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Physics II for Ultrasound > 18 Hemodynamics Practice > Flashcards

18 Hemodynamics Practice Flashcards

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1
Q

What is the equation that describes the relationship between pressure gradient, resistance, and flow in a vessel?

A

Pressure gradient= flow x resistance

(Flow and pressure gradient have a direct relationship. One goes up, the other goes up.
Resistance and pressure gradient have an inverse relationship. )

This is a Variation on OHM’s law (whiche typically applies to electrical systems)

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2
Q

What is ohms law

A

A law in electrics where voltage= current•resistance

Voltage and current have a direct relationship.
Voltage and resistance have an inverse relationship.

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3
Q

Blunt flow is the other term for plug flow-

true or false

A

True

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4
Q

The flow of blood is dependent on two factors…

A

Resistance

Pressure gradient along a vessel

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5
Q

Resistance to bloodflow is dependent on three factors…

A

The viscosity of the blood
Radius of the lumen
length of the vessel

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6
Q

The maximum velocity is right after the stenotic area.

True or false?

A

False the maximum velocity is achieved at the most severe narrowing of a stenosis

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7
Q

Kinetic energy, (which is the energy associated with moving objects and determined by its mass and speed) is the maximum at the stenotic area. True or false?

A

True it is at max velocity- therefor the Kinetic energy is also at the maximum

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8
Q

Pulsatile flow is seen in _____and it’s the result of______.

A

Arteries
Cardiac contraction
(blood has various velocities during the cycle)

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9
Q

_____ flow is seen in _____and it’s the result of______.

A

Phasic
Veins
Respiration

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10
Q

PSV stands for

A

Peak systolic volume

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11
Q

EDV stands for

A

End diastolic volume

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12
Q

As more vessels dilate in the peripheral circulation, resistance is _____and cardiac output becomes______

A

Decreased

Greater

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13
Q

For a parabolic velocity profile, the average velocity through the lumen is equal to half the maximum velocity. True or false

A

True because it is bullet shaped.

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14
Q

The X axis on a spectral graph represents

A

Time

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15
Q

The Y axis on a spectral graph represents

A

Velocity

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16
Q

What’s the term that used to describe the relationship between velocity and pressure in the blood vessels?

A

Velocity profile

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17
Q

Plug flow is seen at the entry of arteries true or false

A

False plug flow is mainly only large vessels like the thoracic Aorta.

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18
Q

Velocity decreases in the area post stenosis true or false

A

True

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19
Q

The total energy at a specific location within the circulation is the sum of_____,_____,and ______energies.

A

Kinetic energy
Pressure energy
Gravitational energy

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20
Q

In plug flow, all layers of blood have the same velocity. True or false

A

True

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21
Q

Laminar flow is seen in long, straight arteries. True or false?

A

True

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22
Q

Disturbed flow is only seen in pathological conditions of the vessels. True or false

A

False disturbed flow is seen in curbing, branching, diverging vessels and by projections into the lumen.

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23
Q

The term that is used to describe turbulent flow currents are _____and______.

A

Eddie currents

A vortex

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24
Q

Turbulent flow is seen right after the stenotic area. True or false?

A

False. flow reversal is seen immediately after stenosis followed THEN by turbulent flow

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25
Q

The sound is called ____or ______which can be heard by the stethoscope at the site of stenosis

A

Murmur

Bruit

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26
Q

The pressure energy is the maximum right after the stenotic area true or false?

A

True. Kinetic Energy drops after the stenotic area and pressure energy goes up.

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27
Q

According to the law of conservation of energy, the sum of _____energy and _______stays the same.

A

Kinetic energy

Pressure energy

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28
Q

blood energy loss is due to three factors…

A

Viscous energy loss
Frictional energy loss
Inertia energy loss

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29
Q

When the Kinetic energy increases at an area in the vessel, the pressure energy increases as well, true or false?

A

False according to the law of the conservation of energy- as Kinetic energy increases, pressure energy decreases.

30
Q

If the Reynolds number is less than 1500, this reflects laminar flow. True or false

A

True laminar flow is represented by a number less than 1500. Turbulent flow is a Reynolds number of greater than 2000

31
Q

An area of reversal of flow is seen right after the stenotic area and before the turbulent flow is seen true or false

A

True

32
Q

What are the units that are used to measure:
A:blood flow
B:velocity
C:blood pressure

A

Flow- ml/s
Velocity-cm/s
Blood pressure- mm/hg

33
Q

Intravascular pressure is produced by three different pressures…

Which is the least important?

A

Pressure from heart contraction
Static filling pressure
Hydrostatic pressure.

