The Cholinergic Receptors
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- เผยแพร่เมื่อ 2 ต.ค. 2024
- Understand the cholinergic receptors once and for all!
The Cholinergic Receptors.
This is a high-yield topic.
You really need to understand this when you're going into your boards or exams.
These receptors are found in the central and peripheral nervous systems, and they use Acetylcholine as their neurotransmitter.
Thus, they can also be referred to as Acetylcholine Receptors, and their abbreviation is ACh for Acetylcholine and R for Receptor.
There are two main types of these Cholinergic Receptors: the Nicotinic Acetylcholine Receptors and the Muscarinic Acetylcholine Receptors.
The Nicotinic Acetylcholine Receptors are named such because they are responsive to both Acetylcholine and Nicotine.
They are ionotropic receptors, meaning that they are ligand-gated ion channels.
When stimulated by their neurotransmitter, they themselves become an ion channel.
The Muscarinic Acetylcholine Receptors, on the other hand, are named such because they are responsive to Acetylcholine and Muscarine.
They are a different kind of receptor.
They're what's called a Metabotropic Receptor, meaning that they act through a second messenger system, which in this case refers to the fact that they are G protein-coupled receptors.
Let's talk about the Nicotinic Cholinergic Receptors first, and this is abbreviated the same as what we've seen, AChR, except now with an "n" in front of it to denote Nicotine.
So the Nicotinic Cholinergic Receptors, they're directly linked to ion gated channels, as I previously said.
There is no second messenger system here.
The receptor is a physical part of the ion channel.
These ion channels are made of five subunits, and they're arranged symmetrically around a central pore through which ions travel when opened.
Also, each of these five subunits is made of four domains, which we might talk about later.
However, it's not necessarily high-yield right now.
When stimulated by either Acetylcholine or, remember, these are Nicotinic Cholinergic Receptors, so either Acetylcholine or Nicotine can stimulate them, there is an initial stimulation, an initial opening, followed by a blockage or a refractory period.
This is important and interesting to talk about because it's related to how some of the drugs work that we will talk about in other lectures.
Let me give you a quick visual example of what is happening when these receptors are stimulated.
I am going to place two molecules of Acetylcholine on the screen and then two separate ions, and these ions can be Sodium, Potassium, Calcium, and so forth.
So what is going to happen is that the Acetylcholine molecules are going to come down and interact with the receptor/ion channel.
This is going to cause a conformational change in the shape of the ion channel, which is going to open the central pore to allow ions through.
Let's take a look.
Kind of interesting, isn't it? Let me repeat this a couple of more times.
Kind of neat how that works, huh? Well, as if we didn't have enough abbreviations to remember, I have to add two more, unfortunately.
There are two sub-types of the Nicotinic Acetylcholine Receptors: the Neuronal-type, abbreviated Nn, and the Muscle-type, abbreviated Nm.
The Neuronal-type is found in both the central and peripheral nervous system, and it is most often found "Up-Stream" in the nervous system, from other receptor types.
So take for example the sympathetic nervous system and the associated Adrenergic Receptors.
For a sig to get through to the Adrenergic Receptors, it must first travel through a Neuronal-type Nicotinic Receptor in an "Up-Stream" ganglion or nerve.
The Muscle-type Nicotinic Receptors are found post synaptically in the Neuromuscular Junctions, and they are responsible for our skeletal muscle contraction.
They are what let us move and breathe consciously.
So keep these two subtypes in mind.
At the end of this lecture, I will give a picture and an example and walk you through where they are.
But for now, let's skip on to the Muscarinic Receptors.
Okay, so the Muscarinic Receptors are a little bit different than the Nicotinic Receptors.
First of all, they're named Muscarinic Receptors because they are responsive to Acetylcholine and Muscarine.
Also, they use a second messenger system to propagate the signal.
In this case, it's the G protein-coupled receptors.
I am not going to go into great detail on the G protein-coupled receptors.
There will be a separate lecture for that.
However, just as an overview, let me walk through what's happening.
This picture on the right represents six basic steps of a G protein-coupled receptor.
Let's zoom in on step one.
Okay, what we have here is the receptor within the membrane of the cell.
The brown oval near the top represents the ligand.
In this case, we're talking about Acetylcholine or Muscarine.
The ligand binds to the receptor and induces a conformational change.
This conformational change activates the alpha sub unit, which then exchanges its GDP for GTP.
Every time he says "ISN'T THAT COOL" I find myself grinning while nodding enthusiastically like what the hell!
This is SO cool! I can't believe how much I used to hate that shit when they actually make a lot of sense!
Just THANK YOU! You're my hero ❤
I know right. ...so damn cool
One of the best channels for medicine.
This is the most informative and interesting pharmacology lecture I have ever heard! Thanks alot!
u sir are FRIKKING BRILLIANT!!! dude that was 1000% times better than my boring as hell lecturer DUDE, all my love
you are like... THE HERO !
F
Indeed
Great videos ! I have a much clearer understanding of the receptor functions now thank you. Could you possibly make videos regarding Gi and Gq proteins please?
