Hemodynamics

Front 1

______ in a fluid system is commonly expressed as some measurement of pressure.

Back 1

Force

Front 2

Units of force: _____ Units of pressure in physics: _____

Back 2

dynes.
dynes/cm2.

Front 3

pressure difference which is responsible for the flow of a fluid from one point to another (e.g., inflow pressure minus outflow pressure, or upstream pressure minus downstream pressure).

Back 3

Driving pressure:

Front 4

Pressure difference across the wall of a cardiac chamber or blood vessel.
a. I.e., inside pressure minus outside pressure.
b. Responsible for distending the chamber or vessel.

Back 4

Transmural pressure:

Front 5

the force resulting from the action of gravity on a continuous column of fluid.

Back 5

Hydrostatic pressure:

Front 6

hydrostatic pressure is defined as the product of these 3 quantities:
P =

Back 6

P = hρg.

h = height of column of fluid or blood
ρ (rho) = density of fluid or blood
g = gravitational constant (980 cm/sec2)

Front 7

______ is commonly the reference fluid

Back 7

Mercury

Front 8

1mm Hg = ______ dynes/cm2

Back 8

1,330

Front 9

_____ is sometimes used for low pressures:

Back 9

H2O

Front 10

1mm Hg = ____ cm H2O)

Back 10

1.36

Front 11

Gravity and posture will affect ______ pressures (e.g., in systemic arteries )

Back 11

transmural

Front 12

___________ in systemic vessels is not affected by posture, because gravity and hydrostatic pressure affect both arterial and venous pressures to the same extent, but in opposite directions, and the effects cancel out.

Back 12

Driving pressure

Front 13

The term “hydrostatic pressure” is also commonly used by some authors to refer to the ______________, compared to atmospheric pressure, at any level relative to the heart.

Back 13

blood pressure inside capillaries

Front 14

Even though not technically correct, this use of the term _________ refers to the total pressure (the sum of that due to the pumping action of the heart and any P = hρg due to gravity).

Back 14

“hydrostatic pressure” in capillaries

Front 15

Another way to think of it is that it is a _________, rather than a colloid osmotic pressure due to protein concentration.

Back 15

fluid pressure

Front 16

Approximate Normal
PRESSURE (mm Hg)of Right atrium

Back 16

0-5 (mean)

Front 17

Approximate Normal
PRESSURE (mm Hg)of Right ventricle

Back 17

25-30/0-5 *

* systolic/diastolic

Front 18

Approximate Normal
PRESSURE (mm Hg)of Pulmonary artery

Back 18

25-30/3-13 *

Front 19

Approximate Normal
PRESSURE (mm Hg)of Pulmonary artery wedge

Back 19

3-13 (mean)

Front 20

Approximate Normal
PRESSURE (mm Hg)of Left atrium

Back 20

3-13 (mean)

Front 21

Approximate Normal
PRESSURE (mm Hg)of Left ventricle

Back 21

120/3-13 *

Front 22

Approximate Normal
PRESSURE (mm Hg)of Aorta

Back 22

120/80 *

Front 23

Approximate Normal
PRESSURE (mm Hg)of Mean systemic arterial

Back 23

100

Front 24

Approximate Normal
PRESSURE (mm Hg)of Systemic capillary

Back 24

20-30

Front 25

Approximate Normal
PRESSURE (mm Hg)of Systemic venous

Back 25

5-15

Front 26

At each branch point between aorta and capillaries the cross-Sectional Area of each individual branch _______.

Back 26

decreases

Front 27

At each branch point between aorta and capillaries the _____ cross-Sectional Area of all branches at a given level ______

Back 27

total
increases

Front 28

At each point of vessel convergence between capillaries and vena cavae the CSA’s of ______ vessels _________

Back 28

individual
increase

Front 29

At each point of vessel convergence between capillaries and vena cavae the _____ CSA of all vessels at a given level _______

Back 29

total
decreases

Front 30

Total CSA is greatest at the level of the______ and ________

Back 30

capillaries
smallest venules

Front 31

Between aorta and capillaries, velocity progressively ______ .

