017 Two Types of Receptors

017 Two Types of Receptors

Leslie Samuel IBTV, The Nervous System 161 Comments

After neurotransmitters are released from the cell, they bind to receptors on the next cell.

In this video, Leslie explains how the two different types of receptors – the ionotropic and metabotropic receptors – work to bring about various responses in the cell.

Enjoy!

Transcript of Today’s Episode

Hello and welcome to Interactive Biology TV, where we’re making biology fun! My name is Leslie Samuel. In this episode, Episode 17, I’m going to be talking about 2 types of receptors. We’ve been talking about the nervous system, we’ve been looking at neurons, and we’ve seen how the action potential starts at the axon hillock, the signal travels all the way down the axon, down to the axon terminals. In Episode 16, we looked at how the neurotransmitters are released from the axon terminals, and they bind to receptors on the next cell.

What we’re going to be doing is looking at those receptors because there are 2 basic types of receptors:
1. Ionotropic
2. Metabotropic

What we’re going to do is we’re going to look at the ionotropic receptors first. With ionotropic, these are very fast-acting receptors. What I’m going to do is I’m going to attempt to draw one now. Let’s say here we have a receptor, and this is a cell membrane. We have the signal that comes along the axon of the preceding cell, and it releases neurotransmitters. I’m going to say these little dots here are neurotransmitters, and they’re in the synaptic cleft.

What’s going to happen if it’s an ionotropic receptor, the neurotransmitter is going to come and it’s going to bind to the receptor. The way these receptors are set up is relatively simple. When the neurotransmitter binds to the receptor, that causes the channel to open. So, I’m going to draw this showing that now there’s an open space. And then, if there are ions that are outside the cell that are specific to that channel, those ions can then enter the cell. So it’s very fast-acting. The neurotransmitter binds to the receptor, and then the channel opens so that the ions can travel inside the cell. Once again, these are ionotropic receptors.

Now, of course, there are going to be different types of neurotransmitters and different types of receptors that are going to act in this way. I’m going to take the example of acetylcholine as a neurotransmitter. So we’re going to start with ACh, and that’s for acetylcholine. We’re going to call these neurotransmitters acetylcholine, and the receptor that’s the ionotropic receptor for acetylcholine is called the nicotinic receptor. The reason it’s called nicotinic is because this is the receptor that nicotine acts on, and we’re going to talk about that in a later episode.

So, acetylcholine comes, and actually 2 acetylcholines bind to the nicotinic receptor, and then that causes sodium ions to rush in. And now you know that sodium ions are going to have a positive charge, so what do you think that’s going to do to the membrane of the cell? Well, of course, that’s going to make it more positive. So I’m going to look at it here. Let’s say I’m looking at voltage or membrane potential on the Y-axis, and I’m going to have time on the X-axis. This is the resting membrane potential.

When something like this happens that causes sodium to come in, that can cause the membrane potential to get this little bump here. So it increases a little from that sodium rushing into the cell. Because this is becoming more positive, we’re going to call this an excitatory (it’s getting it excited) post-synaptic potential. EPSP, excitatory post-synaptic potential. Because it’s acetylcholine binding to the nicotinic receptor, that’s going to cause sodium ions to rush in, causing an excitatory post-synaptic potential.

Now, there’s another type of neurotransmitter, 2 examples would be GABA and glycine (forgive my writing there, but I think you get it.) When these bind, let’s say this is GABA or glycine, what that is going to do is it’s not going to cause not sodium ions, but chloride ions, and let’s say this is chloride, Cl-, to rush into the cell.

If a negative ion rushes into the cell, what is that going to do? Well, you probably guessed it. Instead of causing an excitatory post-synaptic potential, that’s going to cause an inhibitory post-synaptic potential, or an IPSP. So if it’s a positive ion rushing in, you get an EPSP. If it’s a negative ion rushing in, you’re going to get an IPSP. This is a really fast-acting process: neurotransmitter binds, channel opens, ion rushes in.

