the cacashit textbooks were talking about.

  46. goozbye December 4, 2011 at 6:21 pm #

    OH man I am sooo a visual learner and I didn’t understand the cacashit textbooks were talking about.

  47. Donya Eghbali December 4, 2011 at 6:21 pm #

    @Jab1113 OH man I am sooo a visual learner and I didn’t understand the
    cacashit textbooks were talking about.

  48. Zer0PvM December 7, 2011 at 9:56 pm #

    fuck a text book whats the point of going to lectures when i cant fully understand whats going on you are the man keep doing what your doing

  49. Zer0PvM December 7, 2011 at 9:56 pm #

    fuck a text book whats the point of going to lectures when i cant fully
    understand whats going on you are the man keep doing what your doing

  50. InteractiveBiology December 8, 2011 at 3:21 pm #

    @Zer0PvM THank you! More Biology videos can be found in our website, PLease stay tuned for more !

  51. InteractiveBiology December 8, 2011 at 3:21 pm #

    THank you! More Biology videos can be found in our website, PLease stay tuned for more !

  52. InteractiveBiology December 8, 2011 at 3:21 pm #

    THank you! More Biology videos can be found in our website, PLease stay tuned for more !

  53. lilsk8rboy December 12, 2011 at 3:41 am #

    can’t believe this nigga is explaining this shit

  54. adityadevil0007 December 25, 2011 at 11:34 am #

    Thank you for your amazing videos.

  55. Aditya Singh December 25, 2011 at 11:34 am #

    Thank you for your amazing videos.

  56. InteractiveBiology December 25, 2011 at 11:16 pm #

    @adityadevil0007 You’re welcome. Please stay tuned for more Biology video uploads :)

  57. InteractiveBiology December 25, 2011 at 11:16 pm #

    You’re welcome. Please stay tuned for more Biology video uploads :)

  58. InteractiveBiology December 25, 2011 at 11:16 pm #

    You’re welcome. Please stay tuned for more Biology video uploads :)

  59. InteractiveBiology December 26, 2011 at 4:16 am #

    You’re welcome. Please stay tuned for more Biology video uploads :)

  60. ninahn89 December 29, 2011 at 11:43 pm #

    Hey do you happen to know how the A-current is bought about and how it can be influences to change the rate of spike firing… thank you
    P.s revision tends to make me dislike neuro but you’ve reminded me of how much i love it .. so thank you :)

  61. ninahn89 December 30, 2011 at 4:43 am #

    Hey do you happen to know how the A-current is bought about and how it can be influences to change the rate of spike firing… thank you
    P.s revision tends to make me dislike neuro but you’ve reminded me of how much i love it .. so thank you :)

  62. Chazilla3000 January 14, 2012 at 2:24 pm #

    Very thorough, very clear, good Job!

  63. Chazilla3000 January 14, 2012 at 7:24 pm #

    Very thorough, very clear, good Job!

  64. mathyourasmussen January 18, 2012 at 12:10 pm #

    Great stuff, I really enjoy.
    Why is this last stage called hyper(polarization; a continued decrease in the membrane’s potential), when hyperthermia is an increase in one’s body temperature. It would seem that it should be called hypopolarization, similar to hypothermia (decrease in ones body temp – decrease in the membranes potential). Does it have to deal with the fact that the membrane’s potential is calculated in respect to the extracellular fluid? Thanks!

  65. mathyourasmussen January 18, 2012 at 5:10 pm #

    Great stuff, I really enjoy.
    Why is this last stage called hyper(polarization; a continued decrease in the membrane’s potential), when hyperthermia is an increase in one’s body temperature. It would seem that it should be called hypopolarization, similar to hypothermia (decrease in ones body temp – decrease in the membranes potential). Does it have to deal with the fact that the membrane’s potential is calculated in respect to the extracellular fluid? Thanks!

  66. Yvonne Mitton January 24, 2012 at 10:26 pm #

    Thank you so much for sharing your knowledge with us in an understandable way. I do have a question about the Ion channels in the plasma membrane. In your video you talk about the sodium-potassium pump. I remember learning about this when I took A&P about ten years ago. I am taking it again and in my book it does not mention this pump. Instead, it mentions the Mechanically gated channel which opens or closes in response to mechanical stimulation in the form of vibration. Just wondering why I have not read anything pertaining to the sodium-potassium pump in this 13th edition of Principles of Anatomy and Physiology by Gerard J. Tortora and Bryan Derrickson.