Back 31

decreases

Front 32

Between capillaries and vena cavae, velocity progressively _______.

Back 32

increases

Front 33

Is the relationship between total CSA and velocity direct or inverse?

Back 33

direct?

Front 34

Blood pressure _______ progressively between aorta and vena cava because of resistance to flow in all vessels

Back 34

decreases

Front 35

The greatest decrease in pressure occurs as blood flows through the systemic ____ arteries and arterioles, which represent the greatest _____ resistance to flow.

Back 35

small
total

Front 36

Pulsations in pressure are normally lost by the end of the ______________. (Arteriolar dilation can result in pulsations in capillaries.)

Back 36

systemic arterioles

Front 37

Volume Distribution of Aorta + systemic arteries + arterioles

Back 37

11 %

Front 38

Volume Distribution of Systemic capillaries

Back 38

5 %

Front 39

Volume Distribution of Systemic venules + veins + vena cavae

Back 39

67 %

Front 40

Volume Distribution of Pulmonary vessels

Back 40

12 %

Front 41

Volume Distribution of Heart

Back 41

5 %

Front 42

Blood flow: more accurately, volume flow. Units are of ____/____.

Back 42

volume/time

Front 43

Velocity: more accurately, linear velocity; the rate of movement. Units are of ______/_____ .

Back 43

distance moved/time

Front 44

Relationships between flow (Q) and velocity (v) of the fluid in a tube of cross-sectional area (A):

Q =

(A) can be for one large tube or total area of small tubes in parallel.

Back 44

vA

Front 45

Explain why velocity of blood flow decreases progressively from aorta to capillaries.

Back 45

--

Front 46

________ energy of blood in motion is the sum of potential and kinetic energies, which result in pressures in the system.

Back 46

Total

Front 47

Potential energies represented by _______ (It is the pressure exerted at right angles to the flow of the fluid.)& _________

Back 47

Lateral pressure
Hydrostatic pressure

Front 48

Kinetic energy represented by:
Ek=
where ρ = density and v = linear velocity

Back 48

1/2 ρv2

Front 49

Assuming constant volume flow and negligible loss of energy due to friction, total fluid energy (E) in a short segment of a vessel or tube will remain _______.

Back 49

constant

Front 50

(Bernoulli’s principle)
E =

Back 50

P + 1/2 ρv2 + hρg = constant

Front 51

Driving pressure (Pi - Po): In a vessel of uniform radius and length,
Q ~ Pi - Po, where Pi = _____
Po = _________

Back 51

inflow pressure
outflow pressure

Front 52

The resultant of all factors which oppose flow

Back 52

Resistance (R)

Front 53

R =

Back 53

(Pi - Po) / Q

Front 54

Poiseuille’s Law:
Pressure-Flow Relationships in Distensible Blood Vessels
Q =

Back 54

[(Pi - Po) π r4] / ηL8
where
r = radius of the vessel
L = length of the vessel
η = viscosity of the fluid

Front 55

R=

Back 55

(Pi - Po)/Q = ηL8/r4 π = R

Front 56

R~1/r4 tells us that

Back 56

very small changes in vascular radius have profound effects on resistance to blood flow.

Front 57

R~L tells us that

Back 57

under physiological conditions vessel length does not usually vary significantly

Front 58

R~η tells us

Back 58

characteristics of the fluid directly affects resistance.

Front 59

Increased resistance _______ pressure upstream, and ________ pressure downstream, assuming output of the heart is unchanged.

Back 59

increases / decreases

Front 60

In the body, changes in blood vessel resistance are most important at the level of the _______ , and may cause simultaneous changes in upstream and downstream pressures and flow to downstream vessels.

Back 60

arterioles

Front 61

Total Peripheral Resistance (TPR); also called Systemic Vascular Resistance (SVR) is the total vascular resistance of the __________.

