Okay, now we've talked about
the different nervous systems,
that's the first step in peripheral
nervous system understanding.
Now a neurotransmitter receptor is
the next piece that you wanna know.
See, a neurotransmitter receptor is a structure on a
cell's surface that binds to specific neurotransmitters.
That's why we call it a
So it's a receptor, it's on a cell surface
and it binds to specific neurotransmitters.
That's really a key.
It matters that only specific neurotransmitters
will fit only specific receptors.
Okay, so let's give you some examples,
cholinergic receptors bind to acetylcholine.
So look at the graphic
we have for you there.
The little green dot is acetylcholine,
that's what it represents.
The blue receptor you'll see is
shaped just like the green ball,
so they'll come together as a
cholinergic receptor and acetylcholine.
Now the easiest way to remember this
is look at we have choline in bold.
So underline that and then look in cholinergic
receptors, thank you, that's at least an easy way
to remember that what makes a cholinergic
receptor a cholinergic receptor,
is that it's mediated or it
turns on by acetylcholine.
Now, another type of receptor
are adrenergic receptors.
Now you'll see that these receptors
is kinda pie-shaped but up there,
we have three examples of receptors that
will also fit into adrenergic receptors.
So, they combine to norepinephrine,
dopamine or epinephrine
and you'll see we have those
letters up there for you.
Now, I know this might seem obvious
but take a minute and see,
would dopamine set off a
Nope, because it's
not specific to that
just like acetylcholine can't set off an
adrenergic receptor, it's not set up for that.
So a receptor is uniquely fitted
to certain neurotransmitters.
Dopamine, norepinephrine and
epinephrine go to adrenergic receptor.
Okay, let me give you
Now, I don't know if you've
ever gotten a mailer like this
but I get this in the mail all
the time from car dealerships.
It's a post card with
a key taped to it.
Now they're trying to draw
me into the car dealership
to get me to come down there so that
they can try and sell me a car.
So you get a post card like this, let
me show you how it ties into receptors.
This is like the key players in the analogy,
we couldn't avoid using that type of pun.
So, stay with me.
The ignition of a car and you have
the ignition with the key in it.
Now the ignition represent the receptor, it might
be cholinergic, that's mediated by acetylcholine.
It might be adrenergic, it could
be nicotinic or muscarinic.
Now we haven't talked about nicotinic
or muscarinic yet, we will.
But let's just, for the sake of discussion
right now, the ignition is like the receptor.
It has a unique fit to it, only
certain things will connect to it.
The key represents the transmitter like acetylcholine,
epinephrine, norepinephrine or dopamine.
So just for fun, quiz yourself.
What type of receptor does
Cool, I hope you said
What about epinephrine?
Awesome, those are adrenergic receptors
are mediated by epinephrine.
So you're in track in with us.
If you're not quite there, just stop for a
minute, go back and review those concepts.
The ignition represents the receptor and
only certain substances fit into it.
The key represents the transmitter like acetylcholine
for cholinergic, epinephrine for adrenergic.
Okay, now we have winner keys
and we call those agonists
and we have loser keys,
we call those antagonist.
Now let me explain to
you why we use those.
Okay, if a winner key is
inserted in the ignition,
I'm gonna put it in and turn it like
a car will start, I'm a winner.
That's what an agonist does.
An antagonist will fit in the ignition but it won't
let me start the car, that's why it's a loser.
So an agonist is a neurotransmitter or a drug that can
bind to the receptor and activate the receptor.
Remember, the winner key fit right into the
receptor of the ignition, I could turn it,
Voila! the car starts, I'm a winner, the engine
does what's it's supposed to do, it starts running.
An antagonist binds the receptor but
it doesn't activate the receptor.
Remember the loser key? if I put it in the
ignition, it won't start the car, right?
But also if I just left it there, it would prevent
the winner key from hitting that ignition,
that's what an antagonist does.
It binds to the receptor, so technically it
fits, but it doesn't activate the receptor
and it prevents any other agonist
from binding to the receptor.
Now this is really useful in
peripheral nervous system, okay?
So we have have agonist and we have antagonist and we
have drugs that can do both purposes with our receptors.
We have drugs that will bind
to a receptor and make it go
and we have drugs that will bind to a receptor
and block the action of that receptor.