This content provides an introductory overview of the autonomic nervous system (ANS), differentiating it from the somatic nervous system and outlining its two primary branches: the sympathetic and parasympathetic nervous systems, including their origins and structural differences.
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I ninja nerds in this video we're going
to talk about the autonomic nervous
system so the autonomic nervous system
is extremely extremely important okay
so what we're gonna do is before we even
start getting into the nitty-gritty
parasympathetic and sympathetic and
enteric I want to talk about what
exactly the branches are that actually
make up the autonomic nervous system so
for example if we come over here real
quick when we talk about the divisions
of the nervous system you know there's
the central nervous system which is the
brain and the spinal cord and then
there's the peripheral nervous system
the peripheral nervous system is broken
into two systems right a sensory system
and a motor system
alright the motor system what we can do
is is we can actually break that into
two parts one it's called somatic motor
which is a part of your somatic nervous
system okay and this one is under
voluntary control in other words if I
want to have my biceps break I contract
I have voluntary control over that right
so we call that stomata motor where is
my heart or my GI tract or other
different parts of my actual viscera
those aren't under voluntary control
thank goodness they're not they're under
involuntary control so the involuntary
control is a part of your visceral motor
they call this the Auto Nam ik nervous
system okay the autonomic nervous system
which means it stands by itself
okay now the autonomic nervous system
there's three traditional branches of it
okay most people know it by the
sympathetic nervous system the
parasympathetic nervous system and the
last one most people don't consider it
they forget about this one but the
enteric nervous system the enteric
nervous system is another branch will
have a specific video focusing on this
in the GI physiology but for right now
we're gonna focus primarily on the
sympathetic nervous system in the
parasympathetic nervous system in this
video okay
all right so let's go ahead and talk
about the differences real quick
between the autonomic nervous system and
the somatic nervous I'm just very very
briefly all right so somatic nervous
system one of the big big differences
when we're talking about this is this
guy the somatic motor fibers it takes
one motor neuron to reach its effect
your effector organ so this right here
is going to be representing the somatic
nervous system so what do I mean you see
this motor neuron right here they call
this an alpha motor neuron it only takes
one of these motor neurons to extend all
the way from the spinal cord you know
what part of the spinal cord
specifically it's in with the anterior
gray Horn of the spinal cord okay so the
anterior or ventral gray Horn of the
spinal cord this alpha motor neuron
comes out and this alpha motor neuron
will come to an effect or work and
usually your skeletal muscles and it
will release a specific chemical that
acts on this effector tissue
do you know what that chemical is called
it's called acetylcholine okay an
acetylcholine whenever it's released on
this target tissue will act on specific
receptors that we'll talk about in other
videos which is going to be called a
nicotinic receptor alright nicotinic M
receptors for muscular system so they're
going to cause the contraction of that
actual skeletal muscle now
differentiating the somatic versus the
autonomic we have to remember that the
autonomic nervous system and again we're
only specifically in this video talking
about the sympathetic and the
parasympathetic okay
the autonomic nervous system takes two
motor neurons to reach their effector organ
organ
okay we call the first one the first one
which is coming out from the spinal cord
or coming from the brainstem because you
have cranial nerves that actually
actually act as automatic automatic
nerves this first one is called a pre
ganglionic and this next one afterwards
is going to be called a post
ganglionic motor neuron but we just want
to for right now we're not going to go
into the big big differences here I just
want us to understand that the
preganglionic motor neurons are gonna be
the ones that are coming out of the
spinal cord or they're going to be
coming from the actual brainstem the
postganglionic motor neurons are usually
going to be going to the effect organ
and we'll talk about specific ganglia
afterwards not right now okay so now we
have the basic difference between the
somatic nervous system and the autonomic
big difference is one motor neuron to
