Hemodynamics

Question 1

most of the blood in our body is where

Answer 1

venous side

Question 2

vascular resistance is greatest at what level

Answer 2

arteriole level

Question 3

arteries vs. veins (which one is more compliant/distensible?)

Answer 3

veins

Question 4

distribute blood flow, control bp, exchange solutes/fluids

Answer 4

blood vessels

Question 5

collect fluid and proteins in interstitial spaces and return to circulation

Answer 5

lymphatics

Question 6

why is it important to maintain bp

Answer 6

so blood can perfuse and supply organs

Question 7

force exerted by the blood against the vessel wall

Answer 7

pressure

Question 8

diastolic - systolic pressure

Answer 8

pulse pressure

Question 9

refers to mean arterial pressure (MAP); dictates perfusion of the systemic organs

Answer 9

blood pressure

Question 10

CO x SVR=

Answer 10

blood pressure

Question 11

MAP=

Answer 11

DP + 1/3 PP
OR
(add twice the DP to the SP)/3

Question 12

normal MAP

Answer 12

85 mmHg

Question 13

increased arterial rigidity increases with what

Answer 13

age

Question 14

as we age, natural arterial sclerosis occurs and vessels become stiffer and less compliant causing and increase in what

Answer 14

BP
PP
SP

Question 15

when a person stands up, all the blood rushes to feet but what is maintained

Answer 15

perfusion gradient (organs are still getting their needed blood)

Question 16

total amount of fluid moving past a point over time

Answer 16

flow

Question 17

speed of fluid

Answer 17

velocity

Question 18

what happens when there is an increase in cross sectional area at site of capillaries

Answer 18

speed and pressure of blood slows down and resistance increases

Question 19

parabolic velocity profile of blood; blood travels fastest in the center (axial streaming)

Answer 19

laminar flow

Question 20

the drag between individual layers; increases with increasing amount of RBC’s

Answer 20

viscosity

Question 21

this is important for maintaining vascular homeostasis; makes it less likely for blood cells to stick to the vessel wall

Answer 21

shear stress profile

Question 22

where velocity increases, pressure falls

Answer 22

Bernoulli effect

Question 23

non-invasive way to measure blood flow and detect reduced perfusion; probe on skin detects sound wave from blood vessels

Answer 23

Doppler US

Question 24

invasive way of measuring blood flow that is used in surgery; 2 electrodes placed on vessel; measures emf of charged particles in blood

Answer 24

electromagnetic flowmeter

Question 25

2 main determinants of vascular resistance

Answer 25

vascular diameter blood viscosity

Question 26

important in controlling blood flow to organ beds and bp

Answer 26

vascular resistance

Question 27

how to calculate blood flow

Answer 27

Ohm's law: flow= change in pressure/resistance

Question 28

increase viscosity= increase in

Answer 28

resistance

Question 29

increase in diameter= decrease in

Answer 29

resistance

Question 30

small changes in arterial radius cause ______ changes in resistance

Answer 30

large changes (remember r^4)

Question 31

in a series circuit, where will pressure increase and decrease when resistance is applied (water hose)

Answer 31

pressure will decrease downstream and increase upstream of added resistance

Question 32

in parallel circuits, what is the distribution of pressure

Answer 32

the parallel branches all have the same pressure

Question 33

the whole network of vascular resistors can be reduced to what

Answer 33

a single resistor

Question 34

defined as a single resistance for the whole body (total resistance of entire systemic circulation)

Answer 34

systemic vascular resistance (SVR) or total peripheral resistance (TPR)

Question 35

amount of blood pumped out of heart per minute

Answer 35

cardiac output for the heart

Question 36

= stroke volume x HR

Answer 36

CO (heart)

Question 37

defined as total blood flow of the body

Answer 37

cardiac output (circulation)

Question 38

in circulation, cardiac output=

Answer 38

MAP/SVR mean arterial pressure/systemic vascular resistance

Question 39

increase SVR=

Answer 39

increase in arterial pressure

Question 40

constriction of 1 or few arterioles has what impact on MAP

Answer 40

little impact

Question 41

constriction of many arterioles has what impact on MAP

Answer 41

large impact

Question 42

Newtonian fluids (constant viscosity)

Answer 42

water and plasma

Question 43

viscosity variable (non-Newtonian); due to # of RBC's

Answer 43

whole blood

Question 44

can cause sludging and reduced flow

Answer 44

low net perfusion pressure (very low bp)

Question 45

aligning of RBC's in center of vessel can reduce what

Answer 45

viscosity

Question 46

main determinant of blood viscosity

Answer 46

hematocrit

Question 47

normal hematocrit % for males

Answer 47

45%

Question 48

normal hematocrit % for females

Answer 48

40%

Question 49

below normal hematocrit is known as

Answer 49

anemia

Question 50

why is 40-45% optimal hematocrit

Answer 50

because at the percentage, oxygen delivery is optimal

Question 51

control of vascular diameter is the primary mechanism for rapidly altering what in the body

Answer 51

resistance

Question 52

blood forced through a vessel too fast (no longer parabolic)

Answer 52

turbulent flow

Question 53

increasing velocity or decreasing viscosity can lead to what

Answer 53

turbulent flow

Question 54

determines if flow is turbulent; >2000

Answer 54

Reynold's number

Question 55

atheroslerotic plaques or coarctation and anemia can lead to what

Answer 55

turbulent flow (bruit)

Question 56

causes rushing sounds around affected valve (murmur)

Answer 56

Valvular stenosis or insufficency

Question 57

force acting to pull or tear open the vessel wall

Answer 57

wall tension

Question 58

tension= transmural pressure x _____

Answer 58

r (radius)

Question 59

wall tension is highest where

Answer 59

aorta

Question 60

high pressure and large diameter cause increase in what

Answer 60

wall tension