Arteries Veins Flashcards
all blood vessels are
distensible
blood vessels accommodate
pulsatile cardiac output
what does distensibility mean
how stretchy a vessel is
what is compliance
total quantity of blood that can be stored in a given potion of the circulation for each mm Hg pressure rise
a lot of compliance means
it can hold a lot without changing the pressure a lot
normal arterial pressure is about
100 mm Hg
how are arteries higher pressure when heart contracts
put more blood into arteries so BP goes up
why does BP fall in diastole in arteries
blood is going to tissues, so less blood in arteries
venous system holds a lot of blood at very low
pressure
we can change a lot of the amount of blood in veins without changing
pressure
arteries or veins more compliant?
venous system
how do we change compliance?
sympathetic stimulation
when sympathetic nerves release NE, what does it do to compliance
decreases of arteries and venous system
decreased compliance does what to BP
increases
change compliance of venous system and you change
venous return back to heart
if somebody has second degree heart block what happens to pressure
it decreases b/c volume decreases
artery has a lot more ____ than veins
elastic
what two things determine blood in arterial system
CO & peripheral resistance
if you don’t change resistance and you increase CO what happens to pressure
increase
if you don’t change resistance and you increase CO what happens to pressure why does it have to increase
putting more blood into system
increase peripheral resistance and CO stays the same what happens to pressure?
increase
arterial pressure formula
CO x total peripheral resistance = Arterial pressure
Cardiac output =
stroke volume x heart rate
pressure plse is called
pulse pressure
what is pulse pressure
systolic aortic pressure - diastolic aortic pressure
normally pulse pressure is around
40 mm /Hg
what factors affect pulse pressure
stoke volume & arterial compliance
increase in stroke volume will do what to pulse pressure
increase
valvular defect that increases pulse pressure
aortic regurgitation (pressure goes high, systolic .)
decrease in arterial compliance does what to pulse pressure
increase
decrease in arterial compliance means it is
less stretchy
look at pg 11
11
PDA what happens to pulse pressure
increases
PDA stands for
patent ductus arteriosus
what happens to diastolic pressure in PDA
low
aortic regurgitation what happens to pulse pressure
increases
what happens to diastolic pressure in aortic regurgitation
decrease
pulmonary regurgitation will not cause increase in
pulse pressure
in aortic stenosis what happens to pulse pressure
decreases
arteriosclerosis what happens to pulse pressure
increases
what is arteriosclerosis
hardening of arteries
why does hardening of arteries cause increase in pulse pressure
not compliant - they don’t stretch as well
what are you measuring when you feel a pulse
like throwing rock in water and seeing the wave
what happens to pulse pressures in smaller arteries, arterioles and capillaries
it gets less
pressure is pretty ____ in capillary
smooth, blood flow very uniform
why is BP measured at arm?
it’s about the same height as tricuspid valve
what is mean blood pressure
average blood pressure: systolic + diastolic / 2
if you increase HR how accurate is the MAP equation
less accurate
as you increase HR, the MAP formulas become
less accurate
natural ____ in BP over time
increase
as you age, what happens to BP
increases
veins are very
compliant
if you need more blood in arterial side, it gets it from where
venous side
venous system acts as ____ of blood
reservoir
if 60% of blood is normally in venous side, can change ____ of veins to shift more back to arterial system
compliance
how do you change compliance in veins
sympathetic control
right atrial pressure =
0
right atrial pressure = (not number)
central venous pressure
CVP stands for
central venous pressure
CVP is
basically the same as right atrial pressure
if right atrial pressure increases, ___ increases
CVP
what determines right atrial pressure
Ability of right ventricle to pump blood out of right atria.
Tendency for blood to return to right atrium (how much blood is returning)
normal RAP =
0
if RAP gets above 0, a health heart will
pump more strongly and get RAP back to 0
RAP stands for
right atrial pressure
if we decrease venous compliance where does blood go
to heart
if decreased compliance in venous system what happens to RAP
increased
increased blood volume does what to RAP
increased
if you lose blood (like hemmoraghing) what does it do to RAP
decrease
dilation of arterioles, what does that do to RAP
increase
hyperthyroidism what happens to vessels in body
dilate
person lying down has peripheral small vein pressure about
4-6 mmHg
at normal RAP the veins are
partially collapsed
as RAP is increased what happens to veins
they opena nd get bigger
anytime RAP is above 6 what happens to veins
they increase so they can bring the blood back to the heart
anything in abdominal cavity that pressures on vein causes venous pressures in legs to be
higher to overcome the resistance
anytime something is pressing on a vein, what happens to veins below it
pressures below the vein have to be greater to push it up
venous pressure in legs is ____ higher than pressure in heart
90 mm Hg
why is pressure in veins higher in feet than heart
gravitational weight of blood
anything above head, veins are usually
collapsed
why are veins above the head collapsed
atmospheric pressure
veins in skull can have
negative pressures
arterial pressure in feet can be as high as
190 mmHg
blood pressure in leg vs. arm
will be 90 higher in leg
why do your legs swell if you stand still
Increase in capillary pressure will cause fluid to move out from capillaries into interstitial space leading to swelling.
arterial pressure in feet vs in heart
higher in feet vs. heart
when you walk, why don’t your legs get swollen
muscles contract the veins and make the valves work so that the blood doesn’t get stuck in legs
one indictation that venous pressures are high
jugular vein distension
why do you measure BP in arm
at level of tricuspid valve
level of tricuspid valve is about
0 point in body - why we measure BP there
if you lose blood, like in hemorrhage, what happens to compliance of veins
decreased compliance to bring blood back to heat
what is a very important role in regard to hemorrhage
veins
what is the major blood reservoir in body
veins
