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043 The Details of Muscle Contraction

Join Leslie as he shares this last video on muscle contraction explaining with full clarity the smallest details on how this works.

Enjoy!

Transcript of Today’s Episode

Hello and welcome to another episode of Interactive Biology TV where we’re making Biology fun! My name is Leslie Samuel and in this episode, Episode 43, I am going to go into the details of muscle contraction. This is going to be the last video in the muscle contraction series, so, enjoy! Let’s get right into it.

You can always go back to Episode 42 to refresh your memory but, we said that the functional unit of contraction is called the sarcomere and, that is what we’re looking at right now. This unit is one sarcomere. We said that we have a thick filament that is called myosin and, we have a thin filament that is called actin. We said that, when muscle contraction happens, the more the neuron releases neurotransmitter that stimulates calcium release. When that happens, the fibers slide against each other just like this. So, as the muscle fibers becomes shorter, that is the muscle contracting. And you can clearly see that in this animation.

The reason we said that this can happen is because on the myosin filaments, we have these heads and those heads extend and bind to the actin. When they bind, they kind of flex so, it moves in this direction and that pulls the actin shortening the sarcomere.

What we are going to do today is we’re going to look at the details of what is happening there. We are going to look at six steps in muscle contraction. This is another image that’s showing something similar to what we’ve looked at. We have the myosin heads. Let me do that in a different color so that you can make sure to see it because we have a lot of red there. We have the myosin heads that are binding to the actin filaments.

Here, we are going to be looking at that in more details. We have the actin. Yes, it’s a different spelling because it’s from a different language but, on the actin filaments, there are two things that are very important. We have tropomyosin as you see here so that’s this long strand here. On top of the tropomyosin, we have troponin. This is a complex that we find all along the actin filaments.

Here’s the situation. Because this is here, the myosin heads want to bind to the actin. There’s some binding sites on the actin so, let’s say this is a binding site right here. But, what’s the problem? The tropomyosin is covering that binding site so, the myosin heads cannot bind. Okay, so, we have these myosin head-binding sites all along the actin; myosin heads want to bind, we have all these myosin heads ready to do their business but, they cannot because it’s blocked by the tropomyosin.

All right so, let’s go now and look at the six steps of muscle contraction. Step number one. Calcium is released from the terminal cisternae. Remember we said that the terminal cisternae is a part of the sarcoplasmic reticulum and that is where calcium is stored. So, calcium is released. You can see here, we have this little binding site for the calcium so the calcium now comes and binds the troponin. So, here we have calcium and binding to the troponin. And then, what that does is it causes a conformational change. To put it more simply, we’re just moving the tropomyosin-troponin complex. So, that moves and, when that moves, it exposes the binding sites on the actin. That’s step number one. So, step number one: We had calcium in the terminal cisternae that is released when there’s a stimulus. The calcium ions bind to the troponin causing a conformational change in the troponin-tropomyosin complex. In other words, it’s moving out of the way. And then, the next step can happen. That step is, the myosin heads can bind to the binding sites on the actin. So, this is the one binding site. For simplification we’re just showing one myosin head but, as you know we have many myosin heads all along this actin.

In order for that to happen, we said that there’s normally ATP that’s on the myosin heads and you saw that, you saw that in the previous figure. But, that ATP has to be hydrolyzed to become ADP and an inorganic phosphate (Pi). So, we have ADP and the phosphate. All right, so, we have the myosin head that has bound to the binding site on the actin. That was step number two. Step number three. This ADP and Pi is released from the myosin head. I’m not showing that in the figure but, just imagine that being released. When that is released it causes the power stroke. In other words, it causes this guy here to flex. And when it flexes, it moves in this direction and that causes the actin to slide across the myosin.

Okay, so, calcium is released, step number one, binds to the troponin, causes this change in the troponin-tropomyosin complex so that it gets out of the way; ATP being hydrolyzed into ADP and inorganic phosphate is a state that this needs to be in for the myosin head to bind. When those are released, the myosin head flexes and we get the power stroke. That’s step number three.

Let’s go to step number four. Step number four is another one that I’m not showing but, we have ATP. So, this is an ATP molecule that comes in and binds to the myosin head. When that binds to the myosin head, the myosin head then detaches from the actin so, we no longer have that connection. That’s step number four.

Step number five. ATP is hydrolyzed which re-energizes the myosin head. So, once we have ATP being hydrolyzed like it is here, that re-energizes the myosin head and it’s ready to go again.

One more step, step number six. This calcium here needs to be gone. So, we have the terminal cisternae and it’s not shown here. So, I’m just going to draw it with my great artistic skills. We have calcium pumps in the terminal cisternae. What that does is it basically pumps that calcium back in. So, we have calcium being pumped back in that is going to cause the troponin-tropomyosin complex to go back to where it was and it’s going to be blocking… I should have done that in green to keep the consistency. Oh, I still can, why not. Okay, so we have the troponin-tropomyosin complex that is blocking once again the binding site for the myosin head.

All right, so let’s recap on that real quick. Step number one: Calcium is released, binds to the troponin. When it binds, it causes a conformational change or a shift, whichever one you want to call it, it causes that shift exposing the binding sites on the actin. Step number two: Myosin head binds to the actin. Remember that the ATP has to be hydrolyzed into ADP and Pi in order for that to take place, it has to be re-energized. It gets that from that hydrolysis process. Step number three: ADP and Pi release that causes power strokes that causes this guy to flex. Then, ATP comes in, binds to the myosin head, causes the myosin head to be released from the actin. The myosin head gets re-energized when the ATP is hydrolyzed back into ADP and Pi. Calcium ions are pumped back into the terminal cisternae and this process can happen again.

Well, that’s pretty much it. That is muscle contraction. If you have any questions, go ahead and leave them in the comments. That’s all for this video, and I’ll see you on 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

267 Responses to “043 The Details of Muscle Contraction”

  1. HD Choi April 6, 2011 at 9:26 am #

    This video is “Fabulous”.
    I’m a Univ. student in korea, and my proffesor can never make me and my friends understand.
    but this 10 mins video makes me understand!!!!
    You r the best

    ——a Student who loves Biology

    • Leslie April 6, 2011 at 10:09 am #

      That’s awesome. Glad you are enjoying the content and glad it is helping you to understand. Make sure to share it with all your classmates :)

  2. Leslie April 6, 2011 at 10:16 am #

    Just Testing!