Back 61

systemic circulation

Front 62

TPR (SVR)=

Back 62

Pi-Po/Q = mean aortic Pressure - Right atrial pressure / cardiac output

Front 63

The greatest proportion of TPR (or SVR) is located within all of the ______________ of the systemic circulation.

Back 63

small arteries and arterioles

Front 64

Series resistances: _____ resistance is the sum of the individual resistances

Back 64

total

Front 65

R(T) =
total resistance =

Back 65

R 1 + R2 + R3, etc.

Front 66

____ is greater than any individual R in the series.

Back 66

R(T)

Front 67

The reciprocal of total resistance is the sum of the reciprocals of the individual resistances.

Back 67

Parallel resistances

Front 68

1/RT =

Back 68

1/R1 + 1/R2 + 1/R3 etc.

Front 69

RT is _____ than any one of the individual R’s arranged in parallel.

Back 69

less

Front 70

conductance (G) =

Back 70

1/R

Front 71

The entire systemic circulation is ______ with the entire pulmonary circulation.

Back 71

in series

Front 72

Splanchnic circulation: intestinal and hepatic capillaries are _____.

Back 72

in series

Front 73

Kidney: afferent and efferent arterioles are ______

Back 73

in series.

Front 74

_________ occurs when Parallel movement of adjacent fluid molecules forms a series of concentric cylinders within the tube.

Back 74

Laminar Flow (Streamline Flow)

Front 75

The lamina adjacent to the wall is stationary, and the velocity of each successive lamina _______ toward the tube’s center.

Back 75

increases

Front 76

_________ is due to friction between adjacent laminae

Back 76

Resistance

Front 77

occurs when parallel laminae are disrupted into swirling currents.

Back 77

Turbulent Flow

Front 78

With turbulence, Pi - Po (Δ P) is proportional to ___

Back 78

Q^2

Front 79

Reynolds number:
NR

Back 79

ρDv/η, where: ρ = density
D = tube diameter
v = mean velocity
η = viscosity

Front 80

When NR is less than 2000, flow will usually be _____.

Back 80

laminar

Front 81

When NR is greater than 3000, flow will usually be _______.

Back 81

turbulent

Front 82

_______ flow is silent, but ________ flow commonly produces sound audible to a physician.

Back 82

Laminar / turbulent

Front 83

______ flow can promote formation of thrombi.

Back 83

Turbulent

Front 84

a ratio of a given viscosity to that of H2O

Back 84

Relative Viscosity:

Front 85

Plasma: relative viscosity ~

Back 85

1.3

Front 86

Whole blood: relative viscosity depends upon _______,_______, & _______.

Back 86

hematocrit, vessel diameter, and flow rate.

Front 87

Relative Viscosity of Whole Blood is Directly Proportional to _______.

Back 87

Hematocrit

Front 88

lower than normal hematocrit.

Back 88

Anemia:

Front 89

higher than normal hematocrit.

Back 89

Polycythemia:

Front 90

In _______ , hematocrit and relative viscosity are lower than in larger vessels such as arteries and arterioles, venules and veins.

Back 90

capillaries

Front 91

Fahraeus-Lindqvist effect: relative viscosity of blood decreases in vessels less than _____ in diameter.

Back 91

200 μm

Front 92

______,______, & ______ are all less than 200 μm in diameter.

Back 92

Arterioles, capillaries and venules

Front 93

At high velocity erythrocytes tend to accumulate in the _______ portion of the vessel which results in less apparent viscosity and less resistance.

Back 93

center (axial)

Front 94

at low velocity, erythrocytes tend to aggregate into _______, tending to increase apparent viscosity and resistance. This consequence of a low-flow state is sometimes called “anomalous viscosity”.

Back 94

stacks (“rouleaux”)

Front 95

Precise mathematical application of Poiseuille’s Law assumes the walls of the tubes are _____.

Back 95

rigid

Front 96

When NR is greater than 3000, flow will usually be _______.

Back 96

turbulent

Front 97

When NR is greater than 3000, flow will usually be _______.

