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019 What is Summation? (2 Types)

When post-synaptic potentials reach the neuron, they can be added up through the process of summation.

Watch as Leslie explains this process and expounds on the 2 types of summation.

Enjoy!

Transcript of Today’s Episode

Welcome to another episode of Interactive Biology TV, where we’re making biology fun! My name is Leslie Samuel. In this episode, Episode 19, I’m going to be answering the question “What is summation?” and I’m going to talk about the 2 types of summation. So let’s get right into it.

Summation is basically the addition of post-synaptic potentials. To illustrate this, I’m going to draw our membrane potential graph, with membrane potential on the Y-axis, Em, and time on the X-axis. I’m going to start with our resting membrane potential somewhere around -70 millivolts, so let’s say this is -70. Now, we’ve spoken about threshold, and we said that in order for there to be an action potential, the membrane potential needs to reach that threshold, and I’m going to say that’s around -55 millivolts.

So an action potential comes down an axon, it reaches the axon terminals, neurotransmitters are released, and that causes an excitatory post-synaptic potential in the post-synaptic cell. What you’re going to see there is there’s going to be a little bump in the membrane potential. We know that the threshold is up here, so that bump is not going to be enough to cause an action potential.

So what needs to happen is we get an excitatory post-synaptic action potential, and before the first one finishes, another one comes along, raising the membrane potential even more, and that process continues over and over until eventually, we have enough stimulation to cause the membrane potential to reach threshold. And then, we get the action potential with our depolarization, our repolarization, our hyperpolarization, and then the action potential is finished.

So that’s what we’re talking about with summation. We’re basically adding these post-synaptic potentials. Remember, sometimes we can get excitatory post-synaptic potentials, we can get inhibitory post-synaptic potentials that bring our membrane potential even further away from the threshold. But we’re basically adding them so that we can reach that -55 millivolt threshold and cause an action potential.

With that understanding, let’s look at the 2 types of summation:
1. Temporal summation
2. Spatial summation
I’m going to do a drawing to illustrate both. With temporal summation, what we have is a pre-synaptic neuron, so let’s just draw an axon, and I’m going to simplify it by making just 1 axon terminal, and that makes a synapse with a post-synaptic neuron, so here’s my neuron. Here we have the soma, and here we have the axon. What happens is a signal comes along this axon, comes to the axon terminal, releases neurotransmitters, and that causes an excitatory post-synaptic potential in this cell. That is where we see the first bump. Now, if it sends that signal and it sends another one quickly and it continues doing that, that’s going to cause the membrane potential to go up and up until it reaches the threshold and causes the action potential. This is temporal summation.

Now, that’s different from spatial summation. With spatial summation, we have an axon here, and I’m just going to draw 1 axon with 1 terminal, of course that’s simplified, that connects to another neuron. However, we also have another axon that comes and we have an axon terminal that connects to the same neuron.

What’s going to happen here is this one can cause a signal, an excitatory post-synaptic potential, and before that dies off, we can have another signal coming from this other cell. So we have 2 separate neurons causing responses in this cell, and of course, we get the same result where the membrane potential goes up, and when the next one fires, it goes up again, and this one can fire again, that causes it to go up, and then it eventually reaches the threshold, causing our action potential. That is spatial summation.

So an easy way for you to remember this, at least this is what works for me, spatial summation is separated by space, because we have 2 separate neurons that are firing. Temporal summation is the same neuron firing, but each signal is separated by time. So temporal summation is separated by time, same neuron. Spatial summation is separated by space, because there are 2 separate neurons.

That’s all the content for this video. We’ve looked at the 2 types of summation and we’ve answered the question “What is summation?” If you have any questions, go ahead and leave a comment below, and I’d be happy to get to it. That’s it 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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150 Responses to “019 What is Summation? (2 Types)”

  1. Christopher Albergo January 27, 2011 at 2:11 am #

    nice little clarification video, thanks for posting :D

  2. allison adams January 27, 2011 at 10:12 am #

    Thank you so much for this video!! It really helped me understand the difference!