Static filling pressure

34
Q

Blood flow in the vessels because of its energy gradient not because of its pressure gradient, true or false?

A

True. Blood flow is the result of its energy gradient.

35
Q

What does inertia mean?

A

An objects’ tendency to resist changes in velocity

36
Q

The tissue vibration at the point of stenosis is called a

A

Thrill

37
Q

The primary regulatory control on cardiac output is

A

Peripheral resistance

38
Q

In polycythemia, resistance to bloodflow is increased true or false

A

True- due to increased blood cells and increased blood viscosity anemia with its decreased blood cells resistance is decreased

39
Q

For a similar increase in pressure, a vein can contain 6 to 10 times the volume of blood as an artery of a comparable size true or false

A

True

40
Q

What is the equation that describes the relationship between the true pressure hydrostatic pressure and measured pressure of the blood?

A

Measured pressure =

True pressure + hydrostatic pressure

41
Q

In a supine patient, the hydrostatic pressure at the knee is 30 mm/HG true or false

A

False supine patient have a hydrostatic pressure of zero everywhere

42
Q

In a standing patient, the hydrostatic pressure at the heart level is 0MM/HG true or false

A

True the heart is the reference point

43
Q

Flow and resistance are directly related true or false?

A

False flow and resistance have an inverse relationship

44
Q

What is the true pressure at the knee level on someone who is standing and they are measured pressure was 210 MM/HG?

A

135 MM/HG is the true pressure. Knee is +75

45
Q

Bernoulli’s principle describes the relationship between _____and_____

A

Velocity

Pressure in blood vessels

46
Q

What is the hydrostatic pressure at the hip level on a supine patient if the true pressure is 15 MM/HG?

A

The hydrostatic pressure at the hip level on a supine patient is zero…because they are supine

47
Q

When the diameter of a vessel increases, the flow decreases true or false

A

False flow increases when resistance decreases like when a diameter on a vessel widens

48
Q

Exercise causes _____of lower extremity arteries which_____ the resistance to flow.

A

Dilation

Decreases

49
Q

When the viscosity of blood decreases the resistance increases. true or false?

A

False when the viscosity decreases, resistance decreases

50
Q

During inspiration, the diaphragm ascends increasing pressure in the thoracic cavity true or false?

A

False the diaphragm descends during inspiration

51
Q

______ flow is the localized slow rotation of concentric blood layers

A

Eddie

52
Q

Flow and pressure gradient are directly related true or false?

A

True

53
Q

During expiration Venus flow in the lower extremities is increased true or false

A

True.

54
Q

During inspiration, Venus flow in the upper extremities is increased true or false

A

True

55
Q

What is the measured blood pressure at the ankle on a standing patient with true pressure which is 130 MM/HG

A

The measured pressure is 230 MM/HG

The ankle is +100

56
Q

Eddie flow occurs at arterial by furcation, within vessels undergoing rapid expansion of luminal diameter, and distal to an obstruction. True or false

A

True

57
Q

Bernoulli’s principle is derived from…

A

The law of conservation of energy which states that energy is never lost- it simply changes form

58
Q

The change in velocity within the heart cycle are characterized by the _____index.

A

Pulsatility index

59
Q

What is the mathematical relationship for the pulsatility index?

A

PI=PSV-EDV/mean volume

60
Q

Blood loses its energy only when it accelerates true or false?

A

False energy is lost both with acceleration and deceleration

61
Q

Turbulent flow converts flow energy into other forms such as _____and______.

A

Sound

Vibration

62
Q

_______ Number indicate whether the flow is laminar or turbulent

A

The Reynolds number

63
Q

What is the Reynolds equation?

A

Renolds #=p•d•v/n

P is density of fluid
D is diameter of vessel
V is velocity of the blood
N is viscosity of the fluid

64
Q

A zone of stagnant flow, called________,divides the circular notion of Eddie flow from the central region of high velocity flow

A

Flow separation

65
Q

________ slow is the term used to describe laminar flow

A

Parabolic

66
Q

Where do we see phasic flow?

A

Phasic flow is found in veins

67
Q

Where do we see pulsatile flow?

A

Pulsatile flow is found in arteries

68
Q

Velocity changes in the visceral arteries between ______and_____.

A

Systole

Diastole

69
Q

Where do we see steady flow?

A

Steady flow is seen in veins, upon cessation of breathing.

70
Q

The velocity profile is highly variable depending on anatomical location, true or false?

A

True

71
Q

As pressure gradient decreases, flow increases true or false

A

False pressure gradient and flow have a direct relationship as one increases the other increases

Physics II for Ultrasound (2 decks)

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