Let’s go to the next type of receptor, and that’s called the metabotropic receptor. This is going to be a little more complicated, because what we have here, just like before, we have a receptor in the membrane. And just like before, we have neurotransmitters that are outside the cell. But what’s different here, is that inside the cell, associated with this receptor, we have a G protein.

What happens is this neurotransmitter comes and it binds to the cell, just like before, and instead of opening a channel, what that does is it activates the G protein. And then this G protein then goes on to activate a second messenger system where there can be multiple processes that are happening, causing a certain response on the inside of the cell.

So this is a slower process in that there are multiple processes happening, and it causes a different type of response. That response can be a number of different things, and we’re going to talk about that a little later.

An example of a metabotropic receptor would be the muscarinic receptor. With the muscarinic receptor, acetylcholine is still the neurotransmitter, so ACh, and that binds to the receptor that activates a G protein. When it activates a G protein, a number of processes happen that cause multiple responses, depending on the type of muscarinic receptor we’re dealing with. One of the features that we have here is for every neurotransmitter that binds, that can activate a G protein, and whatever process this is can happen multiple times, and then this process this is can happen multiple times, so that we get a greater response on the inside.

For example, I’m just going to take a random number. Let’s say here we activate 1 G protein, and this process can happen 10 times, and each one of those can cause this next process to happen 10 times. So this second messenger system can result in a significant amount of amplification, so that we can get a significantly greater response.

Those are the 2 types of receptors: we have the nicotinic receptor and we have the muscarinic receptor. If you have any questions about this, you can leave them in the comment section below, or you can just leave a comment letting me know what you think about the format of what I’m doing, and even give suggestions for future episodes. That’s it for this video, and I’ll see you on the next one.

Comments 161

  1. daniel

    what is the difference between intracellular and plasma membrane receptor? what is their function please.

    thank you. your videos are very helpful.

  2. kavvyr

    dude u r soooooo awesome. u go thru everything i am going thru in my class
    currently! i “like” or “thumbs ups” all ur vids i watch :D

  3. varsha

    i had a doubt.let it be an EPSP or an IPSP, when they cause the membrane potential to be positive or negative respectively,then how does the membrane potential to get to normal again as in the graph you have drawn in the video??? could you please give an explanation for this?

  4. Mariam

    I came across your videos today and I have learned more in the last 17 episodes than I have in two of my Neuroscience classes! Thank you so much for your awesome explanations!

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  5. marilyn pechbrenner

    I have been blessed coming across your video’s. They have helped me tremendously!! i wish you could make more. i would love one on the cranial nerves (if you know an easy way of learning the 12 pairs) with your physiology it would be nice if you could add a pain receptors and the importance of pain in the nervous system

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      Leslie

      Thanks Marilyn.

      I appreciate your feedback and I’m so glad that they are helping you so much. I do plan on making more, but all in due time. It will take some time, but the goal is to make the biggest library of good quality Biology Videos online. Quite a daunting task, but I think I’m up to it :)

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  6. Natalie

    You’re awesome man!!! Keep up the great work, we need you!! :D I’m learning tons because of this and it truly is fun to learn!!! Thank you Leslie Samuel!! :)

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      Lrsamuel

      Thank you so much Natalie. Comments like these make me want to hit it hard and come out with a million new videos, lol. I’m glad they are helping you so much. You are VERY MUCH welcome!

  7. Dave Moyer

    Sir,
    Thanks for the clarity and simplicity of your presentations. Can you apply the same kind of analysis to the following?
    1. How do GABA interneurons cause inhibition of nearby neurotransmitters?
    2. How do hypofunctioning NMDA recepors (blocked by kynurenic acid or diminished by oxidative stress)cause a dopamine storm?
    3. What causes GABA interneuron hyperpolarization. What is the effect of it?
    4. What role do GABA interneurons play in the filtering and prioritization of impulses sent to the prefrontal cortex.