reach the effector organ autonomic takes
two motor neurons to reach the effector
organ first one is the preganglionic the
next one is the postganglionic we'll go
into more detail on these after let's go
ahead first
and focus on the sympathetic then we'll
talk about the parasympathetic okay so
the sympathetic nervous system what is
it for what's its purpose you probably
might have heard it is a the fight or
flight or fright stage right it's
designed to be able to use energy it's
used in stressful situations right or in
many different types of situations I
like to think about it is like you're
running away from some dangerous animal
like an orangutan
alright what's gonna happen we'll talk
about that in the individual video but
for right now we need an intro of where
you're gonna find the sympathetic
nervous system within the spinal cord so
this is a specific part of the spinal
cord and it extends all the way down
from t1 from your t1 vertebrae down to
about l2 this is the part of the spinal
cord from t1 all the way down to l2
there's a specific portion and this
portion is primarily where the
preganglionic cell bodies of the
autonomic nervous system specifically
the sympathetic are found and we'll talk
about where exactly after but from t1 to
okay because this is where the
sympathetic nervous systems coming out
this is where the preganglionic cell
bodies are located right here within the
t1 to l2 region and they're gonna come
out and they can go to different ganglia
and we'll talk about all that stuff
afterwards because we're going to talk
about each different type of splanchnic
nerve in an individual video on the
thoracic on the sympathetic nervous
system okay because these guys will go
to a post ganglionic motor neuron and
that'll go to the effector tissue okay
but we'll talk about this afterwards but
I just want you to get the basic
difference here is that the
thoracolumbar outflow is gonna be for
the sympathetic nervous system from t1
to l2
now the parasympathetic nervous system
where would you find that one exactly
the parasympathetic has different parts
within the spinal cord one part is
you're gonna have to remember it's
within the brainstem you know within the
brainstem you have the third cranial
nerve oculomotor nerve
well there's parasympathetic fibers that
move with the third cranial nerve and it
starts here at this nucleus called the
edding or Westfall nucleus and it comes
out here and supply specific structures
that we'll talk about individually in
the parasympathetic videos but it'll
come to some type of ganglion which
we'll talk about and this is mainly
gonna go and supply parts of the eye all
right but remember what nerve is this
this is cranial nerve three it moves
with and this is going to be
parasympathetic fibers so cranial nerve
three has parasympathetic input okay
what else you know here this blue
nucleus they call this the superior
salavat or nucleus the superior
Salvatori nucleus is going to be where
the preganglionic cell bodies are found
and they're gonna come out here as a
part of a specific nerve and it's just
called the facial nerve or cranial nerve
seven so cranial nerve seven is actually
going to have parasympathetic outflow
and it'll go to many different
structures we're not going to talk about
those target tissues now what else
another one is going to be right here
the inferior salivatory nucleus that's
going to be for the glossopharyngeal nerve
nerve
so the glossopharyngeal nerve is what
nerve this is going to be cranial nerve
nine and this is going to go to specific
tissues also and what's the last one
within the brainstem son-of-a-gun
the last one within the brainstem is
going to be the vagus and this is that
big Mambo Jambo this guy goes to so many
different tissues if you haven't watched
them already we've already made videos
that go into super super detail on all
the branches of cranial nerve 3 7 9 and
10 I suggest you guys watch those
because we're not going to go into a
whole bunch of detail in these videos
okay but this is going to be cranial
nerve 10 the vagus nerve and it goes
into specific tissues so we know cranial
nerve three seven nine and ten our
parasympathetic nerves what else down
here down here within the sacral region
of the spinal cord now there is
controversy in some textbooks they say
it's within the lateral horn in the
spinal cord they don't really say that
it's there there is books that will say
that there is technically no lateral
gray Horn of the spinal cord within the
sacral region but for right now we're
just going to say that it is within the
lateral part of the spinal cord but
specifically what part what level of the
spinal cord specifically around s 2 s 3
and s 4 this is one heck of an ugly s
let me fix that so s 2 s 3 and s 4 this
