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Spring: Physics > Study guide test 3 > Flashcards

Study guide test 3 Flashcards

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1
Q

What is the movement of fluid from one location to another?

A

velocity

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2
Q

Fluid moving with a variable velocity, that accelerates and decelerates; what is it?

A

pulsatile flow

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3
Q

What is fluid moving from one location to another that accelerates and decelerates from respiration called?

A

phasic flow

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4
Q

What type of flow pattern will be seen with normal physiological states?

A

laminar flow

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5
Q

Chaotic flow with many directions and speeds, whay type of flow is this?

A

turbulent flow

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6
Q

Frictional loss occurs when one object rubs against another. Blood sliding across vessel walls would be considered what?

A

frictional loss

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7
Q

Know the Reynolds numbers

A

< 1500= laminar

1500-2000= ????

>2000= turbulent

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8
Q

What are the effects of stenosis?

A

change in flow direction

increased velocity as vessel narrows

turbulence downstream from the stenosis

pressure gradient across the stenosis

loss of pulsatility

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9
Q

What is hydrostatic pressure?

A

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

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10
Q

Hydrostatic pressure in a supine patient with a blod pressure of 140mmHg

A

all measurement sites= 0mmHg

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11
Q

Hydrostatic pressure while standing upright in a patient with a blood pressure of 140mmHg:

A

ankle: level-far below heart level, hydrostatic pressure-100mmHg, measured pressure-240mmHg
knee: level-somewhat below heart, hydrostatic pressure-75mmHg, measured pressure-215mmHg
waist: level-slightly below heart, hydrostatic pressure-50mmHg, measured pressure-190mmHg

mid chest: level-heart level, hydrostatic pressure-0mmHg, measured pressure-140mmHg

top of head: level-above heart, hydrostatic presure–30mmHg, measured pressure-110mmHg

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12
Q

What does the Doppler shift provide information about?

A

measures the velocity of blood in the circulation

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13
Q

What is a positive Doppler shift?

A

blood moves towards transducer (arteries)

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14
Q

What is a negative Doppler shift?

A

blood moves away from transducer (veins)

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15
Q

What is the typical range of a Doppler shift?

A

20Hz to 20,000Hz (range of audible sound)

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16
Q

What is the phenomenon where high velocities appear as negative?

A

aliasing

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17
Q

When the sample volume is deep, the PRF is what? Nyquist limit?

A

low

18
Q

What are the 5 ways to eliminate aliasing?

A

adjust the scale to its maximum-increases Nyquist limit

select a new ultrasonic view with a shallower sample volume-increases Nyquist limit

select a lower frequency transducer-decreases Doppler shift

use baseline shift-aliasing remains but display more appealing

use continuous wave Doppler-never aliases, but range ambiguity

19
Q

Know about large and small sample volumes. Which one will fill in on Doppler?

A

large spectral broading

20
Q

What do the X and Y axis stand for on the Doppler spectrum?

A

X=time

Y=shift or velocity

21
Q

What 2 things are related to Doppler spectrum?

A

amplitude of the reflected signal

number of blood cells creating the reflection

22
Q

When we look at our Doppler Spectrums and we see our wave form, if you have a higher waveform, is a higher freq or lower freq being used?

A

higher frequency

23
Q

What is Doppler shift inversely related to?

A

propagation speed

24
Q

What is the basic Doppler system that simply identifies blood flow by the pressence of the frequency shift?

A
25
Q

What is the Doppler effect?

A

frequency shift

26
Q

What is the difference betwen speed and velocity?

A

speed measures distance

velocity measures magnitude and direction

27
Q

Know about angles with Doppler:

A

when the angle between the direction of motion and sound is 0º or 180º, flow is parallel to the sound beam

the measured and true velocities are equal: Cosine 0º=1 (flow toward transducer), Cosine 180º=-1 (flow away from transducer)

Cosine 90º=0 (perpindicular/normal incidence can not measure Doppler shifts and velocities

28
Q

What’s a primary advantage for pulsed wave Doppler?

A

range resolution (being able to select the exact location where velocities are measured)

29
Q

What’s the primary advantage to continuous wave Doppler?

A

ability to accurately measure very high velocities

30
Q

What kind of processing does bidirectional Doppler use?

A

phase quadrature

31
Q

Fast Fourier Transform (FFT) is used in what type of process?

A

used to process both pulsed and continuous wave Doppler signals

32
Q

What type of velocities does color flow measure?

A

negative and positive shifts

slower and faster velocities

laminar and turbulent flow

33
Q

What is autocorrelation?

A

a digital technique used to analyze color flow Doppler

34
Q

What are the personal limitations to color flow imaging?

A

more time needed to aquire data

reduced frame rate

decreased temporal resolution

35
Q

What is the area of interrogation in a Pulsed Doppler jam called?

A

sample volume

36
Q

What are the advantages and disadvantages of large Doppler packets?

A

Advantages:

more accurate velocity measurement, increased sensitivity to low flow

Disadvantages:

more time needed to aquire data, reduced frame rate, decreased temporal resolution

37
Q

How do you measure low flow rates?

A
38
Q

Know about inspiration:

A

diaphragm moves upward toward abdomen

thoracic pressure decreases

abdominal pressure increases

venous return to the heart increases

venous flow in legs decreases

39
Q

Know about expiration:

A

diaphragm moves upward into thorax

thoracic pressure increases

abdominal pressure decreases

venous return to the heart decreases

venous flow in legs increases

40
Q

When venous pressure is low, what is the volume of pressure in the veins?

A

low

41
Q

What happens to the shape of veins when the venous pressure increases?

A

becomes more circular

Spring: Physics (10 decks)

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