Neurotransmitters of the ANS - Video Tutorials & Practice Problems
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1
concept
Neurotransmitters of the ANS
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Hey, everyone. So now we're gonna dive into the neurotransmitters of our autonomic nervous system. So our A NS uses three neurotransmitters, acetylcholine, norepinephrine and epinephrine. You can see we have this table here and it's organized by division as well as pre and post ganglionic. So you can see what type of neurotransmitter, each of these fibers will be releasing. So if we start with the sympathetic division, you can see that our preganglionic fibers will be releasing acetylcholine. And then our post ganglionic fibers will be mostly releasing norepinephrine, also known as Nora adrenaline. And when I say mostly, I mean, about 80% of these fibers release this neurotransmitter. So this really is like the main neurotransmitter of this division. However, some of these fibers do release epinephrine, also known as adrenaline and a few release acetylcholine, although that is fairly rare. So just kind of keep that in mind. But norepinephrine is really kind of the big one. And then in our parasympathetic division, this one's kind of easy because both the pre and post ganglionic fibers just release acetylcholine. So when we're talking about these fibers, we're gonna be referring to them as cholinergic and adrenergic. So, a cholinergic fiber is a fiber that releases acetylcholine, which as I'm sure you can see based on our table, the majority of our fibers are going to be cholinergic fibers. So, cholinergic fibers include our sympathetic preganglionic fibers. They include our parasympathetic preganglionic fibers as well as our parasympathetic post ganglionic fibers. And I want to draw your attention to two things here. So the first is that the entire parasympathetic division is represented here. So all parasympathetic fibers are cholinergic fibers, they all release acetylcholine. And then also worth noting is that all of our preganglionic fibers are represented here. So within our autonomic nervous system, all preganglionic fibers are cholinergic, they all release acetylcholine. All right. So you can kind of think of cholinergic fibers as being kind of like the default fiber of our A NS. And then there's this one kind of pesky um exception to that, which are these adrenergic fibers which release nor um norepinephrine and epinephrine. And these are going to be our sympathetic post ganglionic fibers. Ok. So cholinergic is kind of our default and then adrenergic is kind of like the exception. So if we look at our image here, we have our sympathetic nervous system over here and our parasympathetic nervous system over here with the yellow and you can see like we talked about the majority of these fibers are red, they are mostly cholinergic, that's our default fiber. So you can see our entire parasympathetic division is represented here, both the pre and post ganglionic fibers here are all going to be cholinergic. And then you can see over on our sympathetic side, all of those preganglionic fibers are cholinergic as well. OK. And then we have this exception here, these blue fibers, these adrenergic fibers and this exception is actually fairly intuitive when you think about it though, because these are the fibers that are directly connecting our sympathetic division to our organs. And so it makes sense for them to be dumping um adrenaline and noradrenaline onto those organs because that's what's going to create that fight or flight response, right? And so you can see why we would want these blue fibers over here on the sympathetic side getting that fight or flight response going and we would not want any blue fibers anywhere else, right? We want to contain that epinephrine and norepinephrine and only use it when it's necessary. So that is why we have those um those blue fibers there on our sympathetic side. All right. So that is our intro to neurotransmitters and I will see you guys in our next video. Bye bye.
2
example
Neurotransmitters of the ANS Example 1
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1m
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OK. So for this one, we have this lovely depiction of dual innervation of the heart. And we're gonna be going through and labeling if these fibers are cholinergic, releasing acetylcholine or adrenergic, releasing norepinephrine or epinephrine. So, starting here in our sympathetic division with this preganglionic fiber. Remember all preganglionic fibers in our entire autonomic nervous system are always going to be cholinergic. So it has to be a cholinergic fiber and then you know what, while we're at it, let's go ahead and label this preganglionic fiber here on the parasympathetic side as well because it also has to be cholinergic. All right. So now jumping over here to the post ganglionic fiber on the sympathetic side. So this is gonna be the fiber that is directly communicating with the effector organs and to get that sympathetic activation, that fight or flight response going, we want to be putting some adrenaline into our system. So this is going to be an adrenergic fiber and then scooching over here to the postganglionic fiber on our parasympathetic side. Now, this is our rest and digest, right. So this does not want to be pumping any adrenaline into our body. This is going to be a cholinergic fiber as well. And you can see on our parasympathetic side, both of our fibers are gonna be cholinergic. So, pretty easy to remember that. So really just the one that's different is gonna be that post ganglionic sympathetic fiber and that's gonna be um an, an adrenergic fiber. All right. So there you have it and I'll see you in the next one. Bye bye.