  3. Tara Schlitz April 18, 2011 at 1:00 am #

    Dear Leslie, I am 44 years old and going back to school to become a Nurse. I have to upgrade my Biology. I have been struggling with studying. I stumbled onto one of your videos on You Tube when I was searching for information on Na+/K+pump. I found myself on your site watching many of your lectures. I would like to thank you for making it fun, interesting, and easy to understand. I have learned so much from just watching and listening to you.
    Deepest Thanks, Sincerely, Tara

    • Leslie April 18, 2011 at 7:34 am #

      Hi Tara,

      You are very much welcome. I’m soooo glad that you have found the videos to be helpful, and fun. That’s my goal. I know that it can be complicated studying from the textbook, so I want to do whatever I can to help. You can help me by sharing it with your classmates, and even professors.

      All the best with your program, and check back often because we’ll be doing some awesome stuff in the near future :)

      Leslie

  4. Maurizio April 25, 2011 at 6:57 am #

    Hi, I’m from Italy, I am studying physiology and your videos are helping me so much. Thanking you is just not enough! You are really skilled in teaching.

    Hope I didn’t make bad grammar mistakes!

    • Lrsamuel April 25, 2011 at 4:58 pm #

      That’s great. Glad to know that you received a lot of value in the videos. Don’t worry about grammar – I make mistakes with that all the time :)

  5. Imran May 30, 2011 at 7:24 am #

    It would be useful if there was something describing the difference between fast twitch and slow twitch fibres in terms of structure ect.
    But very well explained!

    • Lrsamuel May 30, 2011 at 9:00 am #

      That’s a good topic to cover in a video when I come back to the muscular system. Here’s a good introductory article on Fast and Twitch Muscle fibers. Hope that helps. Otherwise, you can always do a google search on the topic.

      • Imran May 30, 2011 at 9:12 am #

        Thank you. It would be great if you could cover that in a video.
        I love this video by the way!

        • Lrsamuel May 30, 2011 at 9:22 am #

          Thank you for your feedback Imran. Glad to know that you love the video. Those comments motivate me to make more :D

  6. Vickey June 15, 2011 at 3:04 pm #

    I was totally confused about this after my anatomy class…then I watched your video a couple of times and can not only understand what is happening but explain it to others…hope I do well on my exam tomorrow!! Thank you so much!

    • Lrsamuel June 15, 2011 at 3:14 pm #

      Vickey, that’s SO AWESOME. Glad to hear that. Every time I get a message like that it motivates me to do more. All the best on your exam tomorrow. Make sure to come back and let me know how it went.

  7. Estrellita Calaro June 29, 2011 at 1:15 am #

    Hi Leslie,

    Please bear with me. I really like to understand how neuron cells send signals to different types of muscles. Lets say, there is an excess extracellular calcium, how is this going to affect the contraction of the skeletal muscle cell? How about the smooth muscles like the intestines? Does it have the same effect like in cardiac muscle cells?

    Thanks a lot.

    • Lrsamuel June 29, 2011 at 9:10 am #

      Not a problem. Feel free to ask your questions. I assume that the effect is the same. However, I haven’t studied that in depth so I cannot guarantee that it’s definitely that way. You’d have to do more research on the subject.

  8. Djalitana September 3, 2011 at 7:38 am #

    great video. thanks. tell me during a muscle ATP converts to ADP only once or many times? I actually need to watch your vid about ATP and ADP. need to know what happens there and how they brake done and build up. Is awesome and your voice and your english is excellent and clear.

  9. Bas September 7, 2011 at 7:02 pm #

    Hello Leslie, I have some questions, what happens when a muscle get tired?

    Why does i hurt when you over excersize.

    How does “lactic acid” fit in to the picture.

    You do a great job in explaning how a human works, i never learned so much in so short amount of time. Bas.

    • Lrsamuel September 7, 2011 at 7:06 pm #

      Hi Bas,
      Glad to know you are learning so much. To answer your questions . . .
      Muscles get tired because they run out of the stuff they need (ATP, O2)
      It hurts because your muscle fibers actually tear. They tear and are rebuilt bigger and stronger over time.
      Lactic acid is produced during anaerobic respiration as a byproduct. That also causes some of the burning that you feel.
      Hope that helps.

  10. Bas September 7, 2011 at 7:08 pm #

    Hello, I forget to ask an other question.

    What is the difference between a hart muscle (get never tired)
    and a normal muscle?

    Bas.

  11. Lrsamuel September 7, 2011 at 7:11 pm #

    Different structure, doesn’t work as hard as when you are exercising hard. Your questions are too detailed to answer in a simple comment. Sorry that I can’t go into too much detail in the comments. Too much to do, too little time.

  12. ey7681 September 8, 2011 at 4:19 pm #

    wow!! im obsessed with your videos!! u explain everything so well!!thank u!!!

  13. InteractiveBiology September 8, 2011 at 8:53 pm #

    @ey7681 That’s awesome. Glad to know you are getting value in the videos :D

  14. REA0321 September 29, 2011 at 10:53 pm #

    Awesome videos !!! One of the best videos I have ever seen.

  15. InteractiveBiology September 30, 2011 at 8:19 am #

    @REA0321 Thank you very much! Stay tuned for more!

  16. ruddergrl1 October 2, 2011 at 10:15 pm #

    I can’t tell you how much you are helping me w/ my physiology class. My professor does not teach it well at all and doesn’t realize that he is ineffective. You make me feel like my goal is attainable. Don’t ever feel like you don’t make a difference…….

  17. InteractiveBiology October 3, 2011 at 5:57 am #

    @ruddergrl1 Glad to be able to help. All the best in your class.

  18. darktrool October 3, 2011 at 10:30 pm #

    I LOVE YOUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU MY HEROOO <3

  19. InteractiveBiology October 3, 2011 at 10:31 pm #

    @darktrool LOL. Thank ya :)

  20. MayokoLove October 8, 2011 at 11:04 pm #

    You sir…are my hero! :D <3

  21. InteractiveBiology October 9, 2011 at 10:08 am #

    @MayokoLove Nahhh, lol. Glad it’s helping though!

  22. 369thegoose1 October 16, 2011 at 9:33 am #

    You are incredible! Thank you so much…It makes so much sense…… I love you.

  23. InteractiveBiology October 16, 2011 at 9:34 am #

    @369thegoose1 Awww, thanks for the feedback, and for the love :)

    Stay tuned for many more!