Yeah, this lecture was the shit. I am studying pharma right now for my NCLEX exam I am taking soon, and I am too lazy to just memorize without understanding therapeutic/side effects of medications without at least trying to understand WHY they exist. Videos like this really hammer home concepts that allow me to understand and not just memorize side effects, etc. I feel like much of the nursing text spits out terms that we just don't have enough time to delve into further. I have a problem with that. (I have OCD) I loved the diagrams for the PNS and SNS systems and the nerve innervations. Explanations were super clear. Even as a nursing student, I did pick up on the 'Chromotropic' error, haha. I am just not content to know the basics, I need more because it scares the shit out of me in a good way that my knowledge of this stuff is gonna help me to better communicate to providers to increase patient safety. Thanks.
+Scott Genereau - Good luck dude!
hahaha lolz i thought you wrote "Yeah, this lecture was shit" i was like da hell this is good hahah
Scott Genereau
Ur comment is too long
Goodman & Gilman's the pharmacological basis of therapeutics has an excellent description of the autonomic nervous system and how drugs function on it. You won't have to memorize. This cannot be memorized. You have to understand the logic.
so nice …. so cool ...good luck
just superb !
thanks doc,you have helped me on this,thanks allot.
This is really helpful. I was quite confused when I first learned this in class, now I'm studying for step 1 and the language had be SUPER confused. For instance, people using the words anticholinergic and antimuscarinic interchangeably with parasympathetic inhibition - when in fact they aren't the same. This video really helped me to understand what the differences are between those - it all has to do with the different sub-types of receptors.
I'm glad I could help Lomo!
Thank you so much for this! Thank you!! You've really helped me, I have been struggling with these concepts for s long and now that I finally get it I feel a lot more confident about my finals, thank you so much
This is the first video on these receptors that actually helped me. Thank you so much!
Kankate Aishwarya Vitthalrao
Roll no- 26
chronotropy, not chromotropy. great lecture.
Yeah, I need to fix that! Thanks!
quand le sage montre la lune , l'imbécile regarde le doigt.
You are 100 % true bro
Stupid shit
THis was a great lecture
which is why i too said, "great lecture". but what the heck is wrong with helping correct a tiny error but one that could be confusing (there's chronotropy, dromotropy, and then chromotropy gets thrown in there now)? this was not a criticism, and not stupid shit. it was minor shit. very minor. but that is a common thread with commenters on the internet- they take things too personally. this guy does a great lecture, and i think i watched severall other flawless lectures. now he can make this one flawless. wtf is wrong with that? maybe you took offense because you have thin skin or something?? she or he took it appropriately as it was intended- to be HELPFUL.
loved it !!!
Thanks Joe.... U realy awsm... Pls upload more and more....
good lecture
OMG!! this is awesome 😍
thank you
This is the best summary video I have found so far for cholinergic receptors. THANK YOU!
Thank very much
i mean...dude YOU ARE AMAZING!!
Your videos on receptors has been HUGE for me! Thanks so much.
Thanks man you helped a lot
you are amazing thank u so much
I almost cried... so... perfect. Thank you very much for making this lecture.
Awww - I almost cried at your nice comment... I'm a resident right now guys so I'm sorry that I don't have time to work on medimmersion. Hang in there, school is over before you know it!!
Not all heroes wear capes
Awesome
So what does smoking do? You get nicotine. So does that attach to your parasympathetic nerves?
Brother can you plz give the link to download that images of shit of sympathetic and parasympathetic, which you explain
love you!
After taking brahmi, shankapushpi for one month my memory is weak and cant able to sleep deeply. Need help.
great :) tnk you
Excellent explanation and elaboration. You made it so interesting. Thanks
Great work mate, this is way more helpful than my lazy Pharmacology lecturers.
Good! I'm glad you like it. Stay tuned for more mate! : )
Why doesn't smoking a cigarette stimulate skeletal muscle contraction?
Thank you this is soo helpful 👌🏻❤️
Thank you so much! I finally understand!
Doc if you can send us the link for your slides that will also help thanks
y u said heart has nicotinic Receptors please explain !!
I see your video first time and it's really cool😅😎😎,
Clarity!
Thanku very much! I have been searching for this kind of video for a quite long time. Annnd I finally found it thanks to you sir! I wish you stay healthy and make this kind of videos in future too.
Pls upload video of cholinergic agonist and antagonist
اريد شرح مثله ع مترجم وين الكا هيج شرح نصا
How nicotinic receptors facilitates the rest and digest?
Is it safe to assume, that since ALL preganglionic neurons are cholinergic, ALL postganglionic neurons have nicotinic receptors on them?
anybody got the link to the diagram he showed??
can you please make a lecture on multiplicity of action of Ach...?? it will be a great favour
**ChroNotropy not chromotropy :D, Chronos= time, chroma= color :P great lecture!
+Derrick A. Dabian - Haha! Yeah I know! I need to update the video. Thanks dude.
awesome man . very detailed and easy explaination .
excellent in every respect! thanks so much
thank u so much for all useful videos .do you have any videos for cholinergic antagonist or agonist?please
This is really helpfull thank you so much sir
What is the link to the diagram? I don't see any description posted. Thanks! Great Video!
