4.3.3 Flashcards
CHECK 699
what are venous sinuses
flatted veins with thin walls
coronary sinus and dural sinuses
how is backflow prevented in veins
valves ensuring one way flow
why do veins have such large lumens
to ensure blood returns to heart
how is blood pushed up hrough veins
SKELETAL MUSCLE CONTRACT
why do we have arterial anastomoses
for alternate pathways
where is arterial anastomoses commone
joints, brain, heart abdominal organ
unit measurement of blood flow
ml/min
5l/min
blood flow refers to
vessels
organs
entire circulation
all of the above
all of the above
blood flow is equivalent to -_______ for the entire vasucalr systesm
entire body movement
cardiac output
cardiac input
cardiac output
what is blood pressure
force per unit area exterted on the wall of a blood vessel
what is the unit measurement for BP
mm Hg
blood moves from ______ to ____ pressure
high to low
what does the resistance measure
amount of friction blood encounters
where is blood resistance encountered mostly
peripheral system circulation
what are the three important sources of resistance
blood viscosity (formed elements, plasma protein)
total blood vessel length (longer = more resistance)
blood vessel diameter (site of regulation)
main opportunity to change resistance is
diameter
if the radius is doubled, the resistance is
1/16
1/(radius)^4
what happens if a patient has fatty plaque from atherosclerosis
it dramatically increases resistance, disrupt laminar flow (turbulence)
if pressure gradient increases, blood flow will
speed up
slow down
stay the same
speed up
if resistance (R) increase blood flow will
speed up
slow down
stay the same
slow down
what is the most important influencer on blood flow
resistance b/c it easily changes by altering blood vessel diameter
how do we get pressure
flow is opposed by resistance
systemic pressure is highest in the
vena cava
peripheral system
aorta
left atrium
aorta
what is the pressure when blood is in the right atrium
0mm hg
when does the steeped drop in blood pressure occur
in the arterioles
what are the two factors that affect arterial blood pressure
elasticity
volume of blood forced into them
what is systolic pressure
pressure exerted during ventricul constriction
what is diastolic pressure
ventricular diastolis
how do you calculate pulse pressure
difference of systolic and diastolic pressure
what is the mean arterial pressure
pressure that propels blood to tissue
how to calculate MAP
diastolic pressure + 1/3 pulse pressure
what is the range for capillary blood pressure
15-35 mm Hg
what happens if capillaries had high BP
would rupture
is the change in venous BP little or large
little
what is the pressure gradient for venous BP
15 mm Hg
why is venous BP so low
cumulaitve effect of peripheral resistance
what 3 factors aid in blood return from veisn
respiratory pump
muscular pump and valves
vasconstriction under sympathetic contro;