  24. 369thegoose1 October 16, 2011 at 2:43 pm #

    Hi…may I ask a question ….. so is it true that the myosin myofilaments do not move and the actin myofilaments move by sliding on the myosin myofilaments? Thanks, I hope I hear from you real soon….
    Thanks :)

  25. 369thegoose1 October 16, 2011 at 2:43 pm #

    Hi…may I ask a question ….. so is it true that the myosin myofilaments do not move and the actin myofilaments move by sliding on the myosin myofilaments? Thanks, I hope I hear from you real soon….
    Thanks :)

  26. InteractiveBiology October 16, 2011 at 10:22 pm #

    @369thegoose1 All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions.

    All the best

  27. InteractiveBiology October 16, 2011 at 10:22 pm #

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

    All the best

  28. mo0odina November 8, 2011 at 7:03 am #

    you R the maaaaaan ! i swear U R greaaaaaat

  29. mo0odina November 8, 2011 at 7:03 am #

    you R the maaaaaan ! i swear U R greaaaaaat

  30. InteractiveBiology November 8, 2011 at 3:23 pm #

    @mo0odina Thank you! :) Stay tuned for more Biology videos coming very soon!

  31. InteractiveBiology November 8, 2011 at 3:23 pm #

    Thank you! :) Stay tuned for more Biology videos coming very soon!

  32. anfro18 November 10, 2011 at 1:17 pm #

    gonna go kill an anatomy and physiology midterm because of this!
    Thanks, subbed and am recommending to all my classmates

  33. InteractiveBiology November 10, 2011 at 1:25 pm #

    @anfro18 THANK YOU! We appreciate you spreading the news to everyone :) Good luck with your midterms!

  34. InteractiveBiology November 10, 2011 at 1:25 pm #

    THANK YOU! We appreciate you spreading the news to everyone :) Good luck with your midterms!

  35. anfro18 November 11, 2011 at 9:26 am #

    @InteractiveBiology This, quite literally, saved me on the midterm on 4 different questions.
    Thanks yet again!

  36. anfro18 November 11, 2011 at 9:26 am #

    This, quite literally, saved me on the midterm on 4 different questions.
    Thanks yet again!

  37. InteractiveBiology November 11, 2011 at 10:14 am #

    @anfro18 Wow! That’s fantastic! :) Stay tuned for more because we have a lot more coming :)

  38. InteractiveBiology November 11, 2011 at 10:14 am #

    Wow! That’s fantastic! :) Stay tuned for more because we have a lot more coming :)

  39. baby3194 December 7, 2011 at 11:51 pm #

    You just saved my life. I was the only one in Anatomy who was totally confused. You are amazing. Thank you!!

  40. InteractiveBiology December 8, 2011 at 3:23 pm #

    @baby3194 YOu’re welcome! Keep on watching to learn more :) Have fun with all our Biology videos!

  41. InteractiveBiology December 8, 2011 at 3:23 pm #

    YOu’re welcome! Keep on watching to learn more :) Have fun with all our Biology videos!

  42. rcamma December 28, 2011 at 5:12 am #

    i like your videos, can you nexplain it in german ;-)

  43. rickihicky January 2, 2012 at 8:28 am #

    Thankyou, very helpful

  44. inbalhof January 5, 2012 at 9:27 am #

    thank you very much!
    do you have lectures for a cardiac and smooth muscles?

  45. youngLeemac January 6, 2012 at 9:54 am #

    I don’t know self how to thank you, coz these sequence of events of contractile process in skeletal muscle #excitation-contraction coupling of your’s helped me alot. Thanks very much!

  46. hannansabah January 17, 2012 at 9:46 pm #

    My Allah bless you bro.

  47. researcherks12074 February 8, 2012 at 2:14 am #

    Thank you so much..its really fun to learn.

  48. RandomCrazyFella February 15, 2012 at 2:38 am #

    you are amazing .Thank you so much !!!

  49. Anne-Marie February 19, 2012 at 8:29 pm #

    Leslie…you are gold!
    I have just found your website and simply could not wait to tell my lecturers/student body about you!You have made my study a pleasure and I look forward to more of your work. From the bottom of my heart THANK-YOU!
    From Australia with Gratitude!
    Anne-Marie

    • Leslie Samuel February 21, 2012 at 10:50 pm #

      Well thank you very much Anne-Marie,

      I’m trying to do my best to provide the best resources I possibly can. Stay tuned for more, because I have lots coming!

  50. tanha6566 February 22, 2012 at 7:27 pm #

    dats really a very good explaination………I got everything very clear now…….thank you very much

  51. tanha6566 February 22, 2012 at 7:27 pm #

    dats really a very good explaination………I got everything very clear now…….thank you very much

  52. tanha6566 February 23, 2012 at 12:27 am #

    dats really a very good explaination………I got everything very clear now…….thank you very much

  53. gorgeouslady14 March 5, 2012 at 1:23 pm #

    What about the Mg++ that is responsible for the Ca++ to go back the Terminal Cisternae? Otherwise, this video is very very very helpful. Thanks

  54. gorgeouslady14 March 5, 2012 at 6:23 pm #

    What about the Mg++ that is responsible for the Ca++ to go back the Terminal Cisternae? Otherwise, this video is very very very helpful. Thanks

  55. rriggs2 March 16, 2012 at 10:53 pm #

    Huge Fan!!! I’ve been using your videos to help me get through the start of my doctoral degree in Physical Therapy – MUCH THANKS!!!

  56. rriggs2 March 17, 2012 at 2:53 am #

    Huge Fan!!! I’ve been using your videos to help me get through the start of my doctoral degree in Physical Therapy – MUCH THANKS!!!

  57. morboris March 21, 2012 at 2:59 am #

    when i first heard you say make biology fun i thought that this would be crap
    but you really did make it fun and understandable

  58. morboris March 21, 2012 at 6:59 am #

    when i first heard you say make biology fun i thought that this would be crap
    but you really did make it fun and understandable

  59. kickinbrass08 March 23, 2012 at 8:42 am #

    I think my university may as well forward my tuition fees to you…please keep it up!

  60. kickinbrass08 March 23, 2012 at 12:42 pm #

    I think my university may as well forward my tuition fees to you…please keep it up!

  61. 7StepzUnderTheSun March 23, 2012 at 3:05 pm #

    Thanx a million!

