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Chapter 18 Flashcards

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1
Q

the study of blood moving

through the circulatory system

A

Hemodynamics

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2
Q

_ indicates the volume of

blood moving during a particular time

A

Flow (volume flow rate)

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3
Q

_ answers the question: How much?

A

Flow

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4
Q

Units for flow

A

voulme/time (L/min)

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5
Q

_ the speed or swiftness of a fluid moving

from one location to another

A

Velocity

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6
Q

Velocity answer the question:

A

How fast?

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7
Q

Units for velocity

A

distance/time (cm/s)

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8
Q

Flow patterns in normal vessels are _ and vary with _

A

extremely complex

location, time within the heart cycle, and exercise

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9
Q

Pathologic conditions create _

A

even more diversity in flow patterns

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10
Q

Three basic forms of blood flow:

A

Pulsatile
Phasic
Steady

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11
Q

_ flow – when blood moves at a variable
velocity. Blood accelerates and decelerates as a
result of cardiac contraction, commonly appears in
arterial circulation

A

Pulsatile

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12
Q

_ flow – blood moves with a variable velocity.
Blood accelerates and decelerates as a result of
respiration, often appears in venous circulation

A

Phasic

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13
Q

_ flow – occurs when a fluid moves at a constant
speed or velocity. Present in the venous circulation
when individuals stop breathing for a brief moment.

A

Steady

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14
Q

_ flow is when the
flow streamlines are
aligned and parallel.

A

Laminar

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15
Q

_ flow is characterized by layers of
blood that travel at
individual speeds

A

laminar

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16
Q

Laminar flow is commonly found in _

A

normal physiologic states

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17
Q

2 forms of laminar flow

A

Plug

Parabolic

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18
Q 
bullet-shaped 
profile. Velocity is highest in the 
center of the lumen, and 
gradually decreases to its 
minimum at the vessel wall.
A

Parabolic flow

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19
Q

Plug flow

A

all of the layers and
blood cells travel at the same
velocity

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20
Q

Plug flow and parabolic flow are both associated with

A

normal physiology

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21
Q

Silent flow

A

laminar flow

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22
Q

Turbulent flow is

characterized by

A 
chaotic 
flow patterns in many 
different directions at many 
different speeds. The 
streamlines are often 
obliterated.
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23
Q

small,
hurricane-like, swirling,
rotational patterns that
appear in turbulent flow

A

Eddy/vortex

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24
Q

Turbulent flow is often associated with

A

cardiovascular pathology
and elevated blood
velocities

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25
Q

_ flow may be seen downstream from a stenosis in a vessel

A

Turbulent

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26
Q

Turbulent flow converts _ into _

A

flow energy

other forms such as sound or vibration

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27
Q

sound associated with

turbulence

A

Murmur or bruit

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28
Q

tissue vibration associated with
turbulence, also described as a palpable
murmur

A

Thrill

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29
Q

The Reynold’s number is _

A

a unitless number that

predicts whether flow is laminar or turbulent.

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30
Q

Vessels with comparable Reynold’s numbers

exhibit

A

similar flow characteristics

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31
Q

Reynold’s numbers above 2000 indicate

A

turbulent flow

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32
Q

Reynold’s numbers under 1500 will have _ flow

A

laminar

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33
Q

Blood moves from regions of _ to _

A

higher energy

lower energy

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34
Q

energy is imparted to blood by _

A

the contraction of

the heart during systole.

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35
Q

Forms of energy associated with blood:

A

 Kinetic
 Pressure
 gravitational

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36
Q

_ energy: Associated with a moving object

A

Kinetic

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37
Q

Kinetic energy is determined by 2 factors:

A

 An object’s mass

 The speed at which it moves

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38
Q

Heavy/quickly moving objects have _ kinetic

energy

A

high

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39
Q

Light/slowly moving objects have _ kinetic

energy

A

low

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40
Q

Pressure Energy

A

A form of stored or potential energy. It is a major form of energy for circulating blood and creates flow by overcoming resistance

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41
Q

Potential energy has

A

he ability to perform work

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42
Q

Gravitational energy

A

A form of stored or potenetial energy that is associated with any elevated object.

