016 The release of Neurotransmitter

016 The release of Neurotransmitter

Leslie Samuel IBTV, The Nervous System 127 Comments

When the action potential reaches the axon terminals, something needs to happen in order to transfer that signal from one neuron to another.

Watch as Leslie explains the role of neurotransmitters and how their release results in a signal in other cells, organs, or glands.

Enjoy!

Transcript of Todays Episode

Hello and welcome to another episode of Interactive Biology TV, where we’re making biology fun! My name is Leslie Samuel. In this episode, Episode 16, I’m going to be talking about the neurotransmitter. We’ve been talking about the nervous system, we’ve been talking about neurons, and we’ve been talking about the action potential and how that travels along the neurons all the way to the ends of the neurons. What we’re going to do today is we’re going to focus a little more closely at the end of the neurons, the place that we call the axon terminal.

Now, neurons do not exist in isolation. They are interconnected, they connect to other neurons, as you can see right here. There’s a connection here, you can see there’s another connection here. Basically, when there’s a signal in one neuron, that can send a signal to many other neurons or glands or organs. This is the way the nervous system communicates, and there needs to be these connections, and signals need to go from one neuron to the next.

What I’m going to do is I’m going to zoom in on this connection here and we’re going to take a closer look at it. So we’re looking at that connection, and there are a few terms that you need to understand. The connection between the neurons, we call that the synapse. The synapse is the connection between one neuron and another neuron, or between one neuron and another cell, organ, or gland. We are basically talking about the place where neurons connect with other cells.

Another term that you need to know is the synaptic cleft, and the synaptic cleft is basically this space here that’s between the neurons. Most neurons don’t connect physically. There’s a small space between those neurons where they connect and there are some important things that are happening there, and we’re going to look at those things today.

Another term that you need to know would be the synaptic vesicles, and you can see there are a number of vesicles in here. What’s unique about these vesicles is that inside of those vesicles, we have neurotransmitters. You can see examples of neurotransmitters here. This is a neurotransmitter, and we have 3 in here, 2 in here, 1 in here. These are all neurotransmitters.

Another term that we need to be familiar with would be the receptor. The receptor is the protein or the part on the receiving cell that binds to the neurotransmitter. You can see a perfect example of one here.

Some other terminology that’s not on this image is, since we’re calling this the synapse, we have 2 membranes. We have this membrane here, and we have this membrane here. The membrane that comes right before the space, we call the pre-synaptic membrane. So that’s this membrane here. And the membrane that comes after the space, and that would be this membrane here, you guessed it! We call that the post-synaptic membrane. So those are the terms that I want you to be aware of as we go into talking about what happens when the action potential reaches the axon terminal.

We’ve spoken about the action potential, and the action potential travels along the axon. I want you to imagine with me an action potential coming down this axon and reaching the axon terminal. Now, there are a number of things that happen when the action potential reaches the axon terminal. One of the most important things that’s happening is we have voltage-gated calcium channels that open. When voltage-gated calcium channels open, calcium ions that are concentrated outside (I’m going to write Ca++) are going to rush into the cell.

This is a very important event because it causes something that’s very significant. It causes these synaptic vesicles to fuse with the pre-synaptic membrane, and you can see an example of that happening right here. When the synaptic vesicle fuses with the pre-synaptic membrane, that causes the neurotransmitter to be released into the synaptic cleft. You can see an example of a neurotransmitter that’s released right here, and of course, there’s another one right here.

Now, what then happens is also very important. The neurotransmitter binds to the receptor. When the neurotransmitter binds to the receptor, that can cause a signal in the receiving cell. So we can have a signal in this cell because neurotransmitters are being released and that binds to the receptors, and that causes a signal in the receiving cell.

This is how we can go from one neuron to the next neuron. Signals are travelling rapidly and they need to be routed to the right place. The way the neurons are going to communicate with each other is by this process of releasing neurotransmitters. That’s all the content for this video. If you have any questions about it or any comments, go ahead and leave a comment beneath this video in the comment field. I’d be happy to answer your question, or even make a follow-up video to answer your specific question. That’s all for this video, and I’ll see you in the next one.

