Now, we get to talk
a lot about all this
different things that
happen throughout the body
that will able to
be doing something.
We are not just going to look at things,
we are going to look at action today.
The Autonomic Nervous
System is a large cohort
that’s controlling a number
of aspects of the body.
What we have here are
two different columns.
These are spinal cord columns.
The first one is the autonomic nervous
systems, sympathetic component.
And then, on the other side,
we have the parasympathetic component.
The sympathetic component
you know because it has
paravertebral chain ganglia on
both sides of the spinal cord.
This will act as relay
spots and sometimes where
the soma or cell body
of the nerve will be.
remember, primarily comes
from cranial nerve number 10.
So this vagus nerve will innervate many
of the different organs of the body.
These are the same organs
that would innervated
by those particular
that come off of
the spinal cord.
In the parasympathetic nervous
system then you also have
the splanchnic nerve and some
that come from the sacral area.
And they will innervate things like
the bottom portion of the GI track,
places like the bladder and
the reproductive organs.
So we go through this process, I think
it’s best to do this one organ at a time.
And so, we do one organ, the next
organ, and keep going through those.
We’ll talk about what’s the
function that’s involve,
as well as what receptors will
mediate that particular function.
Let’s start off with the heart.
The heart is going to be
innovated by both the sympathetic
The SA node, and this is again the area
that’s going to control heart rate.
If it’s engage by the
sympathetic nervous system
it’s through Beta-1 (β1)
and this will
increase heart rate.
the parasympathetic nervous system,
is mediated through
and that decreases heart rate.
The conduction system of the heart
especially around the AV node,
velocity can change
in response to
here also increase
conduction velocity in the
sympathetic nervous system.
While muscarinic receptors,
this decrease the conduction velocity.
In terms of contractility, which is the
contraction, the strength of the heart,
this is gonna be mediated also
by beta-adrenergic receptors.
But now, this increases
contractility or an atrophy.
Muscarinic reflects don’t really have
anything to do with the ventricles,
to push blood around to
the body or to the lungs.
What happens to the blood flow that
goes to the skin in the muscle?
Here we need to talk through which
things cause constrictions and dilations.
So in the skin,
we mainly have alpha-adrenergic receptors
that cause vasoconstriction.
So vasoconstriction is
going to be decreasing
the luminal diameter
of a blood vessel
that reduces the
amount of blood flow.
Beta-2 (β2) adrenergic receptors
are located in skeletal muscle
and they can cause
That said, they are usually not
engaged in normal physiology.
You have to give us supra
physiological dose of a drug
to get this receptors
to be in acted.
So normally, our response
is having a vasoconstriction
in response the blood
vessels of skeletal muscle.
So you vasoconstrict them in terms of
the sympathetic nervous systems response.
Hopefully, you’ve looked now
on the parasympathetic side
and notice there is no
intervention of blood vessels
to the skin or to the muscle from
the parasympathetic nervous system.
That’s said, there are some relaxing
factors that can be released.
And some of this have been associated
with some parasympathetic innervation
especially in the facial region.
The Autonomic Nervous
System and the Lung.
So what changes happen
with the lung in regards
to a sympathetic and
parasympathetic nervous system?
The main component with the
lung are the bronchioles.
If you dilated a bronchiole, what
will get is an increase in a diameter.
And if you have an increase in diameter,
you'll have a reduction and a resistance
and therefore more flow.
And this sympathetic nervous system
does just that by dilating bronchioles.
It does that through
The opposite response
is a constriction.
And this is mediated by this
parasympathetic nervous system
through muscarinic receptors.