00:01
Autonomic Nervous
System Effectors.
00:05
Now, we get to talk
a lot about all this
different things that
happen throughout the body
that will able to
be doing something.
00:13
We are not just going to look at things,
we are going to look at action today.
00:20
The Autonomic Nervous
System is a large cohort
that’s controlling a number
of aspects of the body.
00:28
What we have here are
two different columns.
00:31
These are spinal cord columns.
00:34
The first one is the autonomic nervous
systems, sympathetic component.
00:39
And then, on the other side,
we have the parasympathetic component.
00:44
The sympathetic component
you know because it has
paravertebral chain ganglia on
both sides of the spinal cord.
00:53
This will act as relay
spots and sometimes where
the soma or cell body
of the nerve will be.
01:02
The parasympathetic
nervous system,
remember, primarily comes
from cranial nerve number 10.
01:09
So this vagus nerve will innervate many
of the different organs of the body.
01:14
These are the same organs
that would innervated
by those particular
sympathetic fibers
that come off of
the spinal cord.
01:22
In the parasympathetic nervous
system then you also have
the splanchnic nerve and some
that come from the sacral area.
01:29
And they will innervate things like
the bottom portion of the GI track,
places like the bladder and
the reproductive organs.
01:38
So we go through this process, I think
it’s best to do this one organ at a time.
01:44
And so, we do one organ, the next
organ, and keep going through those.
01:48
We’ll talk about what’s the
function that’s involve,
as well as what receptors will
mediate that particular function.
01:56
Let’s start off with the heart.
02:00
The heart is going to be
innovated by both the sympathetic
and parasympathetic
nervous system.
02:07
The SA node, and this is again the area
that’s going to control heart rate.
02:13
If it’s engage by the
sympathetic nervous system
it’s through Beta-1 (β1)
adrenergic receptors,
and this will
increase heart rate.
02:24
In contrast,
the parasympathetic nervous system,
is mediated through
muscarinic receptors
and that decreases heart rate.
02:35
The conduction system of the heart
especially around the AV node,
velocity can change
in response to
sympathetic comparison
sympathetic stimulation.
02:47
Beta-adrenergic receptors
here also increase
conduction velocity in the
sympathetic nervous system.
02:54
While muscarinic receptors,
this decrease the conduction velocity.
03:00
In terms of contractility, which is the
contraction, the strength of the heart,
this is gonna be mediated also
by beta-adrenergic receptors.
03:11
But now, this increases
contractility or an atrophy.
03:16
Muscarinic reflects don’t really have
anything to do with the ventricles,
to push blood around to
the body or to the lungs.
03:25
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.
03:37
So in the skin,
we mainly have alpha-adrenergic receptors
that cause vasoconstriction.
03:44
So vasoconstriction is
going to be decreasing
the luminal diameter
of a blood vessel
that reduces the
amount of blood flow.
03:54
Beta-2 (β2) adrenergic receptors
are located in skeletal muscle
and they can cause
a vasodilation.
04:02
That said, they are usually not
engaged in normal physiology.
04:06
You have to give us supra
physiological dose of a drug
to get this receptors
to be in acted.
04:13
So normally, our response
is having a vasoconstriction
in response the blood
vessels of skeletal muscle.
04:21
So you vasoconstrict them in terms of
the sympathetic nervous systems response.
04:26
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.
04:40
That’s said, there are some relaxing
factors that can be released.
04:45
And some of this have been associated
with some parasympathetic innervation
especially in the facial region.
04:52
The Autonomic Nervous
System and the Lung.
04:56
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.
05:06
If you dilated a bronchiole, what
will get is an increase in a diameter.
05:12
And if you have an increase in diameter,
you'll have a reduction and a resistance
and therefore more flow.
05:19
And this sympathetic nervous system
does just that by dilating bronchioles.
05:26
It does that through
beta-adrenergic receptors.
05:29
The opposite response
is a constriction.
05:32
And this is mediated by this
parasympathetic nervous system
through muscarinic receptors.