Comments 127

  1. InteractiveBiology

    @Skoty6 That’s a great question. Yes, exocytosis is the process that is used to release the neurotransmitter from the axon terminal. This isn’t the only example of exocytosis, but it definitely is one.

    1. Amélie

      I’ve learned that during the proces of this specific exocytosis, a snare complex is formed. Could you please explain to me what a “snare complex” exactly is?

  2. InteractiveBiology

    @jmlevins1 In order to release the neurotransmitter, the vesicle actually fuses with membrane. Once it fuses with the membrane, that causes the content to be released, which in this case would be neurotransmitter.

  3. InteractiveBiology

    @jmlevins1 Yes, once the synaptic vesicle fuses with the membrane, it releases all its contents. However, all of the synaptic vesicles don’t necessarily fuse with the membrane to release Neurotransmitter. Some of them remain in the synaptic terminal. Hope that helps :)

  4. InteractiveBiology

    Yes, once the synaptic vesicle fuses with the membrane, it releases all its contents. However, all of the synaptic vesicles don’t necessarily fuse with the membrane to release Neurotransmitter. Some of them remain in the synaptic terminal. Hope that helps :)

  5. kpollock313

    I can’t believe how much your videos have helped! I could not make sense of any of this until I watched a few of your episodes! Thank you so much for taking the time to post these videos! I look forward to watching more!

  6. Kim Pollock

    I can’t believe how much your videos have helped! I could not make sense of
    any of this until I watched a few of your episodes! Thank you so much for
    taking the time to post these videos! I look forward to watching more!

    1. Post
      Author
      Leslie

      Hi Stephanie,

      It only takes 1 Action Potential in order for a neurotransmitter to be released, and that’s the same with Glutamate.

      All the best!

  7. Pingback: How the Release of Calcium Ions Results in Muscle Contraction – Episode 42 | Interactive Biology, by Leslie Samuel

  8. InteractiveBiology

    @megaloveistheanswer That’s so awesome. Glad the videos have helped you. Now go and get that A+ and make sure to come back and tell me about it :)

  9. markitot

    This video is very informational and explains all the details needed for any test related to the process of how the neuron works. Thanx

  10. diimtarsh1

    Hello, I liked your video, it explains things simply and clearly.I have a question though:
    When a signal traveling on the axon reaches the synapse a neurotransmitter is released.This can be let’s say dopamine or GABA or smth else, and is either inhibitory or excitatory, correct?Then the receiving neuron binds this neurotransmitter with its receptors and sends an electrical signal to the core of the cell, am I correct?The question is what kind of signal is this one – excitatory or inhibitory?10x

  11. diimtarsh1

    Hello, I liked your video, it explains things simply and clearly.I have a question though:
    When a signal traveling on the axon reaches the synapse a neurotransmitter is released.This can be let’s say dopamine or GABA or smth else, and is either inhibitory or excitatory, correct?Then the receiving neuron binds this neurotransmitter with its receptors and sends an electrical signal to the core of the cell, am I correct?The question is what kind of signal is this one – excitatory or inhibitory?10x

  12. InteractiveBiology

    @diimtarsh1 It depends on the ion channel it opens. If it opens a Na+ channels, that causes an excitatory signal. If it opens a Cl- channel, that causes an inhibitory signal. GABA is usually an inhibitory Neurotransmitter. Dopamine can be either excitatory or inhibitory. However, they have different receptors that can open different channels that allow different ions to flow in. This can result in an excitatory or inhibitory signal. Hope that helps.

  13. InteractiveBiology

    It depends on the ion channel it opens. If it opens a Na+ channels, that causes an excitatory signal. If it opens a Cl- channel, that causes an inhibitory signal. GABA is usually an inhibitory Neurotransmitter. Dopamine can be either excitatory or inhibitory. However, they have different receptors that can open different channels that allow different ions to flow in. This can result in an excitatory or inhibitory signal. Hope that helps.

  14. InteractiveBiology

    It depends on the ion channel it opens. If it opens a Na+ channels, that causes an excitatory signal. If it opens a Cl- channel, that causes an inhibitory signal. GABA is usually an inhibitory Neurotransmitter. Dopamine can be either excitatory or inhibitory. However, they have different receptors that can open different channels that allow different ions to flow in. This can result in an excitatory or inhibitory signal. Hope that helps.