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Problem
Problem
___________ and ___________ are the major neurotransmitters released by autonomic nervous system neurons.
A
Nicotine; muscarine.
B
Acetylcholine; norepinephrine.
C
Acetylcholine; serotonin.
D
Noradrenaline; adenosine.
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Problem
Problem
The neurotransmitter released at all synapses in the parasympathetic division is:
A
Serotonin.
B
Norepinephrine.
C
Epinephrine.
D
Acetylcholine.
5
concept
Neurotransmitter Receptors
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2m
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All right. So now we're gonna dive into neurotransmitter receptors. So, neurotransmitter receptors are just membrane receptors that are activated by neurotransmitters. And we can classify these receptors based on the neurotransmitter that they bind to. And within our A NS, there are two main types of neurotransmitter receptors. We have adrenergic receptors which bind to norepinephrine and epinephrine. And we have cholinergic receptors which bind to acetylcholine. Now, one very important subtype of cholinergic receptor is a nicotinic receptor. So, again, this is a subtype of cholinergic receptor. It's going to be responding to acetylcholine. And these are highly, highly abundant within our A NS. In fact, these are located at every syna between pre and post ganglionic fibers within the entire autonomic nervous system. Notably, these are also located in the adrenal medulla. What you guys remember is that sympathetic structure um located within the adrenal gland and this structure um is responsible for releasing epinephrine and norepinephrine. So, if we look down at our image here just to kind of orient you, we have our sympathetic division here on the left and our parasympathetic division here on the right. And you can see we have these little colored circles on each of our receptor sites. And you can see how some of them are grayed out. No spoilers. Those are for a future video. But then um looking here at all the ones in um green, those are all going to be our nicotinic receptors. So you can see how we have these nicotinic receptors um present again at literally every single preganglionic post gang leon synapse within our entire A NS. And that makes sense, right? Because remember these receptors respond to acetylcholine and all of our preganglionic fibers. Again, sympathetic and parasympathetic. All those preganglionic fibers are all cholinergic. So they're all gonna be releasing acetylcholine. So we have to have that receptor site that can of course bind to acetylcholine. Ok. So those are our nicotinic receptors, one of the most abundant types of um neurotransmitter receptors within our entire A NS. And I will see you guys in our next video to finish up talking about neurotransmitters. Bye bye.
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example
Neurotransmitters of the ANS Example 2
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1m
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All right. So this one asks us, where would you find a cholinergic nicotinic receptor? So, as a reminder, cholinergic receptors respond to acetylcholine, which is released by all preganglionic fibers in the entire autonomic nervous system. So we're gonna have those nicotinic receptors at the synapse between all preganglionic and post ganglionic fibers again in the entire A NS both sympathetic and parasympathetic. So based on that, our answer here is going to be D looking quickly at A through C. So A reads at a parasympathetic effector and those are gonna have cholinergic receptors, but they're not going to be nicotinic. We're actually gonna have a video on that coming up. So stay tuned for that. All right. And then C reads at a sympathetic effector, but those are going to be working with epinephrine and norepinephrine. So those need adrenergic receptors, right? And then b kind of a trick question because we don't have synapses between two preganglionic fibers, right? Um We synapse between a pre and a post ganglionic fiber. So our answer here is D and there you go
7
concept
Receptors at Target Organs
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2m
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We're gonna finish up this section by talking about a few more types of neurotransmitter receptors. So we're gonna begin with muscarinic receptors. Now, these are another type of cholinergic receptors. So they respond to acetyl choline. And these can be found at all parasympathetic target organs. And these are also present in the sympathetic system, but they're really only present at sweat glands. So they're not particularly prominent in that sympathetic division. Um They are really prominent in that parasympathetic system. And then we have our adrenergic receptors that respond of course to norepinephrine and epinephrine. And these will be very commonly found at sympathetic target organs. And we'll see that in the image in just one second. Now, there are two subtypes of adrenergic receptors. We have alpha receptors and beta receptors and there are subtypes of alpha and beta receptors as well. We're not gonna