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Ultrasound Physics > CH 18 - Hemodynamics > Flashcards

CH 18 - Hemodynamics Flashcards

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1
Q

the study of blood moving through the circulatory system

A

hemodynamics

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2
Q

flow / volume flow rate

A

indicates the volume of blood moving during a particular time
units - L/min

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3
Q

velocity

A

speed of a fluid moving from one location to another

units - cm/s

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4
Q

three basic forms of blood flow

A

pulsatile
phasic
steady

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5
Q

type of flow that occurs when blood moves with a variable velocity

A

pulsatile flow

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6
Q

blood has a variable velocity because of

A

cardiac contraction

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7
Q

pulsatile flow commonly appears in the ___ circulation

A

arterial

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8
Q

this type of flow also occurs when blood moves with a variable velocity, but because of respirations

A

phasic flow

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9
Q

phasic flow often appears in ___ circulation

A

venous

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10
Q

occurs when a fluid moves at a constant speed or velocity

A

steady flow

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11
Q

steady flow is present in the venous circulation when ___

A

individuals stop breathing for a brief moment

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12
Q

when the flow streamlines are aligned and parallel

A

laminar flow

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13
Q

laminar flow is characterized by layers of blood that travel at …

A

individual speeds

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14
Q

laminar flow patterns are normal or abnormal

A

normal

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15
Q

laminar flow has 2 terms

A

plug flow

parabolic flow

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16
Q

occurs when all of the layers of blood cells travel at the same velocity

A

plug flow

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17
Q

parabolic flow

A

bullet shaped profile

velocity is highest in the center of the lumen and gradually decreases at the walls of the vessel

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18
Q

Reynolds number

A

predicts whether flow is laminar or turbulent

laminar is less than 1500

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19
Q

flow that is characterized by chaotic flow patterns in many different directions and many speeds

A

turbulent flow

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20
Q

turbulence is often associated with a ___

A

pathology

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21
Q

sound associated with a turbulence

A

murmur

bruit

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22
Q

vibration associated with turbulence

A

thrill

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23
Q

a palpable murmur that you can feel with your fingertips

A

thrill

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24
Q

Reynolds number of turbulent flow

A

greater than 2000

25
Q

why does blood move from one location to another

A

energy gradient - moves from high to low energy

26
Q

what event provides energy to the circulating blood

A

systole

27
Q

forms of energy in blood

A

kinetic
pressure
gravity

28
Q

kinetic energy is associated with a moving object

has 2 factors

A

an objects mass (high mass, high kinetic energy)

the speed at which it moves (high speed, high kinetic energy)

29
Q

pressure energy is a form of ___ or ___ energy

A

stored or potential energy

30
Q

a form of stored or potential energy associated with any elevated object

A

gravitational energy

31
Q

energy is lost in 3 ways in curculation

A

viscous loss
frictional loss
inertial loss

32
Q

the thickness of a fluid

A

viscosity

33
Q

viscosity units

A

Poise

34
Q

the percentage of blood made up of red blood cells

A

hematocrit

35
Q

how do we determine viscous energy loss in blood

A

hematocrit

36
Q

normal hematocrit level

A

45%

37
Q

occurs when flow energy is converted to heat as one object rubs against another

A

frictional energy loss

38
Q

energy loss when speed of a fluid changes regardless of whether the fluid speeds up or slows down

A

inertial energy loss

39
Q

the tendency of a fluid to resist changes in its velocity

A

inertia

40
Q

inertial energy loss occurs during 3 events

A

pulsatile flow
phasic flow
stenosis

41
Q

velocity increases as the vessel widens/narrows

A

narrows

42
Q

narrowing in the lumen of a vessel

A

stenosis

43
Q

a type of turbulence downstream from the stenosis

A

post-stenotic turbulence

44
Q

describes the relationship between velocity and pressure in a moving fluid

A

Bernoulli’s principle (states that the sum of kinetic energy and pressure energy remains constant)

45
Q

pressure-flow relationship

A

relationship between flow, resistance, and pressure gradient

46
Q

pressure gradient increases when

A

flow increases or when

resistance increases

47
Q

flow increases when

A

pressure gradient increases or

resistance decreases

48
Q

Ohm’s Law

A

voltage = current x resistance

49
Q

fluids

A

pressure
flow
resistance

50
Q

electricity

A

voltage
current
resistance

51
Q

electrical resistance units

A

ohms

52
Q

resistance vessels in the circulatory systems are called

A

arterioles

53
Q

what is the typical resistance of veins

A

low resistance vessels

54
Q

how do veins adapt to increased inflow during periods of exercise?

A

the CSA of the vessel changes to oval and then round to accommodate a large volume increase

55
Q

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

A

hydrostatic pressure

units - mmHg

56
Q

clinical significance of hydrostatic pressure

A

when taking a patients blood pressure

57
Q

supine

A

laying flat on back

58
Q

during supine position, the hydrostatic pressure is

A

zero everywhere

Ultrasound Physics (24 decks)

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