    • Lrsamuel January 25, 2012 at 12:18 am #

      Hmm that’s strange. Let me put that on my list of A&P books never to look at. Ok, just kidding (kinda).

      Not sure why it wouldn’t mention sodium potassium pumps. There are various types of proteins in the membrane of cells. Sodium Potassium pumps are just one of them. However, it plays a very important part when it comes to the Membrane Potential.

      Watch my video on the Ion Channels in the membrane.

      Hope that helps!

      • Yvonne January 25, 2012 at 5:30 pm #

        Ok, my bad, the sodium potassium pump is mentioned briefly in two sentences. I went back and read again today. Thank you for your videos, they help so much!

        • Lrsamuel January 25, 2012 at 10:11 pm #

          Oh ok, that makes more sense. You just have to include that pump!

  67. robincrutchfield1 January 25, 2012 at 5:41 pm #

    thank you , for helping me to understand the stages better.

    Q; the inside of the cell aslo contains proteins and negatively charged ions( does that have something to do with action potential?) My teacher wrote this on our notes but did not futher explain
    .

  68. dancernoregon January 25, 2012 at 7:09 pm #

    You are my A&P hero :)

  69. robincrutchfield1 January 25, 2012 at 10:41 pm #

    thank you , for helping me to understand the stages better.

    Q; the inside of the cell aslo contains proteins and negatively charged ions( does that have something to do with action potential?) My teacher wrote this on our notes but did not futher explain
    .

  70. nibblesxsips January 25, 2012 at 11:00 pm #

    @Jab1113 textbooks are for visual learners…

  71. nibblesxsips January 25, 2012 at 11:00 pm #

    textbooks are for visual learners…

  72. nibblesxsips January 25, 2012 at 11:00 pm #

    textbooks are for visual learners…

  73. dancernoregon January 26, 2012 at 12:09 am #

    You are my A&P hero :)

  74. nibblesxsips January 26, 2012 at 4:00 am #

    textbooks are for visual learners…

  75. jo1183 February 3, 2012 at 6:39 pm #

    Seen all of your videos about CNS all the way up to this point, your enthusiasm and perspectives have really helped me visualize biology of this sort on a new scale! keep it up your the best

    • Leslie Samuel February 4, 2012 at 7:07 pm #

      So glad to know that the videos are helping you.

      Stay tuned for more.

      All the best!

  76. KAROLL0303 February 4, 2012 at 11:18 pm #

    You are awesome! Thanks!!!

  77. KAROLL0303 February 5, 2012 at 4:18 am #

    You are awesome! Thanks!!!

  78. rayrayzim February 15, 2012 at 5:22 pm #

    i love your videos! u are a savior for making bio simple and easy to understand!!

  79. rayrayzim February 15, 2012 at 10:22 pm #

    i love your videos! u are a savior for making bio simple and easy to understand!!

  80. crazyskater4 February 16, 2012 at 8:56 pm #

    thanks so much for these videos, these helped so much!

  81. crazyskater4 February 17, 2012 at 1:56 am #

    thanks so much for these videos, these helped so much!

  82. guppyngizmo February 19, 2012 at 3:04 am #

    thank you!!! very helpful video.
    Is it correct to say then that the sodium pump is always working away in the backgound or just when there is an action potential?

  83. guppyngizmo February 19, 2012 at 8:04 am #

    thank you!!! very helpful video.
    Is it correct to say then that the sodium pump is always working away in the backgound or just when there is an action potential?

  84. wildflower0214 March 1, 2012 at 12:13 am #

    u just saved me from disaster!!!

  85. wildflower0214 March 1, 2012 at 12:13 am #

    u just saved me from disaster!!!

  86. wildflower0214 March 1, 2012 at 5:13 am #

    u just saved me from disaster!!!

  87. ItsBrianaTime March 4, 2012 at 3:22 pm #

    Thank you so much!! I couldn’t quite grasp the concept until I saw you use the white plus signs and the blue marbles. I feel much more confident about Membrane Potentials now!!