    I come from a non technical background and have been struggling with these issues for some time. Thanks for any assistance you can provide.

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      Lrsamuel

      Those are all great questions. However, I’ve finished dealing with the nervous system for now, because I need to get on to covering other topics. Unfortunately, I won’t be able to do that at this moment. I hope that you can find as much value in the other videos and the ones that I will start working on next week.

      All the best!

  8. Katy Braddick

    I’m doing a degree in Biomedical Science and I have found your videos so
    helpful! They are so much easier to understand than anything I have been
    able to find on the internet or in text books! Thanks so much and I hope
    the videos carry on!! :-)

  9. Lori

    Oh my goodness….I have listened to our instructor for 2 days discuss this and I couldn’t get it. I watched your video one time and it totally makes sense. Thank you so much!

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  10. DoonGirl18

    Thank you so much!! I’m studying Neuroscience but I’ve never done biology before so I was finding it really hard but your videos are amazing help…especially for a visual learner like myself!! Thanks to your video i finally understand what my crazy physiology lecturer was talking about! Thanks :)

  11. InteractiveBiology

    @DoonGirl18 You are very much welcome. Glad to know the videos are helping
    you to understand your crazy lecturer, lol. I plan on doing many more, so
    stay tuned. All the best!

  12. Djalitana

    ok I went back to my book and watch this clip again. now I know it doesn’t need to be necessarily sodium Ions , it can be any other ion to get into the cell and depolarise or hyperpolarize the post synaptic neurone or muscle. thank you so much.

  13. UnagiTap

    @Djalitana Ca2+ is for the release of neurotransmitters from the vesicles in the PRE-synpase. The action potential opens Ca2+ channels. Calcium binds to vesicles and release. So then it now depends on which neurotransmitter and what type of POST-synaptic receptor it is like described above.

  14. UnagiTap

    @Djalitana Ca2+ is for the release of neurotransmitters from the vesicles in the PRE-synpase. The action potential opens Ca2+ channels. Calcium binds to vesicles and release. So then it now depends on which neurotransmitter and what type of POST-synaptic receptor it is like described above.

  15. UnagiTap

    Ca2+ is for the release of neurotransmitters from the vesicles in the PRE-synpase. The action potential opens Ca2+ channels. Calcium binds to vesicles and release. So then it now depends on which neurotransmitter and what type of POST-synaptic receptor it is like described above.

  16. UnagiTap

    Ca2+ is for the release of neurotransmitters from the vesicles in the PRE-synpase. The action potential opens Ca2+ channels. Calcium binds to vesicles and release. So then it now depends on which neurotransmitter and what type of POST-synaptic receptor it is like described above.

  17. msss432

    Quick question first you say that AcH’s receptor is Nicotinic recetor then… you had the AcH’s receptor as the Muscarinic…… Can any neurotransmitter have any receptor? Or does each have its own receptor?…. Overall your great by the way

  18. msss432

    Quick question first you say that AcH’s receptor is Nicotinic recetor then… you had the AcH’s receptor as the Muscarinic…… Can any neurotransmitter have any receptor? Or does each have its own receptor?…. Overall your great by the way

  19. InteractiveBiology

    @msss432 Oh, I’m sorry. Leslie will not be able to entertain any more questions as he is busy with a lot of stuff right now, and creating more videos for the site. He’ll be tackling more topics so, stay tuned for more!

  20. InteractiveBiology

    Oh, I’m sorry. Leslie will not be able to entertain any more questions as he is busy with a lot of stuff right now, and creating more videos for the site. He’ll be tackling more topics so, stay tuned for more!

  21. InteractiveBiology

    Oh, I’m sorry. Leslie will not be able to entertain any more questions as he is busy with a lot of stuff right now, and creating more videos for the site. He’ll be tackling more topics so, stay tuned for more!

