CARDIO PHYSIO Flashcards
what is flow directly proportional to? indirectly?
pressure
resistance
how do we define the CO?
total amount of blood flow out of the left ventricle per minute which is the amount of blood pumped per minute by the right ventricle and equal to venous return
T/F, CV is a closed or open system?
closed
what is the equation for CO? how much does the healthy resting adult heart pump?
stoke volume x heart rate
4.9 L/min
what is the equation for stroke volume?
EDV-ESV
120mL-50mL=70 mL
* 50mL is amount left in the ventricle
what is the average drop in pressure per liter of flow in systemic circulation?
19 mm Hg
affect of increased preload?
increase SV, increase CO
affect of increased afterload?
decrease SV, decrease CO
affect of resistance on increase in viscosity, increase in length of tube, increase radius of tube?
increase resistance
increase resistance
decrease resistance
what is the affect of more vascular beds in parallel on resistance?
decrease resistances and so less work for the heart and lower pressure for same CO
what is the difference in velocity and volume of blood?
units and definition
volume mLs/min
velocity meters/sec
volume of flow is in reference to amount of blood and velocity is speed of the blood
what is velocity a function of?
total cross sectional area for vessel types
velocity in aorta is less or more than capillary? if so, by how much or less? what about the aorta compared to the vena cava?
yes, 1000x
3x greater
when do you read diastolic pressure?
when you stop hearing sound when using a blood pressure cuff
what are the blood volume (young man, 65 y/o male) and distribution (heart, systemic circulation)?
6 L
5 L
heart 7% systemic circ 84% -veins 64% -arteries 13% -caps and arterioles 7% pulmonary 9%
how does the increase in pressure increase the flow? 2 ways
increase change in pressure
increase radius
veins are how many times more distensible than arteries?
8x
why is it much more difficult to have increase arterial pressure in the pulmonary system?
b/c is decreases the tendency to form edema in the lungs
what is compliance?
measure of adaptability of a vessel in terms of how much blood it holds with increase pressure which is a change in volume with a change in pressure
distensibility?
stretch dealing with cross sectional area
a systemic vein is how much more distensible than an artery and contracts how much blood compared to it?1
8 times
3 times
what are the effects of sympathetics on the heart?
why is this important
vasoconstrictor veins
decrease distensibility and compliance
increase venous return leading to increase EDV
increase stroke volume and increase cardiac output
its important to the body’s rapid response to severe blood loss or exercise
what is the effect of the parasympathetic on the blood vessels?
vasodilate to decrease venous return
what is the effect of vessels that are less distensible?
increase pulse pressure and peak systolic pressure increases to 160 mmHg and more
what is pressure proportional too?
pressure x radius, leading to more stretching
what happens when a weakened portion of a vessel is more easily stretched? what is a known syndrome that can cause this?
increased radius and tension leading developing an aneurysm
marfans syndrome
- weak collagen
- aneurysm
- rupture
- death
what is CVP?
near zero as long as the right atrium doesn’t accumulate blood, so the right atrial blood stays low as long as the right ventricle pumps well
what increases CVP?
increase venous return due to increase blood volume, venous constriction, arterial dilation
decrease right ventricular pumping
what can cause venous return decrease?
hemorrhage due to negative pressure because of negative intrapleural pressure inside chest
what is the effect of leg muscles contracting?
help to push blood upward through valves in the venous side and so if no contraction you increase pooling, decrease pooling return and so fainting occurs
