In today's video we will be looking at the role baroreceptors have in
maintaining our blood pressure. Welcome back my name is Tammy and this is NurseMinder
and on this channel we do everything nursing, so if you're new here
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Now in a previous video I talked about the three elements that are involved in
maintaining blood pressure and that is heart rate, stroke volume, and peripheral
resistance, and there are two systems that I would like to talk about in a series of
videos and today we're going to talk about baroreceptors and how they
also help us to maintain a safe blood pressure. Now that we've covered the
three factors of blood pressure: heart rate, stroke volume, and resistance, let's
look at the two mechanisms that are actually at play that are increasing and
decreasing those three factors. The first one I want to talk about is the
baroreceptors. Now these are, consider them to be pressure gauges, and they are
found right outside the heart - so as soon as that ventricle pumps out the blood -
remember that's our stroke volume - this baroreceptor will gauge how much
pressure there is pushing towards the body. There's another set that is also
feeding the brain. So if the brain is not recognizing its getting enough fluid,
oxygen, nutrition, then these baroreceptors will sense that pressure and then it will
send a signal to the brain. Now the brain has this reflex kind of Arc and there
are two things it will do: If the pressure is increased, there is too much
pressure, it will send a signal that will change the vessel size, so we're gonna
have vasodilation. It's going to get wide to decrease the amount of blood
coming back to the heart, so that will affect stroke volume. It will also
decrease the heart rate. Remember we had cardiac output,
cardiac output is equal to heart rate times stroke volume. Cardiac output is
related to pressure sensed by the baroreceptors and so if it's too high
then we're going to drop the heart rate and drop the amount of blood that's
being pumped out with each contraction. Similarity if the pressure is too low
such as when people are dehydrated, then it's going to say "I need more" so let's
shrink those vessels up, we're going to increase the amount of blood that comes
back to the heart and we're going to increase the heart rat so that my
cardiac output increases. Now there is a very particular part of the brain that
monitors this baroreceptor signal and that's called the medul. The medulla
sits just underneath the pons and it actually houses a thing called the
cardiovascular center. And it is the it is the part that's responsible for
changes in the vascular system to address differences in pressure. So now
if you have a patient that has a brain stem injury
it is quite potential that they may not be able to regulate their blood pressure.
Now you have likely felt the influence of the medulla in action if you have
ever been laying down for so long that when you get up - WHOA - you feel dizzy, you
need to grab on to the railing for a while because what's happened is all
your blood has whoosh, gravity takes it right down to your feet. And then the medulla
recognizes there's been a shift in blood pressure- or a shift in pressure in
the vascular system it's dropped drastically. So what's it going to do?
It's going to constrict those vessels to increase the blood flow back up and it's
going to increase the heart rate so that we can meet our cardiac output needs.
Thanks for watching. Stay hydrated and until next time make it a great
day!! :)