    • Leslie January 27, 2011 at 10:21 am #

      That’s awesome Allison. Glad it helped you to understand the difference. Keep checking back because I’m trying to post new videos almost every weekday. So all the best with your learning :)

  3. InteractiveBiology February 5, 2011 at 8:38 pm #

    @LotesseElfin You are welcome :) Check out my website for more content.

  4. Isabelle Nguyen February 7, 2011 at 12:10 am #

    omg.. YOU ARE A LIFE SAVER!!!! Wow wonderful video! I really understand it
    now. reading it from notes and a textbook is nothing compared to visual and
    explaining. It really feels good to actually know whats going on now :)
    thanks a lot

  5. xxmusicluvv March 12, 2011 at 8:33 pm #

    this is WONDERFUL! thank you so much :) :) completely understood the
    content that I was struggling to learn by reading!

  6. InteractiveBiology March 12, 2011 at 8:34 pm #

    @porkybunbun604 You are welcome!

  7. InteractiveBiology March 29, 2011 at 5:51 am #

    @25Robbo25 You are welcome a million. Glad you are finding value in the
    content. All the best!

  8. Anita Gabriela Pardo April 19, 2011 at 11:26 pm #

    Thank you so much ! You amazing ! amazing ! so amazing ! :D You the best :D
    the best . I was so confused in my two hour class and I understand
    everything is a 6 min video :O God bless you.

  9. InteractiveBiology April 19, 2011 at 11:26 pm #

    @heregod That’s great. Glad to hear that the video helped you so much :)

  10. biology lover April 20, 2011 at 5:11 am #

    great explanation..
    by the way i still cant understand what mean by generator potential.. so can u explain that to me?

    • Leslie April 20, 2011 at 9:07 am #

      A generator potential is the same as a receptor potential. It happens in certain sensory receptors and is graded. In other words, it varies depending on the strength of the stimulus. When it reaches threshold, it causes an action potential in the sensory neuron.

      Hope that helps!

      • biology lover April 20, 2011 at 9:16 am #

        i see.. thanks for the reply..

        • Leslie April 20, 2011 at 12:16 pm #

          You are very much welcome :)

  11. Allison B April 30, 2011 at 5:11 am #

    Thanks you explain it better than a text book because I am a visual learner

    • Lrsamuel April 30, 2011 at 7:56 pm #

      You are very much welcome. Glad to know it’s helping!

  12. Blessing May 5, 2011 at 11:01 pm #

    Hello! This is a wonderful site and video, but I have a few questions.
    Exactly where is the synaptic cleft between? An axon terminal and the soma?
    Also, can there be an action potential passed to a non-neuron body cell? Or action potentials are only passing from neuron to neuron? If that is true, then what are some of the effects neurotransmitters have on non-neuron body cells when they pass into them?
    Thanks so much!

    • Lrsamuel May 9, 2011 at 1:27 pm #

      Hi Blessing. Some of your questions are answered in previous episodes.
      1. The parts of a neuron – http://www.interactive-biology.com/164/
      2. Action potentials only happen in neurons. However, there are membrane potential changes that can happen in any cell. That changes the charge across the membrane but does not result in an action potential. It can result in other things. For an example, check out what happens in the eyes – http://www.interactive-biology.com/1862/

      Hope that helps!

  13. Emelyme June 6, 2011 at 1:22 pm #

    Very well explained…. and my question is can we then say that every
    action potential generated is a result of summation??

  14. Jay S June 19, 2011 at 6:33 pm #

    thank you. it really enhanced my understanding what I want to ask now is
    that doesn’t each neurone end in several synaptic knobs and the
    pre-synaptic membrane is at the end of the synptic knob. So, could it be
    that synaptic knobs of the same neurone release neurotransmitter ?