  62. 7StepzUnderTheSun March 23, 2012 at 3:07 pm #

    If all uni doctors and professors would explain stuff like you do, I would have NEVER skipped a class!

  63. 7StepzUnderTheSun March 23, 2012 at 7:05 pm #

    Thanx a million!

  64. 7StepzUnderTheSun March 23, 2012 at 7:07 pm #

    If all uni doctors and professors would explain stuff like you do, I would have NEVER skipped a class!

  65. ttithy March 25, 2012 at 10:26 pm #

    Wow, that was the best!!! A++++++++++

  66. ttithy March 26, 2012 at 2:26 am #

    Wow, that was the best!!! A++++++++++

  67. inamuchangel March 27, 2012 at 4:32 pm #

    thank you, was Magnesiun used to relax the muscle.

  68. inamuchangel March 27, 2012 at 4:32 pm #

    thank you, was Magnesiun used to relax the muscle.

  69. inamuchangel March 27, 2012 at 8:32 pm #

    thank you, was Magnesiun used to relax the muscle.

  70. AznMilu April 6, 2012 at 4:03 am #

    why is this so much different than my textbook? i dont know which to study, but yours is more clear and specific. thanks and nice job!

  71. AznMilu April 6, 2012 at 8:03 am #

    why is this so much different than my textbook? i dont know which to study, but yours is more clear and specific. thanks and nice job!

  72. hensonc4098 April 13, 2012 at 4:01 pm #

    I love how you go over everything a few times to help learn it, and that it’s easy to understand. This has been great to help me learn and understand muscle contraction as in the lectures, they will only explain really once or twice and are sometimes more difficult to understand. Thanks a lot!

  73. hensonc4098 April 13, 2012 at 8:01 pm #

    I love how you go over everything a few times to help learn it, and that it’s easy to understand. This has been great to help me learn and understand muscle contraction as in the lectures, they will only explain really once or twice and are sometimes more difficult to understand. Thanks a lot!

  74. shyeeyore April 14, 2012 at 5:56 pm #

    I wish you were my professor.. Some of these professors are just not good at teaching.

  75. shyeeyore April 14, 2012 at 9:56 pm #

    I wish you were my professor.. Some of these professors are just not good at teaching.

  76. uludrika April 17, 2012 at 4:47 pm #

    Very simple to understand thankyou!

  77. uludrika April 17, 2012 at 8:47 pm #

    Very simple to understand thankyou!

  78. STiCKGGY April 27, 2012 at 3:07 am #

    As a second year university student this video has really helped me, thanks a lot !

  79. STiCKGGY April 27, 2012 at 7:07 am #

    As a second year university student this video has really helped me, thanks a lot !

  80. satric75 May 1, 2012 at 6:00 pm #

    What’s the purpose of troponin causing a wall between myosin and actin.

  81. satric75 May 1, 2012 at 6:00 pm #

    What’s the purpose of troponin causing a wall between myosin and actin.

  82. Larkanaking1 May 2, 2012 at 7:38 am #

    this was very diff topic i fully understand

  83. Larkanaking1 May 2, 2012 at 7:38 am #

    this was very diff topic i fully understand

  84. Larkanaking1 May 2, 2012 at 7:38 am #

    this was very diff topic i fully understand

  85. Larkanaking1 May 2, 2012 at 7:38 am #

    by watching these videos

  86. Larkanaking1 May 2, 2012 at 7:38 am #

    by watching these videos

  87. MrEugenexYew May 7, 2012 at 1:06 pm #

    so that your muscles don’t contract all the time?

  88. MrEugenexYew May 7, 2012 at 1:06 pm #

    so that your muscles don’t contract all the time?

  89. satric75 May 7, 2012 at 1:46 pm #

    Thanks.

  90. satric75 May 7, 2012 at 1:46 pm #

    Thanks.

  91. qngo1 May 12, 2012 at 2:20 pm #

    Your videos are very helpful. Thank you for contributing such great videos. I am med student and there are some great points that I am picking up from your videos. Thank you.

  92. qngo1 May 12, 2012 at 2:20 pm #

    Your videos are very helpful. Thank you for contributing such great videos. I am med student and there are some great points that I am picking up from your videos. Thank you.

  93. Eamyeddi May 18, 2012 at 4:57 pm #

    I appreciate your videos verry much and iam really intereasted on them.Iam astudent iam studying pharmacy.ihope that you will make videos about renal physiology and endocrinology if you can .thankfuland iam soo

  94. Eamyeddi May 18, 2012 at 4:57 pm #

    I appreciate your videos verry much and iam really intereasted on them.Iam astudent iam studying pharmacy.ihope that you will make videos about renal physiology and endocrinology if you can .thankfuland iam soo

  95. AcousticMadnessMusic June 21, 2012 at 12:55 am #

    What about the acetocholinase? that assists in the process of removing calcium and resituating the muscle fibrile in its relaxed state by eating up the inorganics leftover? I’m sure you know what I’m talking about. Or, by all means correct me if I am wrong. Great info though. You really can explain it in a way that fits A to B to C….etc. Thanks.

  96. AcousticMadnessMusic June 21, 2012 at 12:55 am #

    What about the acetocholinase? that assists in the process of removing calcium and resituating the muscle fibrile in its relaxed state by eating up the inorganics leftover? I’m sure you know what I’m talking about. Or, by all means correct me if I am wrong. Great info though. You really can explain it in a way that fits A to B to C….etc. Thanks.

  97. AcousticMadnessMusic June 21, 2012 at 12:57 am #

    acetylcholinesterase ….that is the correct spelling. DAMN this A&P crap is so TECHNICAL!!!

  98. AcousticMadnessMusic June 21, 2012 at 12:57 am #

    acetylcholinesterase ….that is the correct spelling. DAMN this A&P crap is so TECHNICAL!!!

  99. minho gul July 11, 2012 at 5:34 pm #

    i am having hard time in biochemistry also can u guys plz upload lecture on biochem??

  100. minho gul July 11, 2012 at 5:34 pm #

    i am having hard time in biochemistry also can u guys plz upload lecture on biochem??

  101. minho gul July 11, 2012 at 6:15 pm #

    ya he is life saver thank yu :)

  102. minho gul July 11, 2012 at 6:15 pm #

    ya he is life saver thank yu :)

  103. Ayesha080987 August 4, 2012 at 6:19 pm #

    Thanks for making “Muscle Contraction topic” interesting and more importantly understandable

  104. Phenphinan Yarnkai August 7, 2012 at 2:19 pm #

    Thankss ~~ !! :))

  105. Carsono5 August 12, 2012 at 10:08 am #

    This was great – thank you!