  22. NeedsAHardOne

    @msss432
    I dont think any neurotransimitter can bind to any recepter, but there is a variety that one can bind to.
    ACh does bind to both nicotinic (which I think has excitatory effects) and muscarinic (which can be either excitatory or inhibitory and only occurs in the parasympathetic system).
    Depending on where the synapse leads to (muscle fiber, neuron, gland, etc) determines which receptors are available for the neurotransmitter.

  23. NeedsAHardOne

    I dont think any neurotransimitter can bind to any recepter, but there is a variety that one can bind to.
    ACh does bind to both nicotinic (which I think has excitatory effects) and muscarinic (which can be either excitatory or inhibitory and only occurs in the parasympathetic system).
    Depending on where the synapse leads to (muscle fiber, neuron, gland, etc) determines which receptors are available for the neurotransmitter.

  24. NeedsAHardOne

    I dont think any neurotransimitter can bind to any recepter, but there is a variety that one can bind to.
    ACh does bind to both nicotinic (which I think has excitatory effects) and muscarinic (which can be either excitatory or inhibitory and only occurs in the parasympathetic system).
    Depending on where the synapse leads to (muscle fiber, neuron, gland, etc) determines which receptors are available for the neurotransmitter.

  25. Chipotle3333

    You are a God send. Thank you so much for your work, this puts everything into perspective in a clear and concise manner.. Right in time for my final too :D Which is in an hour…..

  26. 4misspennylane

    Honestly, InteractiveBiology is heaven sent. You are like my own personal tutor!
    My professor always makes all of this sound so foriegn, meanwhile you manage to get me to understand a topic in less then 10 min. THANK YOU SO SO SOOO MUCH! <3 Sending you much love from NY! = )

  27. 4misspennylane

    Honestly, InteractiveBiology is heaven sent. You are like my own personal tutor!
    My professor always makes all of this sound so foriegn, meanwhile you manage to get me to understand a topic in less then 10 min. THANK YOU SO SO SOOO MUCH! <3 Sending you much love from NY! = )

  28. Haldouda

    You are awesome! I enjoyed the clip, you are clear, to the point, fast and short:) Thank you much. Wish me luck for my test tomorrow:)

  29. pavan

    Hi Leslie a great website which is helping me get back to the basics, I have a doubt if you plot a graph for G protein linked signal transduction will you get only one peak or multiple peaks ?

  30. Saks

    Samuel, May God bless you for your efforts. This is unconditional dedication and you are a great teacher. I wish you the best in life!

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  31. Bodyskillz2011

    hi sir thanks for the Vid they are very helpful, i have a question u was talking about Muscariniq receptor so its a metabotropic receptor or not ? and the neurotransmitter bind with the muscariniq receptor and then activate the G proteine ? or just bind with the G prot? x)

  32. Bodyskillz2011

    hi sir thanks for the Vid they are very helpful, i have a question u was talking about Muscariniq receptor so its a metabotropic receptor or not ? and the neurotransmitter bind with the muscariniq receptor and then activate the G proteine ? or just bind with the G prot? x)

  33. Lauren P

    Wow thank you for this!! I’ve spent a week trying to understand this concept, and you managed to clarify it in under 10 minutes! Thanks a million :)

  34. sweetpea1Peter3

    Thank you!!!! I spent hours of researching online, trying to understand/teach myself this process. You explained it so clearly and simple, I understood it right away.

  35. Anthony Selkowitz

    Unless you were asking about whether each receptor only allows a specific type of neurotransmitter to activate it. For example, most inhibitory ionotropic receptors use GABA. Many Metabotropic receptors accept different types of neurotransmitters. The important part is where the metabotropic receptor is located, not necessarily the types of neurotransmitter it accepts.

  36. Lamees Awwad

    I’m a 1st year med student and you couldn’t have explained the process more beautifully .. This has been helpful !! Thank you so much!!!

  37. chen582

    it was so helpfull!!
    my language is not English but steel it was so easy to me to understand it!
    so, thank you so much for this!!