  15. MJCastellanos November 7, 2011 at 12:12 pm #

    Making Biology fun? Undestandable, but not fun :)

  16. MJCastellanos November 7, 2011 at 12:12 pm #

    Making Biology fun? Undestandable, but not fun :)

  17. InteractiveBiology November 7, 2011 at 12:19 pm #

    @MJCastellanos :) Hope you keep coming back. Stay tuned because we have more Biology videos coming very soon!

  18. raru9086 November 7, 2011 at 3:40 pm #

    I am in truly madly deeply in love with your videos ….

    Regards,
    Your Fan

  19. InteractiveBiology November 8, 2011 at 4:19 am #

    @raru9086 Oh, thank you! Please come back for more Biology videos. Leslie plans to create more for everyone to use :)

  20. stareleades November 9, 2011 at 9:45 pm #

    If you could do shunting and reversal potentials that would be great , time constant and length constant :)

  21. stareleades November 9, 2011 at 9:45 pm #

    @stareleades also please**

  22. stareleades November 9, 2011 at 9:45 pm #

    @stareleades also please**

  23. InteractiveBiology November 10, 2011 at 1:09 pm #

    @stareleades Unfortunately, Leslie is no longer taking requests for specific videos, but he will definitely get to more systems and more Biology topics in the future. He has many to work on at the moment. So stay tuned for more. :)

  24. afrprincess07 November 20, 2011 at 4:08 pm #

    i love you!!

  25. afrprincess07 November 20, 2011 at 4:08 pm #

    i love you!!

  26. InteractiveBiology November 20, 2011 at 4:12 pm #

    @afrprincess07 Glad you liked the video. Please stay tuned for more Biology
    videos coming very soon!

  27. InteractiveBiology November 20, 2011 at 4:12 pm #

    @afrprincess07 Glad you liked the video. Please stay tuned for more Biology videos coming very soon!

  28. InteractiveBiology November 20, 2011 at 4:12 pm #

    Glad you liked the video. Please stay tuned for more Biology videos coming very soon!

  29. mycee04 November 21, 2011 at 11:23 pm #

    this is very helpful, thank you so much for putting this video up!!! do you teach by the way? if you do i need to sign up for YOUR classes!

  30. InteractiveBiology November 22, 2011 at 6:42 am #

    @mycee04 Glad to know it helped. Yes, actually, Leslie is an assistant professor at the Andrews University :)

  31. InteractiveBiology November 22, 2011 at 6:42 am #

    Glad to know it helped. Yes, actually, Leslie is an assistant professor at the Andrews University :)

  32. Rocky20186 November 22, 2011 at 3:52 pm #

    thank you so much

  33. InteractiveBiology November 23, 2011 at 8:39 am #

    @Rocky20186 You’re welcome! Please stay tuned for more biology videos :)

  34. InteractiveBiology November 23, 2011 at 8:39 am #

    You’re welcome! Please stay tuned for more biology videos :)

  35. zai4booc November 28, 2011 at 1:51 pm #

    Thank you so much. You are making my life so much easier god bless you Samuel :)

  36. InteractiveBiology November 28, 2011 at 4:13 pm #

    @zai4booc You’re welcome! Glad you’re finding value in them. Please stay tuned. WE have more Biology videos to be uploaded to the site very soon!

  37. InteractiveBiology November 28, 2011 at 4:13 pm #

    You’re welcome! Glad you’re finding value in them. Please stay tuned. WE have more Biology videos to be uploaded to the site very soon!

  38. Natalie T December 2, 2011 at 10:01 pm #

    Wow. Thank you.

  39. Luvely10891 December 2, 2011 at 10:01 pm #

    Wow. Thank you.

