systemic circulation Flashcards
in blood vessels, as volume increases what does pressure do?
increase
what is the compliance equation?
C= change in volume/change in transmural pressure
what is the elastance equation?
E= 1/C
= change in transmural pressure/change in volume
describe the structure of an artery
very round, thick wall, a lot of collagen, a lot of extracellular material
describe the structure of a vein
“floppy”, thin walled
can compliance be homeostatically regulated?
NO
about what is the compliance for the aorta?
~2mL/mmHg
about what is the compliance for veins?
100 mL/mmHg
arteries or veins, what does this statement describe
“small pressure changes have large volume changes”
describing the high compliance of veins
how much more volume do veins have than arteries?
about 3x
how much more distensible are veins than arteries?
8x
when will blood pressure drop to zero?
if blood volume dorps below 400 mL
veins or arteries; which has lower pressure?
veins
veins or arteries; which has higher blood volume?
veins
what happens to compliance as a person ages?
it decreases
what is 1 consequence of reduced compliance?
the heart must work harder to pump blood through stiffer vessels
describe the windkessel effect
the aorta, pulmonary artery and their major branches store a volume of blood (and elastic energy) during systole and then deliver the blood to the periphery during diastole to maintain blood flow in the body
in systemic circulation what is one word that describes pressure on the arterial side?
pulsatile
where is the greatest pulse pressure?
left ventricle
what happens to pressure with increasing distance from the heart?
it decreases
what happens to pulse pressure with age?
increases
what happens to stroke volume with age?
goes up
why does the dicrotic notch (incisura) occur?
there is a reversal of pressure (ventricle pressure is lower than aortic pressure) causing a momentary reversal of blood flow which closes aortic valves and creases a transient increase in aortic pressure
the reversal of flow seen directly before the aortic valve closure is important for what?
perfusion of the coronary arteries
what is the equation for tension?
T= transmural pressure x radius
define tension
a force exerting its effect along the wall circumference and is often described as “the force that would pull apart a LONGITUDINAL slit in the wall”
how do blood vessels respond to pressure changes?
by expanding or contracting their vessel
or by increasing the opposing force by smooth muscle contraction
what is a possible consequence of increased tension
aneurism
without any sympathetic stimulation, at what pressure will flow completely stop?
~ 6mmHg
vasoconstriction in response to hemorrhage can do what?
mobilize blood from the venous reseve
a sympathetic response to hemorrhaging would do what to a compliance curve?
shift it to the left so that BP can be maintained at a lower volume
what is raynaud’s disorder?
Brief episodes of vasospasm (narrowing of the blood vessel diameter)
in raynaud’s disorder what commonly triggers the vasospasms?
cold temperature or emotional stress
what is the typical sequence of a reynaud’s attack
digits first turn white (ischemia), blue (deoxygenation) then red (reprofusion). After it subsides, blood flow can return but can be with discomfort
