Vascular Hemodynamics Review

Question 1

how does length of a vessel influence resistance?

Answer 1

if increases, resistance increases

Question 2

how does radius of vessel influence resistance?

Answer 2

if increases, resistance decreases…to the 4th power

Question 3

how does viscosity influence resistance of a vessel?

Answer 3

more viscosity means more resistance

Question 4

explain why pressure decreases as we travel from ventricles to arteries to arterioles and to capillaries?

Answer 4

because “resistors” in series summate and as blood encounters more and more resistance the pressure drops

Question 5

what vessels give most resistance? and what does this put them in control of?

Answer 5

arterioles because they are smaller with muscular walls

they are in charge of regulating systemic vascular resistance

Question 6

for cardiovascular resistance…resistance is equal to what?

Answer 6

the change in pressure divided by cardiac output

deltaP/Q

Question 7

is the systemic or pulmonary vascular resistance higher?

Answer 7

systemic…because pressure change is greater

Question 8

define compliance of a vessel

Answer 8

ability for a vessel to be distensible

Question 9

if you have decreased compliance of a vessel…you have what?

Answer 9

increased stiffness

Question 10

define the passive component of vessel compliance

Answer 10

the ECM like collagen and elastic fibers

Question 11

define the active component of vessel compliance

Answer 11

smooth muscle tone

Question 12

compliance is equal to what?

Answer 12

change in volume/change in pressure

Question 13

are veins or arteries more compliant? what does this lead to?

Answer 13

veins…means at a given volume of blood…there will be less pressure in veins than arteries…so veins store mor of our blood

Question 14

if you decrease the arterial and venous compliance via catecholamines…what happens to blood?

Answer 14

you get an increase venous return to the heart

Question 15

explain why shunting blood in one location does not lead to big changes in resistance of flow elsewhere?

Answer 15

resistance in parallel is related to inverted resistance so changes do not have a big effect on the overall resistance

Question 16

with coronary vessels, what metabolic changes lead to vessel changes?

Answer 16

high H+, high CO2, low O2 and adenosine

Question 17

how does pressure affect wall tension?

Answer 17

as pressure increases so does wall tension

Question 18

how does radius affect wall tension?

Answer 18

as radius increases so does wall tension

Question 19

how does wall thickness affect wall tension?

Answer 19

the thicker the wall the less the tension

Question 20

when we exercise, what increases in the heart to lead to more coronary supply?

Answer 20

nitric oxide increases