  106. avasak123 August 13, 2012 at 2:26 am #

    Hi, have you wondered this method called the Max Muscle Method? (look for it on google). My sister says it gets people stronger.

  107. adrp100 August 24, 2012 at 3:39 pm #

    Very good video.can you explain the increased cross myocyte diameter during contraction? thanks

  108. sushmita majumdar August 27, 2012 at 8:45 am #

    keep uploading —for pathology ,pharmacology and microbiology !!!! will be of great help :D

  109. Lucy Lopez September 7, 2012 at 12:25 am #

    Reeally excellent video! Thank you, thank you very muchh!!

  110. CheshireCat88 September 17, 2012 at 1:22 am #

    That was great! Thank you for such an awesome and easy to understand explanation:)

  111. gressertobi September 24, 2012 at 4:35 pm #

    german image?

  112. kpdg027 September 30, 2012 at 11:58 pm #

    Thanks so much! Very helpful :)

  113. raraland1 October 4, 2012 at 1:25 pm #

    thankyou so much!

  114. aleharfouche October 4, 2012 at 2:30 pm #

    Awesome!!

  115. Matthew Alpert October 9, 2012 at 3:51 am #

    What program are you using for this video?

  116. tmpEngine October 9, 2012 at 9:43 am #

    In 9 minutes you just did what my teacher was trying to do for over 3 months ! You explained the whole thing, and.. wouah !! I finally got it !! Thank youuuuuu

  117. Squidbillyify October 10, 2012 at 2:25 am #

    So much more clearer than bio 223 teacher. I actually understand it now.

  118. ILMBWAMH October 14, 2012 at 5:22 pm #

    Thank you so much!

  119. iSina93 October 15, 2012 at 12:42 am #

    I go to UCLA. Youtube has taught me most of what I need to know

  120. langseth1410 October 18, 2012 at 12:40 am #

    do you have any videos on smooth muscle contraction? This one is on skeletal muscle but I need the one with MLCK and MLC and calmodulin

  121. detox96 October 18, 2012 at 1:02 am #

    I enjoyed your video. My instructor provided our class with 12 steps and our textbook has different steps as well. Though, I am starting to understand it. I would like to email you the 12 steps instead of posting them on youtube. to confirm they are correct. Could you please provide an email. Thanks

  122. Sarah Angelica Dallas October 20, 2012 at 1:45 pm #

    YOU are a LIFESAVER. Thank you so much!!! My professor isn’t the most helpful!

  123. kvietimas October 28, 2012 at 12:43 am #

    The greatest video ever when it comes to mind numbing muscle contraction. It just proves the power of good teaching. There are no dumb students, there are teachers who unable to explain. Cheerrrrs! I am so happy now :)

  124. Samar A.T October 29, 2012 at 6:49 pm #

    These videos are life-saving. I’m a pharmacy intern but my mind is all blank when it comes to physiology, biology and anatomy. So, THANK YOU SO MUCH!

  125. Rotiking October 30, 2012 at 7:20 pm #

    We need teachers like you Professor! THANK YOU and God bless!!!

  126. cornbreadfriedchkn October 31, 2012 at 9:47 pm #

    Excellent!!! Thank you so much for the explanation!

  127. Leah Olson November 2, 2012 at 11:46 pm #

    This is such a helpful video! Very clear, concise explanation which brought these concepts to life for me. Thank you! Looking forward to watching more of your Biology videos. Feeling much more confident for my anatomy midterm coming up. :)

  128. supertrinizim November 5, 2012 at 10:46 pm #

    am here because of my STRUCTURE AND FUNCTION CLASS in COSTAATT….excellent video!

  129. Bethany Hanrahan November 6, 2012 at 4:42 am #

    thank you so much your videos saved my life for this test!!

  130. aloap0907 November 6, 2012 at 11:34 am #

    @wlzbaqs yes i mean it. before I started eating right it didn’t matter how much I exercised my abs were still jello. Listen to this The surprising part is my friend who is not doing much excercises, maintaining his six pack with this secret food items. you can watch out here –> bit.ly/Qk8H6D?=csepgi

  131. deannwia November 6, 2012 at 7:05 pm #

    I was hoping to hear more about the muscle contraction beginning from the axon terminal. With acetylcolene and sodium being released

  132. Yvonne November 8, 2012 at 5:38 pm #

    Thank you for this video and for all of your videos! You always break it down in a way that makes it clear to me. I did extremely well on my test!

  133. mrsramos777 November 10, 2012 at 1:14 am #

    Best YOUTUBE video explaining the function and structural components of a sarcomere in a myofibril. WHOOP – WHOOP, I’M GOING TO PASS MY A&P TEST WITH AN A+!!!! LOL

  134. mixermail November 11, 2012 at 6:32 am #

    THHHHHHANK you…Helped soooo much.

  135. Monica C November 19, 2012 at 2:26 am #

    Thank you. Bless your heart sir.

  136. pslovekatey November 20, 2012 at 1:08 am #

    wow this video really helped… thank you so much…

  137. Crisk68 November 25, 2012 at 1:44 am #

    I have read this section again, and again in my text. Until I saw your video, it didn’t make a much sense. Now it’s much more understandable. Thanks!

  138. wade2953 November 25, 2012 at 3:43 am #

    Thanks great video!!!!

  139. Paul Darlington November 27, 2012 at 2:01 am #

    Thank you so much, God bless you.

  140. nyloofarke December 1, 2012 at 12:17 pm #

    why should ATP be hydrolysed during d second step

  141. Manchii0908 December 3, 2012 at 1:28 am #

    I think it’s cos it gives it energy to move the myosin head but to keep to doing it needs more ATP?

  142. crazylolotte94 December 8, 2012 at 7:10 pm #

    The hydrolysis of ATP gives energy so that the myosin head can bind

  143. Clarice Poirier December 9, 2012 at 1:13 am #

    Hi,
    Thank you for your videos!
    I just have a question : How does Ca travel from the SR to the Troponin?

  144. Ryan Corkal December 10, 2012 at 5:37 am #

    A second year university physiology course I am in says ADP is released at the end of the power stroke?