  88. bs0u31c3 March 4, 2012 at 7:02 pm #

    @Zer0PvM Textbooks are so dull and hopefully will become redundant soon. Visual learning is better because it sticks in the brain better. And yes lectures are useless i dont even know why I bother because i learn nothing. Thank God for good online teachers like this young man. Life saver.

  89. bs0u31c3 March 4, 2012 at 7:02 pm #

    Textbooks are so dull and hopefully will become redundant soon. Visual learning is better because it sticks in the brain better. And yes lectures are useless i dont even know why I bother because i learn nothing. Thank God for good online teachers like this young man. Life saver.

  90. bs0u31c3 March 4, 2012 at 7:02 pm #

    Textbooks are so dull and hopefully will become redundant soon. Visual learning is better because it sticks in the brain better. And yes lectures are useless i dont even know why I bother because i learn nothing. Thank God for good online teachers like this young man. Life saver.

  91. ItsBrianaTime March 4, 2012 at 8:22 pm #

    Thank you so much!! I couldn’t quite grasp the concept until I saw you use the white plus signs and the blue marbles. I feel much more confident about Membrane Potentials now!!

  92. bs0u31c3 March 5, 2012 at 12:02 am #

    Textbooks are so dull and hopefully will become redundant soon. Visual learning is better because it sticks in the brain better. And yes lectures are useless i dont even know why I bother because i learn nothing. Thank God for good online teachers like this young man. Life saver.

  93. greenfirekeys4 March 26, 2012 at 1:11 am #

    finally understood!

  94. greenfirekeys4 March 26, 2012 at 1:11 am #

    finally understood!

  95. greenfirekeys4 March 26, 2012 at 5:11 am #

    finally understood!

  96. ILostMyGrass March 30, 2012 at 3:39 pm #

    Please, I do not understand how hyperpolarization gains net positive charge (to return back to resting potential) when the sodium potassium pump gives out 3 Na+ ions for every 2 K+ ions taken in.

  97. ILostMyGrass March 30, 2012 at 7:39 pm #

    Please, I do not understand how hyperpolarization gains net positive charge (to return back to resting potential) when the sodium potassium pump gives out 3 Na+ ions for every 2 K+ ions taken in.

  98. ILostMyGrass March 31, 2012 at 10:52 am #

    Ah nevermind. Hyperpolarization; sodium voltage gate’s inactivation gate closes, therefore decreasing Na+ permeability while K+ permeability increases. A net loss of K+ and positive charge by the cell is induced then.

  99. ILostMyGrass March 31, 2012 at 2:52 pm #

    Ah nevermind. Hyperpolarization; sodium voltage gate’s inactivation gate closes, therefore decreasing Na+ permeability while K+ permeability increases. A net loss of K+ and positive charge by the cell is induced then.

  100. mullahnasruddinQQ April 6, 2012 at 3:35 pm #

    My oh my, you are a gifted lecturer. I will show up for more of your vids.
    Kind regards from good old germany.

  101. mullahnasruddinQQ April 6, 2012 at 7:35 pm #

    My oh my, you are a gifted lecturer. I will show up for more of your vids.
    Kind regards from good old germany.

  102. NABHenry April 8, 2012 at 6:40 pm #

    You have taken the complicated activities of the body and broken them down to plain simple processes. Without a doubt the most informative teaching/instruction I have ever received!

  103. NABHenry April 8, 2012 at 10:40 pm #

    You have taken the complicated activities of the body and broken them down to plain simple processes. Without a doubt the most informative teaching/instruction I have ever received!

  104. silverlining723 April 16, 2012 at 1:32 am #

    What amazing videos! I’ve watched all of the action potential videos after trying to understand this concept by listeing to my class lectures, reading my notes and text book and looking at the diagrams. I find your videos and ten minutes later I’ve got it! I’m in a 200 level college bio class! I’ll be telling my class mates about this video for sure!

  105. silverlining723 April 16, 2012 at 5:32 am #

    What amazing videos! I’ve watched all of the action potential videos after trying to understand this concept by listeing to my class lectures, reading my notes and text book and looking at the diagrams. I find your videos and ten minutes later I’ve got it! I’m in a 200 level college bio class! I’ll be telling my class mates about this video for sure!