is going to be for our pelvic the pelvic
splanchnic serves we'll talk about that
ok but these are going to be going to a
bunch of target tissues also so what we
know is is that the parasympathetic is
made up of two portions the cranial
nerves 3 7 9 and 10 and the sacral
region s 2 s 3 S 4 so what do we call
that we call this cranial sacral outflow
okay so what are we gonna put it up here
here here here
alright so it's gonna be called the
cranial sacral outflow
okay and this is again made up of
cranial nerves 3 7 9 10 and s 2-4 okay
this is the cranial sacral outflow
alright so we know what levels of the
spinal cord you're gonna be seeing this
coming from thoracolumbar t1 l2
sympathetic parasympathetic granular 3 7
9 10 s2 s4 ok so we covered that we know
what regions of the spinal cord and
brain stem what I want to do now is I
want to zoom in on this thing that we
talked about the ganglia all right so
now if we come down here I want to talk
a little bit more about these autonomic
neurons ok I know we talked about pre
ganglionic and post ganglionic but I
want to get a little bit more into that
so now let's say that this top one up
here this one here this nice blue color
this is going to be our baby blue this
is the sympathetic nervous system we're
going to represent this one now there's
structural differences between the
parasympathetic and the sympathetic
nervous system they're certain their
axons their neurons the ones that are
coming out of the spinal cord this pre
ganglionic they're very short okay so
these pre ganglionic motor neurons
within the sympathetic nervous system
they are short okay
these ones over here the postganglionic
that we already termed and the
sympathetic nervous system they're going
to be long so they're short in the pre
ganglionic and long in the
postganglionic okay but in the
parasympathetic nervous system here in
this darker blue these are the pre
ganglionic so we already know that it's
just flipped so now the pre ganglionic
motor neurons are long and the
postganglionic motor neurons are short okay
okay
there's a reason why for this so
parasympathetic nervous system these
long pre ganglionic motor neurons they
travel and travel and travel until they
reach very very close
a target organ sometimes even within the
target organ so when we talk about these
ganglia first off how do we define a
ganglia a ganglia is just a group of
cell bodies that are located within the
peripheral nervous system that's all
they are so if you look I'm only drawing
one of these cell bodies but there's
multiple of them okay
multiple cell bodies within that ganglia
it's just a group of them now there's
only one specific type of ganglia in the
parasympathetic nervous system because
these preganglionic sar so long they
pretty much reach their effect organs
sometimes they go in there affect organ
so they call that terminal so they
sometimes refer to this one as a
terminal sometimes you might even hear
another synonym a terminal or you might
even hear the word intra mural ganglion
okay so for the parasympathetic nervous
system you're going to hear two
different terms one is you could find
what's called a terminal ganglion or you
can find an intramural ganglia it just
means that they're either at the target
organ or inside of the target organ
that's why these have to be long now for
the sympathetic it's a lot more
complicated unfortunately these you have
so many different types of ganglia and
that's what we're gonna go ahead and
talk about now because there is so many
of these okay
but before we do that actually let's
actually say one more thing about these
preganglionic and postganglionic
interaction when we look at the
sympathetic I want to zoom in real quick
on that synapse just zoom in real quick
on it so let's say that I zoom in on
this and I look at here's the axon
terminal and here's the cell body of
this postganglionic motor neuron I want
to know what type of chemical is being
released here at this ganglion this
presynaptic the postsynaptic interaction
generally this chemical that's going to
be released is going to be acetylcholine
and acetylcholine will come over and
stimulate this postganglionic motor
neuron okay so therefore we call this
fiber the preganglionic parasympathetic the
the
sympathetic fibers we call these
cholinergic fibers because they're
releasing acetylcholine then if i zoom
in here I look at the actual effector
tissue so now the possi angling ionic
motor neurons are gonna release a
specific neurotransmitter onto their
target tissue
what's that chemical that they release
it's not acetylcholine instead it's
called neuro epinephrine
so norepinephrine is released which will
act on the target tissue so pre
ganglionic sympathetic release
acetylcholine so they're cholinergic