  15. varsha

    very nice video!! But could please distinguish between an electrical synapse and a chemical synapse and the way the impulse travels along them??

    1. Post
      Author
      Leslie

      Sure Varsha,

      Electrical Synapse: Gap junctions connect the cells so that they are essentially “electrically connected”. When there is a signal in one cell, the ions flow to the next cell causing a signal in that cell.

      Chemical synapse: This is the one described in the video, and relies on Neurotransmitters that are released into the synapse. The neurotransmitter binds to receptors and a signal is generated in the next neuron.

      Hope that helps!

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  16. hadooish

    great video helped me alot but i have another problem that is related to the classification of neurotransmitters and the drugs effecting them like Ach effected by botulium toxin or GABA by allyglycine etc that is very complicated can you tell me an easy way to understand it…plz

  17. hadooish

    great video helped me alot but i have another problem that is related to the classification of neurotransmitters and the drugs effecting them like Ach effected by botulium toxin or GABA by allyglycine etc that is very complicated can you tell me an easy way to understand it…plz

  18. InteractiveBiology

    @hadooish Glad the video helped. Unfortunately, I don’t have a good summary of that at the moment. Will probably get to doing something like that the next time I cover the Nervous System, but that won’t be for a while. Hope you are able to find good resources. Do a google search and see what you come up with (if you haven’t already).

  19. InteractiveBiology

    Glad the video helped. Unfortunately, I don’t have a good summary of that at the moment. Will probably get to doing something like that the next time I cover the Nervous System, but that won’t be for a while. Hope you are able to find good resources. Do a google search and see what you come up with (if you haven’t already).

  20. InteractiveBiology

    Glad the video helped. Unfortunately, I don’t have a good summary of that at the moment. Will probably get to doing something like that the next time I cover the Nervous System, but that won’t be for a while. Hope you are able to find good resources. Do a google search and see what you come up with (if you haven’t already).

  21. housam

    this video is very grate

    but i have question : what the job of mitochondria the found in presynaptic membrane?

    thank you very much

    1. Post
      Author
      Lrsamuel

      Cells need energy for all of their functions to happen. There are a number of things happening in the presynaptic cell that requires energy. The Na/K pump is one example. It’s found everywhere and requires ATP. Also, in order for the Neurotransmitters to be taken back into the presynaptic cell, that also requires ATP. ATP is made in mitochondria.

  22. juhidgenius

    the action potential is caused by an electrical signal..but now the next neuron recieves a neurotransmitter..which is a chemical..then how does the signal go furthur??

  23. neemasch

    Hello I would like to See some videos about EPSP & IPSP and also about the Summation which classified into temporary and simultaneously

  24. VictorAdrian1492

    This is really helping me understand everything soooooooo much better! Thank you so much! :) I’m gonna keep watching for fun too!

  25. Melissa Fling

    Leslie,
    This video is very helpful, but I have three questions:

    1. What is it about the Ca+ entering the axon terminal that signals the synaptic vesicles to fuse with the presynaptic cleft and release neurotransmitters? How do the Ca+ ions interact with the vesicles to make them do that?

    2. How do the neurotransmitters know to bind to the receptors on the postsynpatic cleft and not just float away in the extracellular fluid? Is there a charge drawing them toward the receptors?

    3. You said that once the neurotransmitters bind to the postsynaptic receptors, that causes a signal inside of the cell. If this cell is not the final destination of the action potential, does the signal initiate another action potential within the cell to send down its axon? Or, in general, I guess I just want to know an example of what kind of signal the neurotransmitters would be sending.

    I know these questions are a bit involved. I’d appreciate your explanations though! Thanks
    Melissa

    1. Post
      Author
      Lrsamuel

      WOW, that’s A LOT to answer in a comment. Not sure I’ll be able to answer them fully, but here are my quick responses:

      1. Calcium interacts with proteins in the membrane of the vesicles and on the presynaptic membrane (SNAP-25, Syntaxin, Synaptotagmin, Synaptophysin – if I’m remembering correctly), causing them to interact in a way that helps the membranes fuse. In terms of the underlying exact mechanism, I don’t know more than that.