  106. MegaCorky09 April 16, 2012 at 5:50 pm #

    thank you for your videos they have helped so much

  107. MegaCorky09 April 16, 2012 at 9:50 pm #

    thank you for your videos they have helped so much

  108. Foinnse April 22, 2012 at 1:14 pm #

    You, Leslie Samuel, are a king among men. Thank you.

  109. Foinnse April 22, 2012 at 5:14 pm #

    You, Leslie Samuel, are a king among men. Thank you.

  110. teabag5 May 10, 2012 at 11:10 am #

    Your videos are incredibly helpful! Thank you. I do have a question though. Can the Potassium ions move before the Sodium ions or do the Sodium ions always move first? My notes seem to suggest that the potassium is switching first, as it shows a trough in the millivolts graph before the peak as Sodium rushes in, rather than after it.

    Many thanks

  111. teabag5 May 10, 2012 at 11:10 am #

    Your videos are incredibly helpful! Thank you. I do have a question though. Can the Potassium ions move before the Sodium ions or do the Sodium ions always move first? My notes seem to suggest that the potassium is switching first, as it shows a trough in the millivolts graph before the peak as Sodium rushes in, rather than after it.

    Many thanks

  112. EroticKawaii May 31, 2012 at 12:41 am #

    you have nice teeth

  113. EroticKawaii May 31, 2012 at 12:41 am #

    you have nice teeth

  114. MrKwnnos June 14, 2012 at 9:00 am #

    You are exactly the guy that I was expecting to make a website and channel in youtube named “Make Biology Fun”. You are perfect. Congratulations. I hope all my teacher be like you.!!!!!!!!!

  115. MrKwnnos June 14, 2012 at 9:00 am #

    You are exactly the guy that I was expecting to make a website and channel in youtube named “Make Biology Fun”. You are perfect. Congratulations. I hope all my teacher be like you.!!!!!!!!!

  116. NiMI July 1, 2012 at 8:12 pm #

    Hi the videos are really good it help me lot , but i have question what is refractory period

  117. celiletare August 11, 2012 at 6:06 pm #

    Thank you! It now makes sense!

  118. mathelida September 5, 2012 at 7:44 pm #

    can anybody tell me..?how to directly contact with Mr.leslie samuel??? thanks

  119. InteractiveBiology September 6, 2012 at 8:38 am #

    At the Interactive Biology website, you’ll find a “contact me” page where you can send Prof. Leslie Samuel a message. Thank you!

  120. mathelida September 6, 2012 at 10:50 am #

    oh thank you so much ! .. :)

  121. mathelida September 7, 2012 at 9:53 pm #

    ohh guys!! he is not replying…and i want soon :(

  122. SplashFlip October 6, 2012 at 2:09 pm #

    I AM STARTING TO HATE MY LEACTURER!!! Watching these videos are so much easier and clearer!!!

  123. olgamodel2004 October 9, 2012 at 8:54 pm #

    You are awesome!!! Thank you!

  124. Davi Dorval October 13, 2012 at 6:19 pm #

    awesome!!

  125. Tim Hernandez October 17, 2012 at 5:45 am #

    Thanks a ton, that makes makes so much more sense now.

  126. Kasia Hojsan October 31, 2012 at 12:29 am #

    Thank you! Smart and Cute! lol

  127. LivingOracles November 2, 2012 at 12:07 am #

    i never thought i would be able to understand this until i watched your videos u are a legend!

  128. Md Mamunur Rashid November 27, 2012 at 6:55 am #

    Very very nice!!!

  129. Beth Botwin December 11, 2012 at 11:07 am #

    Thank you so much for this! I’m studying for my A&P final and I was struggling with this part. I had an “Oooooh! I get it!” moment while watching this. Thanks again! :)

  130. ali aldujaili December 17, 2012 at 9:14 am #

    thanks man

  131. Abbigayle Brown January 5, 2013 at 1:54 pm #

    These videos have helped me so much! Better than any textbook! Thankyou.

  132. DAHRealTrump January 16, 2013 at 5:17 am #

    Thank you! Thank you! Thank you! Thank you! You cleared everything up! I didn’t even have questions lingering in my mind after this video! Great teaching skills!

  133. Judith Koerselman January 25, 2013 at 12:36 pm #

    I am so greatful for your videos! You have a great way of explaining difficult subjects!

