WEEK 4 - CARDIO Pt3 Flashcards
what point of blood pressure is systole and diastole?
systole: highest blood pressure point
diastole: lowest blood pressure point
what is happens to the atrial bp?
it never gets really low and remains at a pretty constant level as it is one of the most critical factors that the body regulates (it is prioritised).
what happens if the mean aterial pressure (MAP) falls?
you get not enough blood flow to the brain and extremeties.
what is MAP?
mean arterial pressure - a balance between the blood flowing in and out of arteries which is determined by how much blood is in the arteries.
what controls the blood flow out of arteries into capillaries?
resistance of arteries.
blood in/out determines:
pressure
increased resistance =
descrease in outflow
increased output =
increase in flow
what is the equation for aterial pressure?
arterial pressure = cardiac output x total peripheral resistance.
flow =
pressure/resistance
MAP =
cardiac output x total peripheral resistance
CO =
stroke volume (L/beat)[contraction strength] x heart rate (beats/min)[contraction speed]
what is the brain vs sa node’s role in the beating of the heart?
the sa node makes the heart beat, but the brain tells it to speed up or slow down.
whats the difference between efferent and afferent?
afferent input: from systems to monitor what is happening
efferent output: instructions from brain to systems
what are baroreceptors?
blood pressure sensors - they are strentch receptors, mostly in the aortic arch.
parasympathetic:
break - rest and digest
sympathetic:
accelorator - fight or flight
to bring blood pressure down:
less input using efferent output from vagus nerve through parasympathetic system.
wdoes the vagus nerve do?
connects brain to heart at SA and AV nodes.
to bring blood pressure up:
sympathetic system through sympathetic trunk ganglion into sympathetic cardiac nerves which interact directly with SA and AV nodes (SA contracts faster, AV pause shorter).
how does unidirectional flow happen?
because there is a difference in pressure between arteries and veins
out of the aorta:
the arteries branch into smaller ones that go to specific organs
what kind of pressure is the systemic system under?
high pressure (high in arteries, low in veins)
what kind of pressure is the pulmonary circuit under?
it is short so low resistance and low pressure
at rest blood comes out opf the heart:
and into organs in parallel (mostly stomach, kidneys, stomach, muscles)
what happens in light exercise?
increased blood flow, heart rate, stroke volume, caardiac output
with exercise what changes in blood flow to organs?
brain - same heart - more kidney - less abdominal - less skin - more (heat) other - less skeletal muscle - much more
what is the systemic circuit made of?
a bunch of mini cricuits in parallel with one another
how is MAP controlled during exercise?
increased cardiac output so total peripheral resistance needs to be reduced (MAP = CO x TPR)
what is TPR?
total periperal resistance - resistance of all vessels in the body to blood movement.
how is TPR changed in exercise?
it is increased in some vessels because some organs dont need as much blood
what controls resistance and regional flow?
resistance vessels - arterioles
what allows arterioles to control resistance?
surrounded by smooth muscle.
what is the resistance formula?
r = 1/r4 = 1/(.5d) 4
what is luminal radius?
the radius of the blood vessel
how do you make resistance higher
make the diameter of the vessel smaller
what is it called when veins get smaller or bigger?
vasoconstriction and vasodilation
what is the rule of 16?
when you change the diameter by 2, the blood flow changes x 16
what happens to blood flow when you double the diameter?
ml/min is x16
what are the three things that control vascular resistance?
- mechanical (response to force)
- neural (vascular sympathetic nerves)
- humoral (blood)
what %of blood is in veins? why?
64%, extra blood is stored in veins
pressure and volume arteries vs veins:
arteries - high pressure, low volume
veins - low pressure, high volume
which is more complient?
veins - their shape is easily chnged due to the volume.
what is the compliance formula?
change in volume/change in pressure
where is most of the blood in the veins? why?
small veins/venules (they are most complient)
what is survival value?
veins can quickly push more blood back to the heart for arteries when they loose blood to save the MAP from dropping.
what does vascular compliance and gravity mean? How is this managed?
blood is at risk of pooling to distal parts.
- valves
- tone of surrounding tissue makes the veins less complient and therefore stops pooling.
- skeletal msucle contracting increases venous return
how would low muscle tone impact someone in re blood?
they experience blood pooling and fainting because their muscle is not holding the structure of their veins so gravity pools the blood.
why does exercise increase blood flow speed?
skeletal muscle contracting increases venous return to the heart back through the circuits.
what is starling’s law of the heart?
the more blood put into the heart before contraction, the stronger the contraction will be.
why is starling’s law of the heart true?
the more blood, the more the heart tissue stretches, the further the actin and myosin filaments are stretched from each other, so when they contract, they are pulled further making the contraction more significant.
what happens to stroke volume and cardiac output when the baroreflex/tilt test is conducted?
they both descrease. There is less effects of gravity to combat.
