Okay so we’re back to that word, what
activates cholinergic activity in the lungs?
Well, remember which part we
asked you to circle - choline, right?p
So what activates the
cholinergic activity in the lungs?
Yep, there's the answer - acetylcholine.
so that's what makes it cholinergic activity,
it's because acetylcholine is the agonist,
That's the main ones
that makes things happen.
So acetylcholine is the substance
that makes cholinergic activity happen.
So acetylcholine activate cholinergic
and muscarinic receptors in the lungs.
Okay, I threw you a curveball,
right? I'll put another one in there.
Really I promise, it's straight forward.
Acetylcholine is the substance or an agonist.
Remember an agonist makes things happen, right?
It makes those receptors do what they're fired to do.
An antagonist will bind to the
receptor and block the action
but acetylcholine occurs in
your body and it is the substance
that activates both cholinergic and
muscarinic receptors in the lungs.
Now I'm going over that slowly
because it's important that you get it
and sometimes information comes
at you so fast, it's hard to process it.
So what makes a receptor cholinergic?
is if it is fired up or activated or by
acetylcholine, that's why we call it cholinergic
Now two types of receptors that are
cholinergic or activated by acetylcholine
are cholinergic - that one's
easy! and muscarinic receptors.
That one's a little harder to remember but since
we've make sure you make a special note of it
so it will make sense as we continue
moving through the rest of the section
Okay, so when the muscarinic receptors -
you might want to write that, muscarinic receptors
right above it, acetylcholine activates so when the muscarinic
receptors on the airway smooth muscle are activated,
the smooth muscle will cause bronchoconstriction.
Yes! all the work you just put in with me
from the beginning part of this pays off here,
so your brain already knows,
like oh, pffft this is easy.
Smooth muscle, I know where that is, that's in the
walls of the airway, that's around the airways,
so when these muscarinic receptors
are hit with acetylcholine, they're activated.
What's the job of a muscarinic
receptor in the airway?p
Well it's to makebronchoconstriction
happen by constricting the smooth muscle.
Now we already know that smooth muscle
is all over the body, right, in the hollow organs
but we're focusing in on this video right on
So cholinergic activity in the lungs, two types of receptors,
they're cholinergic receptors and muscarinic receptors.
Did you get that name? because
they're activated by acetylcholine.
So when the muscarinic receptors in
the airway smooth muscle activated,
that's when they cause broncoconstriction
meaning, "I can't breathe very well".
Okay, so muscarinic receptors, we got two types,
there's muscarinic receptors and nicotinic receptors.
Okay,woah! she's going rogue now,
no no no - I promise just stay with me.
So these cholinergic receptors that bind to
acetylcholine, we've got muscarinic and nicotinic.
Now in healthy lungs, muscarinic
receptors, said that one wrong, didn't I?
In your healthy lungs, muscarinic
receptors control smooth muscle tone, right?
They also control mucus secretion,
vasodilation, and inflammation
See it's really important that I slow down there
because I'm adding another layer to your understanding.
So you already know muscarinic
receptors are activated by acetylcholine.
In healthy lungs, muscarinic
receptors control smooth muscle tone.
Yeah, yeah, yeah - we already knew that part.
Okay, but they also do vasoconstriction,
vasodilation and inflammation.
Okay cool, so that makes sense that's why when we
look at those airways when they are all swollen,
that's because, look it's vasodilating.
That makes those tissues all swollen so the vasodilation, and
then it fills up with the gunk - that's the mucus secretion.
so that makes sense why when those muscarinic
receptors are activated and the normal control -
you have the smooth muscle control, the muscle tone right,
the mucus being secreted, vasodilation and inflammation.
When it is out of control, now its the airway you
look at that, it was all really too much of, and gunk
and tightening down of the muscles.
So in chronic obstructive pulmonary dosease and asthma,
the cholinergic mechanisms are the ones,they're responsible
for making the increased bronchoconstriction and
mucus secretions that's why it's hard to breathe.
Okay, one more time from the top as they say.
Okay so we've got muscarinic receptors, we're
focusing in on the muscarinic receptors that are
activated by acetylcholine in your
lungs right now, hopefully, you're not sick.