You're videos are AWESOME! I'm really learning a lot!
very pedagogic explanation!!!
Deshmukh Yashvant Abaji, Roll No-10
Sir,
you're a life saver and a great instructor
Nailed it! Shoulda watched this the first time I learned all these. I think I won't forget.
OMG! this lecture saved my life!!!!!!
the fantastic vedeao i got today, easy perfect ,i hope more and more or all pharmacology
Best video on this topic and ive watched all of them! Thank u! 🙏🙏🙏
these lectures are just awesome but i need others too e.g., indirect adrenergic agonists or adrenergic antagonists etc
This is the best video ever. Thanks
Thanks a lot. Where can i get a link for the image of receptor's chart? Thanks
Fantastic! Any chance there are printable notes to accompany this lecture?
Awesome video man, you sure clarified so much clutter!
Really helpful! Thank you! :D
Do you have facebook account? I do have some questions that need to ask you more. :)
Hey I'm having trouble finding the link for the print outs. Can you tell me where they would be?
I'll put them in the description as soon as I get a chance. Thanks!
Thank you very much!!! Also, your videos are very helpful. Im a first year pharmacy student and I was completely lost when it came to the topics of the receptors so thank you very much for taking your time out to do this.
Thanks for the explanation! I've noticed you said 'chromotropy'. Please note that it is 'chroNotropy'...it's about the tempo.
Thanks again!
Haha! You're right! Thanks so much!
hi joel,
so nicotinic receptors find themselves presynaptically for both adrenergic (SNS) and muscarinic (PNS) neurons. Why does nicotine (as far as i know) have a generally stimulating effect then? i understand it's because they trigger the adrenergic neurons, but do they not also trigger the muscarinic neurons?
+lou ovcm Well nicotinic receptors are only excitatory (muscarinic can be either excitatory or inhibitory) this is why they have a stimulating effect. And well, nicotine ONLY stimulates nicotinic receptors not the muscarinic ones.
Now yes, ACh stimulates both; however, you're asking about nicotine only. In this case it wouldn't affect the muscarinic.
hi, thank you for your answer. from what i understand, nicotinic receptors are found upstream of both the sympathetic (adrenergic) and parasympathetic (muscarinic) systems.
What I'm understanding, but may be wrong, is that both these systems require presynaptic nicotinic activation. so i understand that nicotine, binding to the nAChR upstream of the adrenergics will activate the sympathetic system, but I don't understand why the nicotine binding to the nAChR upstream of the muscarinics would also activate the parasympathetic.
+lou ovcm
hi i'm a just year 1 medical student so correct me if i'm wrong :) everything u said was correct and nicotine actually does stimulate both the SNS and PSNS. This is why smokers sometimes feel more active but in other times very relaxed depending on the extent of which nervous system was stimulated more. Did a little research and I think this is known as Nesbitt's paradox
+Jeremy Chan - Cool! I didn't know that! You da man!
you're a champ, thank you
just awesome......!!!!!!!how can u be so cool while explaining lecture....
It's easy. I wear sun glasses, a bath robe, and Nike sandals over my socks while listening to vanilla ice, and bobbing a pipe from my mouth.
After that, the "cool" just flows like a harpoon daily and nightly
as expected.....lol
Awesome video.
Thank you very much...!!!
Does muscarinic receptors are also found pre synaptically
I wish I found you earlier! You are the best! Thank you so much!
Amazing video, great job at simplifying some tough concepts.
very clear I'm really thank you +1
Dawale vaishnavi pandhari. Roll no :08
Thank you so much! I feel that seeing your videos is a good invest of time.
Best lecture ever...made things so easy👍👍
Great job! It's really easy to understand and memorise. Thanks a lot
You do a great job putting things together and making it make more sense! Thank you for your time building these videos!
You are very welcome!
Thank you dude you helped me a-lot
omg!! You should be my Pharm professor.
Again, really helpful!
thank you!! it provides simpler and more perspicuous explanation than my books
oanh phạm You're welcome Oanh!!
damn, you are better than any teacher i ever had..
This Veterinary student thanks you!!!
You're welcome Jacqueline! Good luck in school!
great put please what is your face book account I want to add you
+zuhair sniper
facebook.com/medimmersion/
twitter.com/MedImmersion/
th-cam.com/users/MedImmersion
+Med Immersion thank you sir
keep up that good work! Thanks so much
Great lecture, thanks for your help!
👏🏻👏🏻👏🏻
You must replace our professor!!
Great work!!
👍🏻👍🏻
Thanks Doctor ! :) You are the best :)
u r P E R F E C T
whats the link to print out the diagram
Ooops, I'll fix that asap. Thx Brittani!
this was very helpful thanx
salma ahmed You're welcome Salma.
its worthy of subscribe