cover that in detail in this video but do make sure that you are aware of what your professor wants you to know. So scooching down to our image, you can see um we have all of these receptor sites, all these synapses now have highlights, we still have all of those green highlights. Those are our nicotinic receptors. You can see that those are present at all the synapses between pre and post ganglionic neurons there. And we're gonna start over here on the parasympathetic side, looking at all of these um yellow highlighted receptor sites and those are going to be where our muscarinic receptors are present. So remember those are a type of cholinergic receptor, they're going to be responding to acetylcholine. And of course, that makes sense because we have all of these little post ganglionic cholinergic fibers there that will be releasing acetylcholine into those synapses. So you can see all of our target organs on that parasympathetic side have those um muscarinic receptors there in yellow, looking at our sympathetic side, you can see we have these pinkish purple highlights on most of our sympathetic target organs and those are going to be our adrenergic receptors. And you can see we do have a couple of exceptions here. You can see on the skin, we have that muscarinic receptor. And then down here on the adrenal medulla, we have that nicotinic receptor. Like we talked about last time, you can see how the majority of these are going to be adrenergic. And of course, that makes sense because all of these adrenergic fibers, all these um post ganglionic adrenergic fibers are going to be releasing norepinephrine and epinephrine. So those target organs have to have receptors that can bind to those neurotransmitters. All right. So that is our section on neurotransmitters and I will see you guys in our next video. Bye bye.
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example
Neurotransmitters of the ANS Example 3
Video duration:
3m
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OK. It looks like for this one, we're gonna be filling in the blanks using the terms cholinergic adrenergic, nicotinic muscarinic beta, increased and decreased. So let's start here with our sympathetic activity up top. So first we have our preganglionic fiber and that is going to be a cholinergic fiber, right? All of our preganglionic fibers in the entire autonomic nervous system are cholinergic, they all release acetylcholine. So that's going to be a cholinergic fiber. And we can see that it is indeed releasing acetylcholine there. And then we're going to have our receptor right here and remember all of the receptors between our preganglionic and postganglionic fibers in the entire autonomic nervous system are nicotinic. So it has to be a nicotinic receptor. That's a subtype of a cholinergic receptor. So that is our nicotinic receptor. All right. And then we have our post ganglionic fiber. Now, in our sympathetic division, remember we want to be um getting those organs some adrenaline, right? Adrenaline or noradrenaline. And we can see that this one here is indeed releasing norepinephrine, no adrenaline. And so this has to be an adrenergic fiber. Ok. So that's our adrenergic fiber. It's releasing some no adrenaline. And then we have this receptor here. And in this case, this receptor is going to be a beta receptor. Remember that is a subtype of adrenergic receptor. And we see those on our sympathetic target organs. So we're gonna put beta here and here we are innervating the heart it looks like. And so with our sympathetic activity, we're going to have an increased heart rate. All right. So let's scooch down to our parasympathetic activity and we'll do the same thing. So, like we said, all of our preganglionic fibers and the entire A NS are cholinergic and this one is no exception. We can see it releasing acetylcholine there. So that is a cholinergic fiber. All right. And then we have that nicotinic receptor, same thing, right? All of our synapses between pre and post anionic fibers always have those nicotinic receptors. All right. And then in our parasympathetic division that post ganglionic fiber is also going to be cholinergic. We can see it releasing acetylcholine here. That is a cholinergic fiber. Remember we would not want to be releasing any um adrenaline or no adrenaline in this parasympathetic division, right? That would be very counterproductive. And then we have this receptor here and that is gonna be a type of cholinergic receptor. This is gonna be our muscarinic receptor. And remember these muscarinic receptors are found at all of our parasympathetic target organs. And so here with our parasympathetic activity, we're going to have a decreased heart rate. All right. So there you go. That is kind of a nice run through of um how we would label all of these fibers and all of these receptors and I will see you guys in our next video. Bye bye.
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Problem
Problem
What are the two types of receptors found in the parasympathetic system?
A
Cholinergic and adrenergic.
B
Nicotinic and muscarinic.
C
Nicotinic and alpha receptors.
D
Muscarinic and beta receptors.
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