  145. mattmank7 December 10, 2012 at 12:53 pm #

    Just make sure you are not confusing the action of the power stroke occurring in real time or if he is referring to when the action of power stroking is over

  146. drpink86 December 17, 2012 at 4:10 am #

    Greetings,

    My name is Fransuas and I am a medical student about to take USMLE step 1. First I would like to congratulate you on your great videos. You teach in an excellent way I wish my professors in collage would have teach like that and now I wouldn’t have doubts on the more complicated mechanisms. I use your videos when I have doubt or to refresh my memory. I wanted to ask you if you have a smooth muscle contraction video?(con. on next post)

  147. drpink86 December 17, 2012 at 4:10 am #

    I just saw the skeletal muscle contraction video and is excellent. As you know the smooth muscle is different with the Ca- calmodulin and other things that I get mixed all the time. If you have it can you send me the link? Because I can’t find it. Thank you very much I really appreciate it.
    Fransuas
    PS.
    Just in case I wrote to the email on the website also.

  148. brankonadal December 27, 2012 at 10:19 pm #

    In one muscle contraction only one ATP will be used… !

  149. an9593 December 30, 2012 at 3:33 am #

    i seriously love you… thank you so much for this amazing video…. our teacher didn’t even teach us this and our exam is gonna cover this as well. so i thought i was pretty much screwed. but you literally saved my life….!!! again, thank you so much for uploading such an awesome video :)

  150. Matias Monteagudo December 30, 2012 at 4:10 am #

    Evolution is just amazing, at this level you realize how everything is chemistry in action.

  151. modernhippielife January 16, 2013 at 9:19 pm #

    What role does Mg ion play in the relaxing of muscles??

    I saw the notation for it in one of the pictures, but it wasn’t mentioned. I love your videos! I didn’t understand this by just reading my anatomy book- very helpful!!!

  152. vijaykumar goli January 17, 2013 at 5:01 pm #

    VERY NICE SIR,THANK FOR U R WONDERFUL PRESENTATION

  153. Kristoff Foster January 21, 2013 at 2:39 am #

    our country needs to invest in these kinds of videos that help students learn and understand concepts
    if I had money i’d donate.
    Brilliant.

  154. franco casal January 27, 2013 at 11:15 am #

    @unkiazs sure is right. before I started eating right it didn’t matter how much I exercised my abs were still jello. Listen In a best female model 2012 exclusive interview she had mentioned about her strong abs with this 7 food items. have a look here -> bit.ly/XE2Be0?=txhlbb

  155. Wal Sid January 29, 2013 at 11:08 pm #

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  156. dplopez6 February 11, 2013 at 6:59 am #

    Awesome video!

  157. DR.Leelamohan P.V.R. February 16, 2013 at 1:42 pm #

    awesome great explaination

  158. buckshotat February 18, 2013 at 4:24 pm #

    anybody else hear the pope from bob and tom?

  159. sharonshim11 February 19, 2013 at 2:14 pm #

    Wow. Amazing

  160. Virginia Cabrera Oliphant February 21, 2013 at 7:08 am #

    AMAZING!!!!!!!!!!!!!!!!

  161. jtf94259 March 17, 2013 at 8:13 pm #

    Excellent explanation!! I’m British and your accent makes everything so much more interesting!!!

  162. Ana Ceci Ot March 17, 2013 at 10:23 pm #

    It was actually fun! Thank you very much!

  163. jjday7 March 18, 2013 at 1:48 pm #

    This is so much easier to understand than a book. Thanks

  164. ymes2 March 19, 2013 at 5:06 am #

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  165. branubabygirl3x3 March 20, 2013 at 7:26 pm #

    OMG! Thank you soooo much for explaining this! My instructor made this process hard to comprehend. Learning it from a book on your own is so one-dimensional. Thank you for explaining this so I could understand it! I will be visiting the interactive site as well.

  166. branubabygirl3x3 March 20, 2013 at 7:26 pm #

    OMG! Thank you soooo much for explaining this! My instructor made this process hard to comprehend. Learning it from a book on your own is so one-dimensional. Thank you for explaining this so I could understand it! I will be visiting the interactive site as well.

  167. babigrlpink March 24, 2013 at 9:42 pm #

    You’re awesome!! Thank you for making these helpful videos!

  168. Tara Keo March 26, 2013 at 10:55 am #

    Thank you very much for making this video……it truly helps me….

  169. angelit161 March 27, 2013 at 7:28 pm #

    Thanks this helped me understand a little more

  170. sxyngel March 27, 2013 at 7:30 pm #

    where does the magnesium come from and what does it do

  171. Kristin Henriksen March 28, 2013 at 3:24 pm #

    That was totally helpful, I finally get it. Thank you.

  172. rajan sigdel March 30, 2013 at 3:48 am #

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  173. Lupa Day March 30, 2013 at 8:46 pm #

    Elated I found this film. Youtube is perfect for this kind of content.

    My step brother was formerly bullied. He said he was going to get bigger. I laughed… Then in just weeks he gained 40lbs of genuine muscle mass. He made use of the Muscle Building Bible (look in Google). No-one dares to intimidate the man anymore. :-) I subscribed the other day. See exactly what goes on. Not to mention this mans emails are fucking excellent…

  174. miski April 1, 2013 at 1:21 pm #

    thank you so much for posting these.thery are really helping me with my biology a level

  175. Nicole Schinzder April 2, 2013 at 1:50 pm #

    whew. What a relieve. Thanks so much. I love the way you go over those steps before you start a brand new step. Love it. Thanks for posting

  176. vanranzow1 April 4, 2013 at 11:40 am #

    In Step 4 where does the ATP that binds to Myosin come from?

  177. Michael Green April 4, 2013 at 5:21 pm #

    My class average on my A&P exam was a 65, I watched these videos and got a 93, i love you good sir, thank you!

  178. Kate Ricciardi April 5, 2013 at 10:58 am #

    Read 25 pages of my A&P book had no idea what they were flapping on about… thank you so much for making this so simple!!
    great teaching!!

  179. pinkfloyd1589 April 7, 2013 at 7:03 pm #

    does the myosin have to move the whole way across the actin? or is it some kind of graded response where the myosin can also move halfway if it likes?

  180. Jaspii1 April 9, 2013 at 3:17 am #

    Do you have a lisp??