postganglionic sympathetic released
norepinephrine so they're referred to as
adrenergic neurons
okay now parasympathetic if we zoom in
on that synapse there if we zoom in on
this synapse it's the exact same as the
sympathetic preganglionic so here's the
axon terminal here's the cell body when
they release a chemical they release
acetylcholine an acetylcholine
stimulates this postganglionic motor
neuron to fire if we zoom in on this one
here the postganglionic motor neuron to
the target tissue it still releases the
same thing acetylcholine so how would we
define this we would say that the
preganglionic sympathetic neurons are
cholinergic the sympathetic
postganglionic neurons are adrenergic
the parasympathetic preganglionic motor
neurons are cholinergic and the
parasympathetic postganglionic motor
neurons are cholinergic okay so
cholinergic cholinergic cholinergic
adrenergic now that we've done that
let's go ahead and zoom in now on the
different types of sympathetic ganglia
all right here's a nice big beast of a
diagram here right so we have to talk
about the different types of ganglia
within the sympathetic nervous system okay
okay
before we do that I want to talk about
where you're gonna find these cell
bodies of those preganglionic motor
neurons so we have a cross-section of a
spinal cord right
within the cross section you have the
anterior gray horn or the ventral gray
horn and you have the post your gray
horse or the dorsal gray or within the
thoracolumbar region member t1 to l2 you
have an intermediate lateral gray horn
okay an intermediate lateral gray horn
and right here is where you're going to
find the cell bodies of the
preganglionic sympathetic motor neurons
so for example here let's say i zoom in
on this guy that cell body is the
preganglionic step of that ik motor
neuron it can come out here right so we
know here's the preganglionic it can
move out through that with along with
the somatic fibers from the anterior
horn and it can move through the ventral
root when it goes to the ventral root it
can go out into the ventral ramus where
the spinal nerves are eventually form
right but there's something really cool
here what can happen is these
preganglionic sympathetic motor neurons
can actually move in to this little like
little sac of cell bodies here it can
move into this little like sack of cell
bodies what do they call that wonder
there's a group of cell bodies and the
pns it's a ganglia so there's gonna be a
whole bunch of cell bodies here so it's
called a ganglia but what is this one here
here
that's a ganglia oh what's this one down
here that's a ganglia what's this one up there
there
that's a ganglia all the ganglia are
connected in like a chain so what do you
think they call these ganglia they call
them Chang ganglia
so this ganglia right here is
specifically called there's many names
for these sons of guns you can call this
one a para vertebral you can also call
them if you don't want to call them pair
of vertebral you can also call them a
chain ganglia so you can call them pair
of vertebral ganglia or you can call
them the chain ganglia so whichever one
you guys prefer but again these
preganglionic sympathetic motor neurons
are coming out through the ventral
root all right and then as they do that
they go into the ventral ramus they come
through to this chain ganglia but how
what's this little tube right here
called that they move into it through
it's actually you know these pre
ganglionic motor neurons are very very
myelinated so because they're very very
very myelinated they show up as a white
matter okay so this is when you look at
this it's gonna look like a lot of white
matter so they call this the white ray
my community cans okay the white ray
might communicants now that's just the
actual pre ganglionic sympathetic motor
neurons their axons myelinated comes
into this chain ganglia where there's
gonna be a whole bunch of cell bodies
let's just draw a bunch of cell bodies
in here actually she's-- draw one for
the heck of it there's going to be the
cell bodies of the postganglionic motor
neurons now from here we're gonna go
through the 3 3 scenarios of where they
can go right if it comes here synapse is
on that cell body that post ganglionic
motor neuron that cell body and when it
does it axes it exits out through this
next little tube it goes out through
this other tube and then through the
ventral Ram is with the spinal nerve so
it goes with the ventral ramus as a part
of the spinal nerve and goes to three
different types of locations okay if it
does that tube right there this one here
is called the gray ray my communicants
now the question is why is it gray it's
because it's not myelinated so if it's
not myelinated it's gonna they're not
gonna have that myelin sheath so that's