  40. InteractiveBiology December 4, 2011 at 9:47 am #

    @Luvely10891 You’re welcome! Stay tuned for more :)

  41. InteractiveBiology December 4, 2011 at 9:47 am #

    You’re welcome! Stay tuned for more :)

  42. InteractiveBiology December 4, 2011 at 2:47 pm #

    You’re welcome! Stay tuned for more :)

  43. pinkash1283 December 5, 2011 at 6:14 pm #

    Thank you for this video! I could not understand what summation was the way my A&P book explained, but it totally makes sense now…. and it seems so simple now ;)

  44. pinkash1283 December 5, 2011 at 11:14 pm #

    Thank you for this video! I could not understand what summation was the way my A&P book explained, but it totally makes sense now…. and it seems so simple now ;)

  45. AnUnlimitedRecord December 6, 2011 at 1:19 am #

    You are the shit! =]

  46. Deepak Nk December 6, 2011 at 6:19 am #

    You are the shit! =]

  47. Deepak Nk December 6, 2011 at 6:19 am #

    You are the shit! =]

  48. InteractiveBiology December 6, 2011 at 9:53 am #

    @pinkash1283 Glad to know that you found value on this one. You might also need other Biology videos and resources. Just head on to our site for more of them :)

  49. InteractiveBiology December 6, 2011 at 9:53 am #

    Glad to know that you found value on this one. You might also need other Biology videos and resources. Just head on to our site for more of them :)

  50. InteractiveBiology December 6, 2011 at 2:53 pm #

    Glad to know that you found value on this one. You might also need other Biology videos and resources. Just head on to our site for more of them :)

  51. anjali1129 December 11, 2011 at 2:22 pm #

    i literally felt the light bulb go on in my head…i think this is the first time i had an aha moment…thanku!lol

  52. anjali1129 December 11, 2011 at 7:22 pm #

    i literally felt the light bulb go on in my head…i think this is the first time i had an aha moment…thanku!lol

  53. InteractiveBiology December 11, 2011 at 7:36 pm #

    @anjali1129 Lol! Well, that’s good to know! Thank you for watching this video. You can go and check our other Biology videos at the site. We hope you’ll find value in them as much as you found one on this. Have fun!

  54. InteractiveBiology December 11, 2011 at 7:36 pm #

    Lol! Well, that’s good to know! Thank you for watching this video. You can go and check our other Biology videos at the site. We hope you’ll find value in them as much as you found one on this. Have fun!

  55. InteractiveBiology December 12, 2011 at 12:36 am #

    Lol! Well, that’s good to know! Thank you for watching this video. You can go and check our other Biology videos at the site. We hope you’ll find value in them as much as you found one on this. Have fun!

  56. UniGirl9008 December 17, 2011 at 7:25 am #

    Hi! Just wanted to say thank you. It was easy to understand all these. It has been a great help for my exam. Looking forward to more videos.

  57. EvelynNLB December 17, 2011 at 10:37 am #

    thanks your great!

  58. EvelynNLB December 17, 2011 at 10:37 am #

    thanks your great!

  59. EvelynNLB December 17, 2011 at 10:39 am #

    Does having a small time constant minimize the summation effect ? I don’t get how. Wouldn’t you prefer to have a small time constant in the first place.

  60. UniGirl9008 December 17, 2011 at 12:25 pm #

    Hi! Just wanted to say thank you. It was easy to understand all these. It has been a great help for my exam. Looking forward to more videos.

  61. EvelynNLB December 17, 2011 at 3:37 pm #

    thanks your great!

  62. EvelynNLB December 17, 2011 at 3:39 pm #

    Does having a small time constant minimize the summation effect ? I don’t get how. Wouldn’t you prefer to have a small time constant in the first place.

  63. InteractiveBiology December 18, 2011 at 5:24 pm #

    @EvelynNLB You’re welcome!

  64. InteractiveBiology December 18, 2011 at 5:24 pm #

    You’re welcome!

  65. InteractiveBiology December 18, 2011 at 5:26 pm #

    @EvelynNLB Sorry, Leslie won’t be able to get back to your inquiry. He’s been very loaded at the moment with a lot of work. Please do stay tuned though as he’ll be adding more Biology videos in the future. Thanks!