  134. russtery89 February 13, 2013 at 1:48 am #

    This is what all my college professors are missing in their lectures…teaching with a smile on their face! thanks for the video!

  135. TheDonnaMiranda February 14, 2013 at 8:33 pm #

    You’re so cute :)

    Now I can’t focus >.<

  136. Maria Kukushina February 18, 2013 at 3:39 pm #

    great job, thanx a lot:) watching you for two hours b4 test

  137. mmiracleofGod February 24, 2013 at 12:57 am #

    Thank you Professor. I watch your videos over & over for my neurology class. I like that your videos break concepts down into bit sized pieces.

  138. sarahmcfarland29 February 24, 2013 at 1:43 am #

    WOW! That’s it. I get it now!!! Thank you!

  139. Kenny Morse March 5, 2013 at 6:56 pm #

    Thanks a lot, this was a big help.

  140. emily missler March 8, 2013 at 1:24 pm #

    Amazing…Now I finally get it.

  141. chocolateddy22 March 9, 2013 at 10:16 pm #

    this is sooo amazing and well explained!! I have hope that I’ll pass my course now!!

  142. Moukhtar Nassabi March 12, 2013 at 4:38 pm #

    awesome videos….. helped allot… thanks :D

  143. memo shine March 25, 2013 at 7:48 pm #

    thanks leslie

  144. Linda Holder April 13, 2013 at 2:01 pm #

    What happens if you have hyperkalemia, how does it affect the action potential??

  145. JJvideoman April 23, 2013 at 11:35 pm #

    Wow I was staring at a lecture slide for 15 minutes trying to get my head around this chart im looking at with depolar, repolar etc. Shoulda saved my 15 minutes and come straight to you now it makes sense!! Cheers mate.

  146. Marbelis Morejon July 18, 2013 at 12:51 pm #

    thank you so much…everything is clear now … amazing ;)

  147. Antanas Páramo July 23, 2013 at 10:19 am #

    you’re the best man!

  148. Nathalie Cladera August 28, 2013 at 1:12 am #

    I love your patience and how you relate to the slow process of AP and BIology student brains, in the words of oliver twist, may i have some more sir, please.

  149. Tina46796 September 10, 2013 at 11:32 pm #

    WOW! Life seems a lot easier. I had so mush trouble understanding all these re/de/ hypo /polarization. Now I am sure wake me up in the middle of the night I will be more than happy to tell you all about them:)) THANK YOU SO MUCH!!!

  150. Mark Anthony .Ramos September 25, 2013 at 7:43 pm #

    If 3 sodium ions go out and 2 potassium ions go in, wouldn’t the end result be negative? So wouldn’t this push the line further below the resting state?

  151. qymj October 2, 2013 at 1:08 am #

    Thank you so much

  152. Chilakala pavan October 7, 2013 at 2:03 pm #

    can u kindly give information on AFTER DEPOLARISATION,AND EXACTLY FROM WHICH POINT OF REPOLARISATION DOES THE RELATIVE REFRACTORY PERIOD STARTS AND ENDS

  153. Stephanie Conley October 8, 2013 at 10:26 am #

    Ok. Hours in lectures and could not understand this. 15 minutes watching your videos and now I understand. THANKS!!!

  154. nathanb605 October 14, 2013 at 8:12 pm #

    love this man

  155. DrAbd El-RaHmAn November 16, 2013 at 6:18 pm #

    you great man
    i love watch you and really i understand all thing from u

  156. Daphne Clarke December 12, 2013 at 4:08 pm #

    Hi Leslie, can you please explain to me how the sodium potassium pump works? I have an exam on the 18th of December and one of the topics is on the action potential and neurons.

  157. towfiq December 14, 2013 at 12:07 pm #

    you make biology so easy for me
    can you explain to me what the sensory taste pathway is?

  158. Ellie May 3, 2014 at 1:58 am #

    Hi Leslie,

    Thank you SO much! I have not for the life of me been able to work out action potential and the depolarisation, repolarisation process until right now! Your videos make what I’m sure is a very complicated process, seem so simple and easy to understand.

    Thanks for doing what you’re doing and making it fun : ). There are definitely a lot of people benefiting from your knowledge.

    Really appreciate it.

    Ellie