      2. The space is VERY SMALL. There isn’t an attraction, but the transmitters fit into the receptors in a way that causes the changes necessary. Some of the transmitter may leak out, but the transmitters don’t stay around long. They are broken down by enzymes.

      3. Yes, it can cause another action potential in the postsynaptic cell, which is then the presynaptic cell for the next postsynaptic cell.

      Hope that helps!

    1. Jeanna Dalton

      We are studying the nervous system right now in physiology, and I agree with you that they are proving very useful! My professor is a med. doctor and sometimes she speaks as if we are a group of professors too! I love these videos because they are helping me to understand what she is trying to help us learn!!!!

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  26. Mohamedddiop

    Ok so I am a premedical student in college and these videos are soo useful for physiology class! thanks for your work.

  27. ehmfrancisco

    Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may also follow graded electrical potentials.

  28. Kelvin

    May I ask what will happen to the neurotransmitters after they have stimulated the channels on the dendrite of the next neuron? Will they go back to the vesicles? If no, how can they deal with the coming next signals????

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  29. Jennis Singla

    action potential is an all or none concept. for more neurotransmitter to be released you need more action potentials. hope that helps! :)

  30. pyro5445

    This is a very good video. You explained the process very well. Our Anatomy book made the release of neurotransmitters very unclear because it did not distinguish between the postsynaptic/presynaptic membranes. Thanks for the informative video!

  31. naturaloriginal

    I love your pronunciations and your style of explaining things. For someone who speaks English as a second language , is important to understand clearly (as you wonderful do ) terms and names. I am looking for a lesson with how neurotransmitters are retrieved.

  32. Anne W

    Thank you so much for your videos. They are very helpful! I have a question with regard to the action potential. Is it correct that the action potential is caused by the neurotransmitters bringing EPSP and IPSP where the summation is sufficient to depolarize the membrane to its threshold of exicitation? Is the Action potential also generated by the neurotransmitters binding to ionotropic receptors which cause sodium to rush in? And at last, can you tell me what is the case for Serotonin? Thanks!

  33. Brandon Scherrer

    Thank so much, it’s so much easier to understand with a narration and diagram, thank you!

    I was just wondering how are the Neurotransmitter made? Serotonin is produced for example by exercise, how is it that the serotonin neurotransmitter is produce in neurons?

  34. christy benhaim

    Thank You soooo much, I got an “A” on my last A&P exam!;~) You explain things very well. Do you have any …more(?)… interactive lessons? For example clicking on a word in the image to see it defined or labeling exercises?

  35. Polina Korneeva

    Thanks a lot, I’m currently doing my psychology A level and your video was a lot of help. I also wanted to ask how do the synaptic vesicles fuse with the presynaptic membrane. I haven’t watched your previous videos so I don’t quite understand what exactly the synaptic vesicles are and what is the pre-synaptic membrane made of etc.

  36. Ghosty Coman

    Thank you so much, this makes everything so much easier to understand! I think I’m going to take notes on this at least as much as I did on my chapter.

  37. Annalie hall

    this video was very helpful thank you. you should also add what happens when the neurotransmitter binds to the receptors, and the EPSP’s and IPSP’s.

  38. Caitlin

    I need to make a drawing that explains the difference between how this normally works and how it works with alcohol. I don’t quiet understand what happens with the nervous system with alcohol though. Can you help me?

  39. Michelle Jacobs

    This is really great. Wondering if you are going to do sections on each of the different neurotransmitters and their functions. That would be helpful.

  40. Alain Lievin

    Very helpful video.

    Are neurotransmitters released intermittently according to the activity of the presynaptic terminal or they are released continuously if the presynaptic neuron is receiving input onto its dendrites.

  41. ranjana

    hey i pretty much understood the concept of transmission of neurotransmitter..can you please explain excitatory post synaptic potential and inhibitory with an example.love your site.god bless and thanks!.:)

  42. juan rosa

    Leslie,
    I enjoyed theis video on neurotransmitters, you made it easier to understand how a neurotransmitter is released. I was wondering if you would delve into the three most important neurotransmitters, and their types and subclasses. thank you for the tutorials, you are making biology a bit easier and definitely more fun.

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