020 Facilitation

In this video, Leslie explains all about facilitation and illustrates how it causes a stronger and longer signal in the post-synaptic cell.

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. In this episode, I’m talking about the process of facilitation, and we’re going to look at how this leads to a longer and stronger response in the post-synaptic cell.

Here, I’m looking at a neuron, and let’s say there’s an action potential that comes along this axon and enters into the axon terminal. I’ve drawn this terminal a little bigger than the previous ones because there’s a lot of stuff that I wanted you to see in here. As we’ve mentioned before, when the action potential reaches the axon terminal, it causes voltage-gated calcium channels to open, calcium ions rush in and that causes the vesicles to fuse with the membrane, releasing neurotransmitters, causing a signal in the post-synaptic cell. Now, this calcium that rushes in also causes depolarization because this has a positive charge. Usually, what happens after that is voltage-gated potassium channels open and potassium rushes out of the cell, repolarizing the membrane, ending the signal, ending calcium coming in, ending the neurotransmitter release.

In the process of facilitation, we have this facilitatory neuron, or you can call this a pre-synaptic synapse, and this neuron releases the neurotransmitter serotonin. When it releases that neurotransmitter serotonin, that binds to the receptor, and this is a metabotropic receptor, and this one specifically activates a G protein. That G protein activates adenylate cyclase. Adenylate cyclase converts ATP to cyclic AMP, which then activates a protein kinase, specifically protein kinase C, so I’ll put a C right here. That protein kinase phosphorylates the voltage-gated potassium channels, and what that does is it shuts those channels so potassium cannot leave as easily as it would have in a regular situation.

So the net result here is, we have an action potential that comes down, we have depolarization, but instead of repolarization happening quickly, repolarization takes longer to happen. It causes the action potential, the signal here, to last longer. And, of course, what that’s going to do is it’s going to cause more vesicles to fuse with the membrane, and you’re going to end up with more neurotransmitters being released. That, of course, is going to result in a greater signal in the post-synaptic cell.

So once again, action potential comes along, voltage-gated calcium channels open, calcium ions rush in. But we have this secondary neuron, a secondary synapse that releases serotonin, binds to the receptor, activates a G protein, which activates adenylate cyclase, converts ATP to cyclic AMP. That activates a protein kinase C, which phosphorylates the voltage-gated potassium channels, causing them to close, allowing the signal to last longer and for more neurotransmitters to be released, resulting in a stronger signal, a longer signal in the post-synaptic cell.

That’s really it for this video. If you have any questions, go ahead and leave them in the comments, and I’ll be happy to answer them. That’s it for this video, and I’ll see you in the next one.



You may also like

Page [tcb_pagination_current_page] of [tcb_pagination_total_pages]

  • I am very pleased by your clarity and teaching style. While in medical school, I could never completely understand the physiology of facilitation, summation, etc. With such topics,it really makes a difference in how well the subject matter is explained. Thank you for making this topic totally understandable. I will reviewing more of your lectures while I study for my board exams.

  • Wow, that’s awesome to hear. I’m excited to know that you are finding such value in the content, even at the level of studying for your medical board exams. Thanks for leaving the comment. I really appreciate it. I’m also going to be posting many more videos on a regular basis to build up a repository of videos covering a wide variety of biological topics. Feel free to share the site with your classmates and help me get the word out there 😀

  • your videos are really interesting!!but i had a doubt.when does facilitation actually happen??i mean why is the repolarisation delayed ,so as to promote what??why doesnt it always happen??the signal always needs to be stronger. doesnt it?i hope you get my question!

  • When the neurotransmitters attach to receptors on another neuron, where do they attach in the neuron? the soma, dendrite or do transmitters attach to another axon terminal?

  • When the neurotransmitters attach to receptors on another neuron, where do they attach in the neuron? the soma, dendrite or do transmitters attach to another axon terminal?

  • @msss432 Leslie no longer has the time to entertain specific questions nor entertain requests for new videos. He’s been busy with a lot of stuff lately. But, he will definitely get to more systems and other Biology topics in the future. So, please stay tuned for more!

  • Leslie no longer has the time to entertain specific questions nor entertain requests for new videos. He’s been busy with a lot of stuff lately. But, he will definitely get to more systems and other Biology topics in the future. So, please stay tuned for more!

  • Leslie no longer has the time to entertain specific questions nor entertain requests for new videos. He’s been busy with a lot of stuff lately. But, he will definitely get to more systems and other Biology topics in the future. So, please stay tuned for more!

  • Sir, in this episode the figure drawn is little bit clumbsy. Please drawn a big figure to clarify Facilitation. . .

  • @msss432 I know this comment is probably a little late, but according to Cognitive Neuroscience by Banich and Compton the neurotransmitters move from an axon to a dendrite usually. They are released from the terminal buttons on an axon and then absorbed by the dendrite of another neuron. I think its called reuptake.

  • I know this comment is probably a little late, but according to Cognitive Neuroscience by Banich and Compton the neurotransmitters move from an axon to a dendrite usually. They are released from the terminal buttons on an axon and then absorbed by the dendrite of another neuron. I think its called reuptake.

  • I know this comment is probably a little late, but according to Cognitive Neuroscience by Banich and Compton the neurotransmitters move from an axon to a dendrite usually. They are released from the terminal buttons on an axon and then absorbed by the dendrite of another neuron. I think its called reuptake.

  • The reason of facilitation happening is because the stimulation isn’t enough to generate an action potential and with it we can reach the action potencial?
    We have a neuron doing sinapsis with another but we can’t generate the action potential so we do facilitation to increase the number of neurotrasmitters in order to rise stimulation.
    But there’s a relation between the potential of membrane and the secretion of neurotrasmitters (i mean,secretion it’s only possible with despolarization)?Tnks!

  • I am studying for my Anatomy and Physiology final and this video was soooo helpful! I wasn’t understanding Facilitation until I watched this. Thank you so much. 🙂

  • {"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}

    Get in touch

    Name*
    Email*
    Message
    0 of 350
    >