  38. Bosele Pebe

    You should have explained what happens once G-protein is activated, through to synthesis of cAMP till kinase action.. Thats where its a bit tricky..

  39. Younness Dehbi

    Well Sir, I’m a nursing student, and I it took 8 hours to explain what you just explained in 9 min, THANK YOU VERY MUCH

  40. Bickity Banks

    Thank you very much for posting this series of videos! I am LEARNING a lot from them. You explain everything clearly and concisely. Seriously, my grades are improving because of your videos.

  41. Ndunaija

    You are my physiology HERO. I feel more confident about the course now that I have you around. You are an amazing instructor.

  42. chocolateddy22

    wow….that makes soooo much more sense now!! thank you!!! (if I pass my exam it’ll be thanks to you!!)

  43. Jae Young Kim

    Oh my God Thank you so much Leslie you really wouldn’t understand how much help I got from this 10 min clip… THANK YOU!!

  44. Gabrielle Fillion-Bertrand

    Thank you very much for your good explanations. I speak French and your language is easy to understand. It is clear and concise. Keep it up.

  45. Yogesh Subedi

    Hey guys. Outstanding movie. My good friend used to be a flabby. He went from 285 lbs of pure fat into 215lbs of massive muscle mass. That shit was crazy! I just subscribed personally as I plan to boost my entire body. He used the Muscle Building Bible (Look in Google)…

  46. hadasdel

    what happens after that?
    how does the reuptake works?
    I have an exam on friday and so far your videos are the only thing that helps me :)

  47. Josef Shivute

    wow this is really awesome…..i watch ur videos to understand topics i dnt understand in my physiology class..thank u very much

  48. hunger4jsutice

    Once again, a wonderful, clear, concise explanation that changes learning from wrote memorization to understanding and long term retention. You are one of the reasons I am getting As in Anatomy and Physiology. THANK YOU!!!!

  49. Hannah Murphy

    Thank you so much :-) In my exam yesterday i had an essay on the three stages of chemical signaling and your videos helped so much :-)

  50. Kloszewska

    I am in an advanced brain anatomy class in my Psychology major… I do understand a lot but your videos are GREAT for the visual understanding part of it.
    Thank you so much! :D

  51. Linda Holder

    I wanted to find out if you block a muscarinic receptor what will happen? I am studying neuroleptic medications and trying to understand the way these work. I am not sure you can help, but anything would be appreciated. Thanks

  52. Carolyn Foster

    Great videos :D find I’m learning things so much easier and understanding so much better when I can listen to you explain and watch you illustrate each step of a process; a million times better than just reading through pages and pages of text!

  53. Kellie Tunney

    Thank you so much! Watched a 50 minute lecture… made no sense. Watched this along with your synapse video and it’s so clear! Keep the physiology videos coming!

  54. smilebeautifulworld

    Thank you that’s such a good explanation :) but i have one question .. we have learned that a.p have a property of one way propagation.. so the post synaptic cant receive an a.p if it’s already excited.. right? also the ipsp is also to stabilize the membrane rather then to hypopolarize.. So the question is.. how does the the ipsp stabilizes already excited membrane? I mean the only way for the neuron to recieve a second potential is to be in refractory period .. Hope you understood my confusion.

  55. lina mateeva

    ok I’m studding bio psychology and for the first time it actually made sense!!! I only wish i found these tutorials sooner bf my test:))))thank you, thank you, thank you!

  56. Dikshhya Acharya

    Crazy clip. Superb clip. My pal had been fat. He went from 293 lbs of fat into 212 lbs of absolute muscle mass. I could not believe it! I just signed up myself coz I’m looking to get big muscles. He made use of the Muscle Building Bible (Look in Google)…

  57. kamikazeicecream

    This is because the IPSP or EPSP we are talking about is on ANOTHER neuron across the synaptic cleft (space). You are right about the refractory period though, just that we are talking about two neurons here, not just one.

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