00:00
Now myasthenia gravis
is a lack of communication.
00:03
And we have some really cool pictures
to help you understand this.
00:08
So this is what it looks like normally.
00:11
And a patient with acetylcholine
and it's working the signal,
goes down to the receptors,
and the muscles contract and move.
00:17
In myasthenia gravis,
we've got a problem there.
00:21
The nerves aren't connecting
or communicating with the muscles
as they do in a normal setup,
so you end up with the paralysis.
00:30
Now don't worry, we're gonna break
that down a little bit more.
00:33
See, there's this error
in the transmission
of the nerve impulses
to the muscles.
00:38
Remember, that's what makes
our neuromuscular system neuromuscular.
00:43
It's the nerves and the muscles.
00:46
So when they aren't communicating well,
when the transmission
of the nerve impulse isn't working,
that's why the muscles aren't working.
00:53
Because that normal communication
just gets interrupted
at the neuromuscular junction.
00:58
Now I know I keep saying
those things slowly.
01:02
But sometimes we use words
we don't really think about what they mean.
01:05
That's what neuromuscular is.
01:07
We're talking about neuromuscular junction.
01:09
That's the little space
in between your nerves,
which you see represented up there
by the kind of yellowy form,
and the muscles,
kind of the more flesh colored there.
01:19
So when the communication
is interrupted
where the nerve cells connect
with the muscles that they control.
01:25
So neurotransmitters are these chemicals.
01:27
They communicate with the neurons.
01:30
That's how they send a message
from the nerves to the muscle
to tell it what to do.
01:34
So that's what communicates
the information.
01:36
Normally, when these electrical
signals or impulses,
these neurotransmitters
travel down a motor nerve.
01:42
The nerve endings release
this neurotransmitter called acetylcholine.
01:47
Okay, so look at our picture.
01:49
This is a normal nerve
and muscle connection and communication.
01:53
So those electrical signals
are traveling down that, right?
And it causes it to release
the acetylcholine
into the neuromuscular junction.
02:02
Now it will keep on progressing.
02:04
It's going to connect to those receptors,
the little green, almost tree-like things
with their arms out.
02:10
So the neurons will release
the acetylcholine.
02:14
It will travel down to the receptors.
02:16
So when acetylcholine travels
from the nerve ending
and it binds to the acetylcholine receptors
on the muscle,
then that action should cause
a contraction of the muscle,
allowing the patient to move it.
02:28
There is so much in our body
that is controlled
by transmitters and receptors.
02:34
This is just one more example.
02:36
In myasthenia gravis,
it got these antibodies.
02:40
There's this immune proteins
and they alter or destroy
the receptors for acetylcholine
at the neuromuscular junction.
02:46
So a neurotransmitter
without a functioning receptor,
it's not going to work.
02:52
That's where the problem is
and that's why the patient
experiences paralysis.
02:56
Most people with myasthenia gravis,
if it's caused by antibodies
to the acetylcholine receptor itself,
so their bodies have decided
to kind of attack
or block those actual
acetylcholine receptors.
03:09
Antibodies to other proteins like MuSK.
03:11
That sounds like a weird one, isn't it?
But it's muscle-specific kinase protein
can also lead to impaired transmission
at the neuromuscular junction.
03:19
Okay, so you don't need to memorize
a lot of different things.
03:23
We just want you to get the concept.
03:25
Acetylcholine, right?
Squirts out of that nerve
and its job is to attach
to acetylcholine receptor.
03:33
In autoimmune disease,
that patient's body is turned on itself,
and it started kind
of attacking those receptors,
so they're not workable.
03:40
That's why the patient is paralyzed.
03:43
So where do these nasty things
come from?
Where do antibodies come from?
Well, it's from their own system.
03:51
So the antibodies are good things.
03:52
We need those in our immune system
to protect us from most infections.
03:55
But in an autoimmune,
that means self-checking.
04:00
That's when we start to have a problem.
04:03
Myasthenia gravis
is an autoimmune disease
because the immune system,
which normally protects the body
from foreign organisms,
mistakenly attacks its own self.
04:13
Now we're going to talk about a gland
that we don't talk about a whole lot,
but it's the thymus gland.
04:19
That's the one that controls
the immune function
and we think it might be associated
with myasthenia gravis.
04:24
See, there's still a lot to learn
about myasthenia gravis,
but I'm gonna share with you
what we do know so far.