why they call it gray ray might
communicate because it's unmyelinated
axons so now if this preganglionic goes
through the white ray of my community
can synapses on the cell bodies in this
chang ganglia or paravertebral ganglia
goes out through the grey ram i
communique as it enters into this
venture ramus with a spinal nerve this
is going to go to three different types
of tissues okay so now if it comes out
and goes to this action
smooth muscle tissue that's actually
found within the skin and it can
contract and pull our hairs up it's
called the erect or Li muscle so these
fibers are called pilo motor fibers
because it's going to the erector pili
throughout our entire body throughout
the entire level of the thoracolumbar
output okay it can also go to other
different regions it can go to the
actual blood vessels so we can actually
go to our blood vessels and cause the
vasoconstriction of our blood vessels so
if that's the case they call this
vasomotor fibers so I can go to our
blood vessels which are gonna be called
vasomotor fibers or it could go to
certain glands like sweat glands
throughout our entire body so they call
that pseudo motor okay so we can go to
sweat glands and this is one of the I
didn't mention it over there but there
is a couple exceptions to the
sympathetic postganglionic motor neurons
one of them is that sweat glands the
postganglionic sympathetic they don't
release norepinephrine they actually
release acetylcholine which is one of
the exceptions there's many exceptions
but this is one of them okay they'll
talk about another one which is actually
it doesn't actually act as a chain
ganglia doesn't act as a collateral
ganglia it actually goes straight to the
adrenal medulla which is actually gonna
be an example of an intramural ganglia
we'll talk about it as one more
exception okay so one type of ganglia is
the Chang ganglia or the pair of
vertebral ganglia they go through the
white out through the gray and they go a
part of a spinal nerve to the pilo motor
fibers vasomotor fibers or pseudo motor
fibers okay what's the next example
let's say that we take again what is
this over here our intermedia lateral
gray column right here and again what
are we gonna have here we're gonna have
two cell bodies of the preganglionic
sympathetic motor neurons they can come
out again these fibers are gonna still
going to be the same they're going to
come out through the ventral root when
they go out through the ventral root the
only thing it's gonna be a little
different is they're still gonna go
through the white ray my communicants
they're still going to go through this
white ray my communicants and they can
go in here and two things can happen right
right
so let's say that it decides that these
fibers when they come in it decides you
know what
I'm not gonna actually go through the
gray rain light communicants I want to
go down to another level so guess what
it does it says you know what I'm gonna
take and just go down another level of
the spinal cord so it decides to descend
down and that crazy so I can descend
down as it descends down it goes into
another ganglia it didn't synapse here
it just goes straight through the chain
ganglia and down to a level below that
part of the spinal cord when it does
that it then can go to an actual chain
ganglia and then it goes to this chain
ganglia it can synapse and then what can
happen here is it can actually still
move out through the gray array my
community cans and become a part of the
spinal nerve right and then go to the
erect or peel I again the the pile of
motor vasomotor or pseudo motor or you
know what else can happen it can
actually directly leave on its own it
doesn't even have to become a part of
the spinal nerve it just leaves it's its
own nerve you know what they call that
when things leave as their own nerve it
doesn't even go through any type of
nerve part it goes through its own this
right here is called a splanchnic
splanchnic nerve okay so what have we
seen here if they can go through the
white where in my community cans to a
Chang ganglia at that same level then
what can happen is it can go a level
down go to their synapse on these cell
bodies and maybe go out through the gray
or in my community cans and go to PI low
motor sudo motor vasomotor or it can
synapse on the cell bodies there these
postganglionic motor neurons and come
out as its own nerve that is called a
splanchnic nerve there's going to be a
good example of the ones in a thoracic
viscera that go to the heart the lungs
in the esophagus okay following off at
this blank Ticknor so I mean you might
be like oh I thought splain ignores have
to go to a collateral ganglia they do
but those are the ones that are going to
more of your abdominal viscera so for
example let's say I take