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43
Q

All elevated objects have _

A

stored energy that can perform work

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44
Q

As blood flows through the circulation, energy is

lost in 3 ways:

A

 Viscous loss
 Frictional loss
 Inertial loss

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45
Q

Viscosity

A

the thickness of a fluid

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46
Q

The thicker the fluid the _ viscous it is

A

more

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47
Q

Viscosity is measured in units of

A

poise

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48
Q

More energy is lost with movement of _ viscosity fluids

A

high

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49
Q

Viscous loss is associated wit

A

blood overcoming its internal

stickiness

50
Q

Hematocrit

A

the percentage of blood made up of red

blood cells.

51
Q

Normal hematocrirt

A

aprrox. 45%

52
Q

Viscous energy loss is determined b

A

Hematocrit

53
Q

Frictional losses occur when

A

low energy is
converted to heat as one object rubs against
another

54
Q

exxample of frictional loss:

A

Blood sliding across vessel walls creates heat

55
Q

Inertial Energy Loss: Energy is lost when

A

the speed of a fluid changes, regardless

of whether the fluid accelerates or decelerates

56
Q

tendency of a fluid to resist changes in velocity

A

Inertia

57
Q

Inertial energy loss occurs during three events:

A

 Pulsatile flow
 Phasic flow
 Velocity changes at a stenosis (maximum velocity exists where
the vessel is narrowest and decreases as the blood flows out of
the stenosis into a vessel segment of normal diameter)

58
Q

a narrowing in the lumen of a vessel

A

Stenosis

59
Q

Stenosis may have these effects on blood flow:

A

[] Changes in direction as blood flows into and out of the narrow portion of the vessel
 Increased velocity within the stenosis (Velocity is the highest where the vessel is the narrowest)
 Turbulence downstream from the stenosis (post-stenotic turbulance)
 Eddy currents, vortices, may have bruit, murmur or thrill
 Pressure gradient across the stenosis (pressure downstream is lower than the pressure upstream)
 Conversion of pulsatile flow patterns to steady flow

60
Q

Effects of a stenosis

A
  • change in flow direction
  • increased velocity as vessel narrows
  • turbulence downstream from the stenosis
  • pressure gradient across the stenosis
  • loss of pulsatility
61
Q

Describes the relationship between velocity and

pressure in a moving fluid

A

Bernoullis principle

62
Q

Bernoullis principle s derived from

A

the principle of conservation of energy

63
Q

With steady flow, the sum of all forms of energy is _

A

the same everywhere

64
Q

Bernouliis principle: the sum of _ energy and _ energy remains constant

A

kinetic and pressure

65
Q

Bernoulli’s Principle: Where kinetic energy is the highest,

pressure energy will be _

A

the lowest and vise versa

66
Q

Pressure gradient =

A

flow x resistance

67
Q

Study of blood flow is complex due to

A

the elastic nature of
blood vessels, composition of blood, and pulsatile nature of
heart pumping

68
Q

Pressure gradient increases with _

A

an increase in flow or resistance

69
Q

Flow increases with

A

an increase in pressure gradient or a

decrease in resistance

70
Q

Ohms law

A

Voltage = current x resistance

71
Q

Electrical resistance is reported

A

ohms

72
Q

Resistance vessels are called

A

arterioles

73
Q

Fluids: pressure
Electricity:

A

voltage

74
Q

Fluids: flow
Electricity:

A

current

75
Q

Fluids: resistance
Electricity:

A

resistance (ohms)

76
Q

_ are thin-walled and

collapsible

A

veins

77
Q

During normal function,
veins have a _ pressure
and are _
expanded (_ shaped)

A

low
only partly
hourglass

78
Q

Veins are _ resistance vessels

A

low

79
Q

When venous flow increases
with exercise, the cross-
sectional shape of a vein
changes from_, to _, and then to _

A

hourglass
oval
round

80
Q

As veins become more round,

the resistance to flow_ which increases _

A

decreases

outflow toward the heart

81
Q

Hydrostatic pressure

A

Pressure related to the weight of blood pressing
on a vessel measured at a height above or
below heart level

