Professor Terry Machen
ASUC Lecture Notes Online is the only
authorized note-taking service at UC Berkeley. Do
not share, copy or illegally distribute (electronically
or otherwise) these notes. Our student-run
program depends on your individual subscription
for its continued existence.
These notes are copyrighted by the University of California and are for your personal use only.
N O T
C O P Y
Sharing or copying these notes is illegal and could end note taking for this course.
Constriction of Arteriolar Smooth Muscle:
There are a number of figures that I will change just
a little as I go through. I will post them on the
website so that those of you who miss things can
catch up on bSpace.
Today we’ll talk about cardiovascular regulation.
Basically what that means is that I will be going
through the rest of the mechanisms for how blood
flow to the capillaries, arterioles, and so forth
maintains its proper balance to increase or decrease
the amount of flow when appropriate. I will first go
through a bunch of mechanisms and then regulation
of blood pressure. I will mention these equations
here that the GSIs will go over in discussion
Page 59 has to do with regulation of blood flow into
and out of arterioles through constriction and
dilation. The control of all this is sort of confusing
and hard to get it all in one place. I’ve tried to do
them on these next few slides. The arterioles in
general are regulated by sympathetic constriction
and dilation. The constriction is not uniform – it’s
not in all vessels. In general it causes constriction,
and you don’t need to remember the alpha receptor,
but there are exceptions. The exceptions are: the
brain, which isn’t really regulated much, but it is
regulated according to CO
content and blood pH.
Also, the coronary – blood flow to the heart,
skeletal muscle, and liver, goes in the opposite
direction. Instead of constricting, it dilates. If you
think about this in terms of fight or flight
emergency, what you want to do is increase blood
flow to the places where you will need to beat your
heart faster, your skeletal muscles are going to be
working, and your liver is going to be pumping out
glucose into the blood stream.
Then there are a few hormones that also cause
constriction, but we will ignore those for the time
being. I will mostly talk about sympathetic and
stimulation releases epinephrine (E)
and norepinephrine (NE), which cause the muscle,
heart, and liver to dilate.
stimulation can also cause dilation, in two ways. In
some vessels it causes a reduction in NE output
inhibits restriction. It increases dilation by
inhibiting restriction. Also, there is EDRF. ACh, the
parasympathetic neurotransmitter, can also cause
the release of nitric oxide and cause relaxation. This
doesn’t happen everywhere, but happens in at least
some blood vessels.
Another way to dilate the blood vessels is