these fibers here they come through the
white rain my communicants they go into
the Chang ganglia they don't synapse
they're just like the ones that went
down instead they say you know what I'm
gonna go through this alternate tunnel
I'm gonna go down through this alternate
tunnel here and I'm gonna come here to
this ganglia that's located in front of
the vertebral column even in front of
that actually right around the aorta so
they actually call these ones because
they're in front of the aorta they're in
front of the vertebral column there's so
many names for these son of the guns if
you would look at these ones let's write
down all the different types they can
call them pre-k or Duke you know what
else they can call them pre vertebral
they can even call these guys collateral
ganglia and then for the last one you
can even call them because they're
beneath the diaphragm they're going to a
lot of the abdominal pelvic viscera
they're called sub diaphragmatic ganglia
ain't that crazy so there's so many
names for all of these darn ganglia here
ok so these are going to be the ganglia
of the autonomic nervous system that are
going to be going to a lot of your
abdominal pelvic viscera the splanchnic
nerves down there those are the ones
that are going down to the full racks so
if it does do this if it does synapse
here it can actually go through its own
little nerve again this little nerve
that's coming from the collateral
ganglia and going on its own this is a
splanchnic nerve but it's the splanchnic
nerves that are supplying the abdominal
viscera area so this is still a
splanchnic nerve and we'll talk about
the thoracic the lumbar and the sacral
endings in the sympathetic videos ok so
what do we have so far we have ones that
can go out at the level we can have ones
that descend at a level we have them
either go if they go down a level they
can go through the gray Rama or they can
come out as their own blanket nerve we
have ones that can actually pass right
through the Chang ganglia and go to a
collateral a pre vertebral a pre or DIC
a sub diaphragmatic
and go in their own nerve called a
splanchnic nerve what else well if it
can go down it can go up
alright so guess what these fibers let's
say that we take here this one was at
this level here it went down let's say
it goes up so if it goes up it can go in
ascend to a level and then from that
level it could either synapse on the
cell bodies here it might even go up
another level - sometimes you can go up
more than one level but it can ascend
and let's say that it ascends to this
level here and it synapses on cell
bodies right in this area what can
happen it could either go out as its own
spike Nick nurse it could either do what
go here out through the gray Ram light
communicants and become a part of the
pylon motor pseudo motor vasomotor
fibers so many different things that can
happen here okay so what we know about
the sympathetic ganglia is we have
paravertebral or chain they're the same
thing they're these trunks basically all
the way up and down and this can allow
for them to ascend descend or go out at
the same level pria aortic pre vertebral
collateral sub diaphragmatic means that
they go through the Y tre my
communicants they pass straight through
the Chang ganglia and go to another
ganglia these collateral preordered
subdiaphragmatic or pre vertebral and
then go out as their own splanchnic
nerve and then the last exception was
the one that supplies the thorax which
is going to be for acts and even some
parts of the head in the neck is it can
actually come through the Y train my
communicants right like if it happened
at this level I didn't show it here but
it could - so for example if I come down
here to this last part let's say here is
the intermediate lateral grey column it
comes over here comes out through the
ventral route through the ventral ramus
comes through the Y train like community
cans and synapses on the cell bodies
here the cell bodies could either go out
at that level or they could come as
their own splanchnic nerve all right so
I think that pretty much explains what
we need to know about the chain ganglia
okay guys so I hope you guys enjoyed
this video on the intro to the autonomic
nervous system what we're going to
in our next couple videos is we're gonna
talk a little bit more in detail on the
cranial sacral flow talking a little bit
more about those ganglia and muscarinic
and nicotinic receptors and then we'll
have one more video which is going to
focus on a little bit more detail on the
sympathetic nervous system talking about
those splanchnic nerves the different
gangland a little bit more detail and
then talking about the adrenergic
receptors okay alright engineers till
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