  66. InteractiveBiology December 18, 2011 at 5:26 pm #

    Sorry, Leslie won’t be able to get back to your inquiry. He’s been very loaded at the moment with a lot of work. Please do stay tuned though as he’ll be adding more Biology videos in the future. Thanks!

  67. InteractiveBiology December 18, 2011 at 5:27 pm #

    @UniGirl9008 Yes, definitely, there will be more videos added to the site soon. Do stay tuned!

  68. InteractiveBiology December 18, 2011 at 5:27 pm #

    Yes, definitely, there will be more videos added to the site soon. Do stay tuned!

  69. InteractiveBiology December 18, 2011 at 10:24 pm #

    You’re welcome!

  70. InteractiveBiology December 18, 2011 at 10:26 pm #

    Sorry, Leslie won’t be able to get back to your inquiry. He’s been very loaded at the moment with a lot of work. Please do stay tuned though as he’ll be adding more Biology videos in the future. Thanks!

  71. InteractiveBiology December 18, 2011 at 10:27 pm #

    Yes, definitely, there will be more videos added to the site soon. Do stay tuned!

  72. David Adejuyigbe December 29, 2011 at 9:41 am #

    Really good video, thnx

  73. sunlightstar4031 February 20, 2012 at 5:39 pm #

    can spatial summation be both inhibitory and excitatory?

  74. sunlightstar4031 February 20, 2012 at 10:39 pm #

    can spatial summation be both inhibitory and excitatory?

  75. bdogs5750 March 3, 2012 at 8:38 pm #

    Excellent! Very helpful and easy to understand. Thank you!

  76. bdogs5750 March 4, 2012 at 1:38 am #

    Excellent! Very helpful and easy to understand. Thank you!

  77. aleskamk March 6, 2012 at 12:37 am #

    Great understandable video. Sometimes textbooks just don’t make sense and I have to go find other resources! =)

  78. aleskamk March 6, 2012 at 5:37 am #

    Great understandable video. Sometimes textbooks just don’t make sense and I have to go find other resources! =)

  79. 20019988 March 10, 2012 at 4:50 pm #

    thank u very much , ur vids r very helpful and clear God bless u

  80. 20019988 March 10, 2012 at 9:50 pm #

    thank u very much , ur vids r very helpful and clear God bless u

  81. RACHAEL ADE March 31, 2012 at 2:36 pm #

    Good job Leslie. Your video has really blessed me.

    Thanks and remain blessed.

  82. somaprincess April 7, 2012 at 2:42 am #

    everything is so clear thank you!!!

  83. somaprincess April 7, 2012 at 6:42 am #

    everything is so clear thank you!!!

  84. christine8767 May 17, 2012 at 11:18 am #

    i was so gonna fail my exam- i had it all wrong thank you very much for clarifying

  85. christine8767 May 17, 2012 at 11:18 am #

    i was so gonna fail my exam- i had it all wrong thank you very much for clarifying

  86. christine8767 May 17, 2012 at 11:18 am #

    i was so gonna fail my exam- i had it all wrong thank you very much for clarifying

  87. versatilevoices June 14, 2012 at 4:34 pm #

    you know how to explain…thanks for this video…it made things clearer…

  88. versatilevoices June 14, 2012 at 4:34 pm #

    you know how to explain…thanks for this video…it made things clearer…

  89. drtonyfernandez123 June 14, 2012 at 9:09 pm #

    thank you.

  90. drtonyfernandez123 June 14, 2012 at 9:09 pm #

    thank you.

  91. michaelEDWARDangel June 15, 2012 at 6:50 am #

    THANKS!!!!

  92. michaelEDWARDangel June 15, 2012 at 6:50 am #

    THANKS!!!!