Back 97

turbulent

Front 98

_______ flow is silent, but ________ flow commonly produces sound audible to a physician.

Back 98

Laminar / turbulent

Front 99

_______ flow is silent, but ________ flow commonly produces sound audible to a physician.

Back 99

Laminar / turbulent

Front 100

______ flow can promote formation of thrombi.

Back 100

Turbulent

Front 101

______ flow can promote formation of thrombi.

Back 101

Turbulent

Front 102

a ratio of a given viscosity to that of H2O

Back 102

Relative Viscosity:

Front 103

a ratio of a given viscosity to that of H2O

Back 103

Relative Viscosity:

Front 104

Plasma: relative viscosity ~

Back 104

1.3

Front 105

Plasma: relative viscosity ~

Back 105

1.3

Front 106

Whole blood: relative viscosity depends upon _______,_______, & _______.

Back 106

hematocrit, vessel diameter, and flow rate.

Front 107

Whole blood: relative viscosity depends upon _______,_______, & _______.

Back 107

hematocrit, vessel diameter, and flow rate.

Front 108

Relative Viscosity of Whole Blood is Directly Proportional to _______.

Back 108

Hematocrit

Front 109

Relative Viscosity of Whole Blood is Directly Proportional to _______.

Back 109

Hematocrit

Front 110

lower than normal hematocrit.

Back 110

Anemia:

Front 111

lower than normal hematocrit.

Back 111

Anemia:

Front 112

higher than normal hematocrit.

Back 112

Polycythemia:

Front 113

higher than normal hematocrit.

Back 113

Polycythemia:

Front 114

In _______ , hematocrit and relative viscosity are lower than in larger vessels such as arteries and arterioles, venules and veins.

Back 114

capillaries

Front 115

In _______ , hematocrit and relative viscosity are lower than in larger vessels such as arteries and arterioles, venules and veins.

Back 115

capillaries

Front 116

Fahraeus-Lindqvist effect: relative viscosity of blood decreases in vessels less than _____ in diameter.

Back 116

200 μm

Front 117

Fahraeus-Lindqvist effect: relative viscosity of blood decreases in vessels less than _____ in diameter.

Back 117

200 μm

Front 118

______,______, & ______ are all less than 200 μm in diameter.

Back 118

Arterioles, capillaries and venules

Front 119

______,______, & ______ are all less than 200 μm in diameter.

Back 119

Arterioles, capillaries and venules

Front 120

At high velocity erythrocytes tend to accumulate in the _______ portion of the vessel which results in less apparent viscosity and less resistance.

Back 120

center (axial)

Front 121

At high velocity erythrocytes tend to accumulate in the _______ portion of the vessel which results in less apparent viscosity and less resistance.

Back 121

center (axial)

Front 122

at low velocity, erythrocytes tend to aggregate into _______, tending to increase apparent viscosity and resistance. This consequence of a low-flow state is sometimes called “anomalous viscosity”.

Back 122

stacks (“rouleaux”)

Front 123

at low velocity, erythrocytes tend to aggregate into _______, tending to increase apparent viscosity and resistance. This consequence of a low-flow state is sometimes called “anomalous viscosity”.

Back 123

stacks (“rouleaux”)

Front 124

Precise mathematical application of Poiseuille’s Law assumes the walls of the tubes are _____.

Back 124

rigid

Front 125

Precise mathematical application of Poiseuille’s Law assumes the walls of the tubes are _____.

Back 125

rigid

Front 126

The walls of blood vessels are ________

Back 126

distensible

Front 127

As transmural pressure increases, blood vessels are distended, therefore resulting in ______.

Back 127

larger radii

Front 128

As transmural pressure increases, resistance ______ and volume flow ______ more than would be observed in rigid tubes.

Back 128

decreases
increases

Front 129

These factors make the relationships between volume flow and driving pressure in distensible vessels ________ , rather than linear.

Back 129

curvilinear

Front 130

the concepts summarized by Poiseuille’s Law definitely can give us important ______ and ________ information about the relationships among driving pressure, volume flow, blood vessel dimensions, and blood viscosity.

Back 130

directional / qualitative