82
Q

Units for hydrostatic pressure

A

mmHg

83
Q

Hydrostatic pressure is important when _

A

measuring blood pressure

84
Q

Pressures are accurately assessed when the

measurement is made at

A

heart level

85
Q

Measurement is too _ if measurement is made

below heart

A

high

86
Q

Measurement is too _ if measurement is made

above heart

A

low

87
Q

When a person is _, all
parts of the body are at the
same level as the heart

A

supine

88
Q

When a person is supine hydrostatic pressure is _

A

zero everywhere

89
Q

A pressure measured
anywhere on a supine patient
accurately represents_

A

true circulatory pressure

90
Q

Hydrostatic Pressure- standing: At heart level, the hydrostatic pressure is _

A

zero

91
Q

Hydrostatic pressure- standing: At locations below heart level, hydrostatic
pressure is _. The measured pressure will be _

A

positive

higher than true circulatory pressure

92
Q

Hydrostatic pressure- standing: At locations above the heart, hydrostatic pressure
is _. The measured pressure will be _

A

negative

lower than the true circulatory pressure

93
Q

Hydrostatic pressure- standing: measured pressure=

A

circulatory pressure + hydrostatic pressure

94
Q

hydrostatic pressure @ ankle

A

100 mmHg

95
Q

hydrostatic pressure @ knee

A

75 mmHg

96
Q

hydrostatic pressure @ waist

A

50 mmHg

97
Q

hydrostatic pressure @ mid chest

A

0 mmHg

98
Q

hydrostatic pressure @ top of head

A

-30 mmHg

99
Q

n normal individuals, respiration affects venous

flow for two reasons:

A

 The venous system is low pressure

 Muscles responsible for respiration alter pressures in the thorax and the abdomen

100
Q

Breathing affects two venous flows:

A

 Venous flow in the legs

 Venous return to the heart (compromises venous flow from the head, arms, and flow from the IVC to the heart)

101
Q

_ is the
muscle responsible for
breathing

A

the diaphragm

102
Q

the diaphragm is located between _ and _

A

thorax and abdomen

103
Q

During inspiration, the

diaphragm moves

A

downward

104
Q

During inspiration, the chest cavity _, creating _ in the chest

A

expands

negative pressure

105
Q

Negative thoracic pressure

creates

A

suction that increases

venous return to the heart

106
Q

Venous flow from the head,
arms, and vena cava _
during inspiration

A

increases

107
Q

During inspiration, the

diaphragm also

A

presses into the abdomen

108
Q

inspiration: Abdominal compression

increases _

A

abdominal pressure

109
Q

Inspiration: venous flow in the legs _

A

decreases

110
Q

During expiration, the

diaphragm moves _, _pressure in the chest

A

upward

increasing

111
Q

Expiration: Increased thoracic pressure
__(increases or reduces) venous return to the
heart.

A

reduces

112
Q

Venous flow from the head,
arms, and vena cava all
_ during expiration.

A

decrease

113
Q

During expiration, the
diaphragm _
the abdomen.

A

decompresses

114
Q

Expiration: _ in abdominal pressure

A

decrease

115
Q

Expiration: _ in venous flow from the legs

A

increase

116
Q 
Inspiration:
Diaphragm moves _
Thoracic pressure _
Abdominal pressure _
Venous return to the heart _
Venous flow in legs _
A 
downward toward the abdomen
decreases
increases
increases
decreases
117
Q 
Expiration:
Diaphragm moves _
Thoracic pressure _
Abdominal pressure _
Venous return to the heart _
Venous flow in legs _
A 
upward into the thorax
increases
decreases
decreases
increases
118
Q

Venous flow in the legs correlates with

A

movement of the diaphragm.

119
Q

Downward movement of diaphragm =

A

decreases

venous flow in the legs

120
Q

Upward movement of diaphragm =

A

ncreases

venous flow in the legs

121
Q

Changes in venous return to the heart are _ to those of venous flow in the legs

A

opposite

122
Q 
Valsalva _ (increases or decreases_ pressure in the thorax and 
reduces all venous flows
A

increases

Physics (25 decks)

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