  93. mjegan72 June 17, 2012 at 1:16 am #

    Leslie, Thank you so much for your videos. I have a very hard time with understanding how my professor explains things. You ALWAYS do such a great job of explaining things to where I understand it. You make it simple and interesting. Thank you, thank you, thank you! :) You are AWSOME!!

  94. mjegan72 June 17, 2012 at 1:16 am #

    Leslie, Thank you so much for your videos. I have a very hard time with understanding how my professor explains things. You ALWAYS do such a great job of explaining things to where I understand it. You make it simple and interesting. Thank you, thank you, thank you! :) You are AWSOME!!

  95. warri0rs11 June 17, 2012 at 12:17 pm #

    thx. great

  96. warri0rs11 June 17, 2012 at 12:17 pm #

    thx. great

  97. nataliegb9140 July 3, 2012 at 11:57 pm #

    You’re a life saver!!!

  98. nataliegb9140 July 3, 2012 at 11:57 pm #

    You’re a life saver!!!

  99. nataliegb9140 July 3, 2012 at 11:57 pm #

    You’re a life saver!!!

  100. praveena reddy July 8, 2012 at 11:22 am #

    This video really helped me…thank you so much…!!!!

  101. praveena reddy July 8, 2012 at 11:22 am #

    This video really helped me…thank you so much…!!!!

  102. praveena reddy July 8, 2012 at 11:22 am #

    This video really helped me…thank you so much…!!!!

  103. 178890905 July 18, 2012 at 3:16 am #

    u saved my life.

  104. 178890905 July 18, 2012 at 3:16 am #

    u saved my life.

  105. miss.v ee October 18, 2012 at 5:50 am #

    My gosh ..u are great! My teacher with a Ph.D couldnt even explain this :/

  106. zbrooo October 18, 2012 at 3:15 pm #

    I think with a small time constant the action potential in the neurone is over faster and therefore the frequency and therefore strength of the impulses must be much higher in order for temporal summation to occur. This means with a smaller time constant a greater stimulus must be required for the excitatory post synaptic potential to reach threshold.

  107. anilynh November 5, 2012 at 2:00 am #

    Thank you so much! I stared at my textbook for 30 minutes and was so very confused!

  108. Simon Boland November 14, 2012 at 1:47 pm #

    my balls hurt because of this video

  109. barissimo111 November 22, 2012 at 8:06 pm #

    well i did not find a german video of this topic so i searched an englisch one…awesome explanation could not be easier explained really thx

  110. joeaiello2 December 9, 2012 at 4:33 am #

    Fantastic description. Thank you

  111. artiosarri December 9, 2012 at 11:12 pm #

    My professor did not cover this subject in class however it is on the departmental final. Luckily i found your video, very clear and concise information. Just wanted to say thank you!

  112. patricia campos December 10, 2012 at 7:43 am #

    EXCELLENT!!!!!!!!!!! LOVED IT! made it much easier for me to understand. I have read this section on my textbook several times, but it didn’t make sense to me. Thank you so much! Continue with these great explanations, you make a difference in understanding and also in a grade for a paper ;)

  113. LastSparkle February 4, 2013 at 5:59 pm #

    thank you so much! you’ve probably saved me from a bad mark tomorrow. oh and – best wishes from germany :)

  114. hphs50 February 16, 2013 at 6:58 pm #

    Extremely helpful. Thank you!

  115. Jumana Altheeb March 9, 2013 at 6:27 pm #

    Very helpful !! made it much easier for me to understand. Thank you so much :)

  116. valalberti22 March 24, 2013 at 8:06 am #

    Thank youu. Totally understand now!

  117. Chloe Hess April 11, 2013 at 11:38 am #

    Thank you!!!! You made the information much more clear for me!

  118. skomura April 12, 2013 at 2:19 pm #

    I just wanted to thank you for sharing this video – I was lost until I saw this video!

  119. skomura April 12, 2013 at 2:19 pm #

    I just wanted to thank you for sharing this video – I was lost until I saw this video!