But in healthy lungs, muscarinic receptors do things
that are good, they control smooth muscle tone,
they control mucus secretion,
vasodilation and inflammation.
When it's out of control in one of
these diseases like asthma or COPD,
those same things are not in the approppriate
So, just like we talked about, you've
got muscle tone that clamped down,
you've got extra mucus, think of
it like trying to walk through Jell-O,
you've got extra vasodilation so those tissues are
really really swollen and you've got inflammation.
Now I want to hit that vasodilation point again.
Remember, have you ever like a, you got a cold
and you can't breath in your nose, you're like
"I can't breathe, I hate this. You can't eat,
can't sleep cause you can't breathe,
if I could just blow my nose, if I could just blow
my nose one time really good, I know I could breathe".
You blow, you blow, you blow
nothing comes out - what's the problem?
Well it's not mucus
It's because those tissues are vasodilated and they're all
swollen and that's what made your nasal passages smaller
Same thing happens in your airways, those
passages gets swollen from that vasodilation,
that's another reason why you can't breathe.
Okay, we've hung out a lot of time
here, talking about mucus and swollen
because I want you to have a crystal
clear picture of what goes on in these airways
and what it feels like to be that patient.
So now you know that this
is an airway out of control.
The normal things that happen in your airway
are now happening in an exaggerated extent
and that's why it's so difficult to breathe.
So back to our friend acetylcholine, remember
that's the one that activates muscarinic receptors.
So you got these parasympathetic nerves, they're the ones
that synthesize or they make and release acetylcholine
so were you're wondering where
this stuff came from? Now you know.
Acetylcholine is synthesized and released
by the parasympathetic nerves, okay?
They're the primary source
of acetylcholine in the lungs.
Okay, check! That's
important that you remember.
Where does this stuff come from?
Remember acetylcholine is not bad it's just in these
disease processes, it's out of control, alright?
We got too much of it.
So where does acetylcholine come from?
Wow, she repeats herself a lot.
Exactly, because I want you to do well on
your exams and to be an excellent nurse.
So where does acetylcholine come from?
We know the parasympathetic nerves
synthesize and release acetylcholine.
Okay good, you got the first point.
So acetylcholine can also be synthesized and released
by the epithelial and endothelial cells in the lungs.
Holy cow, you're like an acetylcholine factory.
So not only do the prasympathetic nerves do it,
also the epithelial and endothelial cells can do it.
Wow, that's the potential
for quite a bit of acetylcholine.
Remember that that acetylcholine,
we bolded that for you,
acts directly at the muscarinic
receptors on the airway smooth muscle
that's what causes the bronchoconstriction
and the mucus secretion in the airways.
So anticholinergics, here's the rescue.
Look at that word, anti-
always means against, right?
Anticholinergics are medications,
so they're against that acetylcholine.
Remember we talked about agonist, activator receptor.
Anticholinergics are antagonists.
They block the effects of acetylcholine
from the muscarinic receptors.
So those anticholinergics go racing, in
they connect to the muscarinic receptors
and you remember what the
muscarinic receptor's job is right?
It causes that smooth muscle
constriction and mucus secretion.
But if I have an anticholinergic medication there
at the receptor, acetylcholine might get produced
but it's all dressed up with no place to go
because the receptors' dance card is already full.
Right, the anticholinergic is on that
cholinergic receptor, on that muscarinic receptor
and so it takes acetylcholine connecting with the
receptor in order for that smooth muscle to constrict,
and the mucus to be created, got it?
We have a winner.
So now you know where acetylcholine comes from,
two places, acetylcholine comes from two places:
the parasympathetic nerves and it also comes from the
epithelial and the endothelial cells in the nerves.
Now what we can do to try to fix it is we
can give you an anti against cholinergic
so an anticholinergic will block acetylcholine's
access to that receptor and make all that happen.
So if I'm someone who has problems with my
airways being inflamed and making extra mucus,
if I take an anticholinergic, my airways
are gonna be less constricted, right?
because that smooth muscle's not going to clamp down
as much and I'm not gonna have as much mucus produced
as if I hadn't taken an anticholinergic medication.
There you go, you've done
great walking with me through that.