  181. 29erteamAUT1536 April 9, 2013 at 2:13 pm #

    sure is right. even i was very sad since i workout well for abs but nothing was coming. Listen to this I saw an interview with body building champion where he talks about 7 odd foods he eats to keep his abs hard. get to know here -> bit.ly/10OySTl?=ubgor

  182. 29erteamAUT1536 April 9, 2013 at 2:13 pm #

    sure is right. even i was very sad since i workout well for abs but nothing was coming. Listen to this I saw an interview with body building champion where he talks about 7 odd foods he eats to keep his abs hard. get to know here -> bit.ly/10OySTl?=ubgor

  183. 627funny April 10, 2013 at 7:57 pm #

    The sliding of the actin over the myosin is incremental; in order for the two actin molecules to become so close, the actin-myosin reaction has to happen multiple times. The muscle can pull the actin as close to each other as it wants, as long as there is calcium and ATP to power each slide.

    TL;DR it can be a graded response

  184. 627funny April 10, 2013 at 8:05 pm #

    If you’re asking immediately where it comes from at that instant, it is brought from mitochondria which are plentiful in muscle cells.

    More specifically, within the mitochondria, the Citric Acid Cycle is used to convert the energy in glucose into smaller, more usable units of energy stored in ATP. The Citric Acid Cycle produces NADH and FADH2 which carry electrons to the Electron Transport Chain, which in turn produce ATP using ATPase in the mitochondrion. Search Google for more details.

  185. pinkfloyd1589 April 11, 2013 at 8:04 am #

    thanks for the reply, sorry to be annoying but to clarify, so this sliding filament mechanism as well as the motor unit concept are both used in conjunction to give a graded response? would it be right to say that since increased action potentials stimulates more motor units?

  186. supertrain21 April 11, 2013 at 11:33 am #

    Why can not you be my Physiology professor?? lol Thanks anyways

  187. TehPwninator1 April 11, 2013 at 1:16 pm #

    I think videos like this are the future of teaching, it’s just so much more effective than a textbook or teaching on a chalk board. You’re also a very talented teacher, thank you for making this.

  188. TehPwninator1 April 11, 2013 at 1:16 pm #

    I think videos like this are the future of teaching, it’s just so much more effective than a textbook or teaching on a chalk board. You’re also a very talented teacher, thank you for making this.

  189. osmoregulator April 12, 2013 at 12:21 pm #

    Excellent video!

  190. Razzziiiiiiiiiiiiiii April 17, 2013 at 11:56 pm #

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  192. RoseRed12393 April 18, 2013 at 2:36 pm #

    Sir, you are truly amazing. Your videos have been incredibly helpful for me seeing the processes and applying the concepts and this video is no exception. Keep up the great work!

  193. AlmaSouthAfrica April 19, 2013 at 6:37 pm #

    Thank you! Amazing, you helped me so much today.

  194. Lora G April 22, 2013 at 2:44 pm #

    This has cleared it up! Thank you SO very much!

  195. Alessandra Dallera April 25, 2013 at 8:10 pm #

    THANK YOU !!!! you clarifyed so much !!!!

  196. LiveLoveLearnism April 29, 2013 at 7:58 pm #

    Thank you.. Your work is very much appreciated! Take care : )

  197. PineGremlins May 4, 2013 at 8:51 am #

    your accent makes learning so much more bearable, great stuff! and very selfless to put it up on-line free of charge!
    thanks a bundle

  198. zulhamakbar May 5, 2013 at 11:58 am #

    If you really want to get a six pack, you should take a look on Google for “Oak Muscle Method”. You are guaranteed to achieve the muscles you deserve.

  199. noclassmail May 7, 2013 at 7:36 pm #

    Thank you so much for this video! I have a final tomorrow and I finally understand what my professor attempted to explain!

  200. Nicole Schinzder May 9, 2013 at 8:26 pm #

    Where was your old six steps? Is there anyway I can still find it on your page ?

  201. Nicole Schinzder May 9, 2013 at 8:29 pm #

    Never mind . Found it

  202. Fabian Kr May 12, 2013 at 2:24 am #

    Thank you

  203. Dan Kent May 13, 2013 at 8:00 am #

    don’t know how people can’t like this!

  204. Akhila Abraham May 17, 2013 at 3:07 am #

    thanxxxxxxxxxxxxxxxx

  205. Ameen Ahmed May 18, 2013 at 5:47 pm #

    I love this guy’s accent! I feel like I’m learning a lot from him already!

  206. thachnamxanh May 20, 2013 at 5:19 pm #

    Thank you so much for making and sharing this video! It helps me a lot. You’ve a lovely voice!

  207. TheKamo72 June 1, 2013 at 2:51 pm #

    amazing video , :) thank you for uploading this !

  208. kwenzie June 1, 2013 at 4:06 pm #

    wow, wow, wow! you really make this simple and straight to the point….i have an exam in 3 days and i for once can say “im ready for the physiology paper”. thanks a lot you are really heaven sent to tutor me and GOD bless you

  209. feelinsabina June 3, 2013 at 5:24 pm #

    thank you! you explained it very well:)

  210. Frox4ever June 3, 2013 at 6:13 pm #

    Oh, shut up, Ameen!

  211. XXXbalenciaga June 7, 2013 at 3:12 am #

    This is just great!!! Thanks so much!

  212. Weston Stover June 9, 2013 at 12:53 pm #

    Step 1 can be expanded on a bit:
    - AP traveling down T-tubule activates (Dihydropyridine) L-type Ca channels causing Ca influx
    - Ca influx acts at Ryanodine Ca dependent Ca channels on the Sarcoplasmic reticulum causing the release of sarcoplasmic reticulum Ca stores.
    - Ca then can bind to troponin C, etc, etc ,etc

    Other than great video!

  213. Weston Stover June 9, 2013 at 12:53 pm #

    Step 1 can be expanded on a bit:
    - AP traveling down T-tubule activates (Dihydropyridine) L-type Ca channels causing Ca influx
    - Ca influx acts at Ryanodine Ca dependent Ca channels on the Sarcoplasmic reticulum causing the release of sarcoplasmic reticulum Ca stores.
    - Ca then can bind to troponin C, etc, etc ,etc

    Other than great video!

  214. Ameen Ahmed June 9, 2013 at 6:54 pm #

    The top comment is practically the same, yet my comment gets disliked. Sounds fair.

  215. visswaayful June 13, 2013 at 2:28 am #

    Thank you!!! I really enjoy your presentations,very thorough. I really get a clear understanding everytime I watch your tuts. Really appreciate it!!
    Tks : )

  216. Jeroen Rooman June 15, 2013 at 9:19 am #

    What is the funtion of Titine on muscle contraction?