  120. Tamoto08 April 13, 2013 at 8:57 am #

    Thank you for your videos! They are very helpful to me and make Biology fun.

  121. daisytigler April 24, 2013 at 8:27 am #

    I just want to say your videos are SO so helpful. Im a vet student and wouldn’t be able to pass physiology without you!

  122. Tom T May 4, 2013 at 11:05 am #

    So great! Helped so much!

  123. mamaeesh May 12, 2013 at 7:53 pm #

    Your explanations are perfect- to the point, simple, easy to understand without a lot of unnecessary verbiage to confuse me. Great work! :-) If I get an A on my final, some of the credit goes to you!

  124. ringsanoj99 May 27, 2013 at 10:37 am #

    You sir are immensely awesome. Thank you very much! :)

  125. kostasaekara May 28, 2013 at 1:25 pm #

    hello i have a question. In order to produce an action potential whe have to reach the threshold. But the threshold is not a potential, its an intensity, mesured with amperes, not volts. Could you help me?

  126. kostasaekara May 28, 2013 at 1:25 pm #

    hello i have a question. In order to produce an action potential whe have to reach the threshold. But the threshold is not a potential, its an intensity, mesured with amperes, not volts. Could you help me?

  127. Desta Kinfe June 8, 2013 at 9:38 pm #

    wow now it is clear for me

  128. rainbowcookiie June 9, 2013 at 10:00 am #

    Awesome, thank you!

  129. Ray July 5, 2013 at 2:03 pm #

    AMAZING videos! I’ve been reading my textbook for hours without understanding any if it and you can make it so clear in 5 minutes!!!! You are amazingly gifted!!! Thank you for sharing your wonderful gifts with us lost souls :)))

  130. Rowella Bacwaden July 28, 2013 at 2:59 pm #

    Hello Leslie….this is great. Do you have discussions on the anatomy of the heart and lungs?

  131. nanadiivadoll September 3, 2013 at 5:34 am #

    If temporal summation is a type of summation where a post synaptic neuron is stimulated by a repetitive firing of a single presynaptic neuron. Then what is spatial synaptic neuron? :)

  132. hitppohiman September 24, 2013 at 10:50 pm #

    you are legitimately the best

  133. Alex Kubik October 11, 2013 at 2:31 pm #

    Great video, Chap! Cheers from Australia!

  134. Glenda V. October 15, 2013 at 3:51 pm #

    you are soooo awesome!! you are helping a lot!!

  135. Glenda V. October 15, 2013 at 3:51 pm #

    you are soooo awesome!! you are helping a lot!!

  136. Putenschnitzel Sodla October 22, 2013 at 9:28 am #

    hi, I’m from Germany. I used your video to understand this topic due to there are no good german videos…. You speak a understandable English and you present the topic understandable…… greetings from Bavaria :)

  137. Putenschnitzel Sodla October 22, 2013 at 9:28 am #

    hi, I’m from Germany. I used your video to understand this topic due to there are no good german videos…. You speak a understandable English and you present the topic understandable…… greetings from Bavaria :)

  138. smilebeautifulworld October 26, 2013 at 1:48 pm #

    There’s potential called threshold potential (-55mV) when reached affects certain voltage gated Na+ that when opened give rise for rapid change in membrane potential due to entering of sodium into the cell.

  139. smilebeautifulworld October 26, 2013 at 1:49 pm #

    Na+ channels I meant

  140. Klo M October 26, 2013 at 9:25 pm #

    Thank you!

  141. Motaz Aldbass November 5, 2013 at 7:05 am #

    thanks a lot that was real helpful

  142. Shokou B November 12, 2013 at 1:12 am #

    Wow amazing

  143. Mutuma Kimaita November 19, 2013 at 4:01 am #

    this video is awesome. your explanations are clear and precise. keep up the
    good job.

  144. Robert Edwards Jr March 10, 2014 at 11:52 am #

    Summation that results from the multiple synapses firing at nearly the same time is designated?