Where is the blood pressure the highest
Blood Pressure in arteries is higher than in veins
blood pressure drops as blood gets
farther from the heart
the heart is a pump and so it does a
pump and then the blood has to go from
the heart all the way around the
circulatory system and back to the heart
again with the amount of pressure that
was pumped right here so pressure is
going to be highest at the moment of the
pump in the aorta and then pressure is
going to be very very lowest at the vena
cava so you can see that in our diagram
in our diagram on the y-axis we have
pressure in millimeters of mercury and
120 is typically the pressure that is
needed for the heart to be able to
successfully pump the blood all the way
around and then this bottom number 80 is
the pressure that is held in the pump or
in the ventricles of the heart even in
between heartbeats so use a red pen and
can write a Horta here obviously this is
going to be the highest pressure in the
body as far as blood pressure goes and
then it's going to start dropping so the
next I'm gonna actually turn the paper
sideways might be a little bit weird
that's not so bad you can see that right
so the large distributing arteries
those would be like the brachiocephalic
and the renal artery etc you can see
that pressure is dropping off a little
bit you still have a what's called a
pulse pressure that you could feel on
those arteries and then we get to the
arterioles here in that word holes at
the end this means little arteries and
the pulse pressure this little squiggly
line disappears by the end of the
arterioles
so by the time you get to the tiny
capillaries pressure has gone way down
and there is no pulse pressure so that's
good because that means blood flow is
always steady through the capillaries
then the capillaries drop off the oxygen
and other goodies at the tissue they
collect the waste product moist products
into veins you can use a blue pen there
and then last but not least the very
biggest vein in the body the vena cava
is going to have the lowest pressure and
in fact I'm gonna turn the paper again
if you look at what the pressure might
be in the vena cava it is so low we're
talking somewhere around three
millimeters of mercury and the
arterioles they typically start you
can't really I guess my picture is not
real great on that but the capillaries
are usually going to be about thirty
five millimeters of mercury and maybe
about fifteen by the time you get to the
end of the capillaries the arterioles
are going to be somewhere around 50
millimeters of mercury
and so we just see the steady drop as we
go through the blood system the
arterioles have the greatest impact on
blood pressure when they constrict
so when we talk about vasoconstriction
and vasodilation we're talking at the
arterial level allowing blood flow to go
to an organ or not and then another so
oh I wanted to say one more thing before
we end this page so if you are going to
be asked a question where is blood
pressure highest in the capillary or of
the vena cava you would say capillary
people tend to think oh a smaller blood
vessel lower blood pressure no that's
actually not the case it's the distance
from the heart so the aorta is the very
closest to the heart it has this great
high blood pressure and then it by the
time you get to the capillaries blood
pressure has gone down from let's say
120 to somewhere around I don't know 30
as it passes through you can see it's
dropping continually and then it
continues to drop so that you barely
have enough pressure to get the blood to
drop back in to the heart by the time
you've come all the way around you're as
far away from the heart as you'll get
and then coming back to it let's use a
green highlighter to highlight the pulse
pressure
oops sorry you couldn't see that so the
pulse pressure is the difference pulse
pressure difference between systolic and
diastolic values