  217. vroleinbau June 16, 2013 at 6:37 pm #

    This was very easy to understand. Thank you for the work you invested:)

  218. Julia Khestanova June 17, 2013 at 6:41 pm #

    THANK YOU!!! Instead of reading a boring 10 pages chapter (which takes me 2-3 hours to comprehend), I watch your 10 min video and understand everything! Very helpful especially if English is a second lang! ( I am Russian)

  219. rubenator6 June 20, 2013 at 1:15 am #

    yes I agree cant even believe it. i know the bad fat is the reason that stopping 6 pack coming outside even we work out well. Listen The surprising part is my friend who is not doing much excercises, maintaining his six pack with this secret food items. check it out here bit.ly/10zdh63?=jrekr

  220. Dana Jordan June 26, 2013 at 10:20 pm #

    Thank you so much for your time and energy. You have no idea how much this has helped me!

  221. Sani Sanusi July 3, 2013 at 7:15 pm #

    Thank you for your wonderful presentations. Please kindly make another video on action potential regarding Numbness ,when anaesthetic solution is injected at Axon terminal.

  222. Wom Bat July 10, 2013 at 5:15 pm #

    Extremely well done! Thank you, this is only video I’ve seen that has helped me understand.

  223. Rakesh Patel July 13, 2013 at 4:33 pm #

    you are correct. you can make your workout sessions much more productive if your eating the right foods to avoid fat and belly. Between In a best female model 2012 exclusive interview she had mentioned about her strong abs with this 7 food items. you can see it here bit.ly/17c5ASh?=pohpw

  224. Fred July 13, 2013 at 9:17 pm #

    The lessons on skeletal muscle contraction were excellent! The lecture and the book gave me enough information to confuse me, but your presentation brought it all home!!!!
    I now have you book-marked
    Thanks!

  225. divakar singh July 15, 2013 at 8:55 am #

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  226. respeezy July 23, 2013 at 6:36 am #

    Tx for the vid, haha the accent helps a lot its so much better to listen to than some other boring vids with monotone voices.

  227. Federico Dezi July 24, 2013 at 11:46 am #

    yes i mean it. you can make your workout sessions much more productive if your eating the right foods to avoid fat and belly. Listen to this In a best female model 2012 exclusive interview she had mentioned about her strong abs with this 7 food items. have a look here bit.ly/16ZDK9R?=zchmb

  228. Lucas Cocco August 5, 2013 at 1:33 am #

    Titin is a giant protein that functions as a molecular spring which is responsible for the passive elasticity of muscle.

  229. Arpie Haroutounian August 5, 2013 at 2:13 pm #

    Thank you, I’ve learned so much by watching your videos!

  230. Avik Mukherjee August 7, 2013 at 12:20 pm #

    yes I agree cant even believe it. i know the bad fat is the reason that stopping 6 pack coming outside even we work out well. But I saw an interview with body building champion where he talks about 7 odd foods he eats to keep his abs hard. if you are serious go for it now bit.ly/14jXzLt?=dmkty

  231. Patricia Caulline Mauricio August 11, 2013 at 9:08 am #

    THANK YOU! Because of you, I’ll be able to pass my quiz tomorrow.
    Great explanation. I more understand it. God bless you! :)

  232. yeyint thwe August 12, 2013 at 12:02 am #

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  233. angiii August 17, 2013 at 4:38 pm #

    thanku very much i:am a 10 class grader and really appeariciate,,, ur video it actually helped me a lott and to understand every single step in binding

  234. Ngoanapedi Komane August 23, 2013 at 3:59 am #

    u are the best***

  235. siddhipathlab August 23, 2013 at 7:09 am #

    Very nice video!! Understood very nicely thanks a lott!!:)

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  237. Enrika August 27, 2013 at 6:06 pm #

    Hi Leslie, thanks for great videos they are so easy to understand and informative. However I did missed one think in muscle contraction video, at school in the UK we been talk about the cross bridge, can you explain me which part of the contraction called cross bridge.
    Thank you!!

  238. ahmede yonus September 5, 2013 at 4:50 am #

    thank you mr InteractiveBiology

  239. Brian Fernandez September 5, 2013 at 11:05 pm #

    Thank you for making sense

  240. TheJamesPark September 10, 2013 at 10:38 pm #

    i have physiology right now and you sir saved me a whole bunch. REALLY love your videos. very simple to understand and enjoyable!!!!
    wish u were the professor…

  241. Amanda Ndessy September 13, 2013 at 5:45 am #

    Awesome, stay blessed :)

  242. sagala40 September 16, 2013 at 7:29 pm #

    Wow, you are a great teacher. Your voice, your animation, your simplicity, and the steps you go over and over makes it soooo simple to learn!!!! Awesome! :)))))

  243. khadija abdulla September 24, 2013 at 7:26 am #

    thank you very much

  244. Mark Anthony .Ramos September 25, 2013 at 6:37 pm #

    Is this the same process in heart cells???

  245. xtremeno natural muscle enhancer reviews September 27, 2013 at 2:35 pm #

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  246. princess nawraa September 28, 2013 at 3:18 am #

    I got it ~~~ thanks alot ~~~~

  247. hotsauce3n October 8, 2013 at 12:35 pm #

    Really good breakdown good job

  248. Light Yagami October 11, 2013 at 3:10 pm #

    Great Vid

  249. kwon young October 20, 2013 at 12:09 am #

    wow. he makes it so clear.from now on im going to watch all of his video

  250. Dave Seward October 20, 2013 at 12:23 pm #

    VERY helpful!!! I never would have got this concept without this video!!!

  251. Dave Seward October 20, 2013 at 12:23 pm #

    VERY helpful!!! I never would have got this concept without this video!!!

  252. Pablo Gonzalez October 23, 2013 at 1:46 am #

    Great teaching, I actually learned it, super simple!

  253. Fityan Guitarist October 25, 2013 at 2:27 am #

    Thanx pretty much

  254. phindy p October 26, 2013 at 7:44 pm #

    best explanation tnx

  255. Geraldine Molina October 28, 2013 at 3:01 pm #

    Very good… :-)

  256. MillieKayz Brown November 15, 2013 at 1:54 am #

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  257. Dinesh April 18, 2014 at 2:11 am #

    what is the role of that MG2+ ion shown in the picture