Ch 18, 19, and 20 Key Terms Flashcards Preview

DMSO Physics 2 > Ch 18, 19, and 20 Key Terms > Flashcards

Flashcards in Ch 18, 19, and 20 Key Terms Deck (33):
1

Hemodynamics

study of blood moving through the circulatory system

2

Flow

indicates the volume of blood moving during a particular time

3

Velocity

indicates the speed or swiftness of a fluid moving from one location to another

4

Laminar vs. turbulent Laminar

when the flow streamlines are aligned and parallel

5

Laminar vs. turbulent Turbulent

chaotic flow patterns in many different directions and at many speeds

6

Reynolds number

predicts whether flow is laminar or turbulent, unit less number

7

Forms of energy

kinetic, pressure, and gravitational

8

Energy losses in circulation

viscous loss, frictional loss, and inertial loss

9

Stenosis

narrowing in the lumen of a vessel

10

Bernoulli’s principle:

relationship between velocity and pressure in a moving fluid

11

Ohm’s law

pressure gradient = flow x resistance

12

Venous hemodynamics

normal function = low pressure, partially filled with blood and only partial expanded

13

Hydrostatic pressure

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

14

Doppler frequency

the change in frequency

15

Frequency shift

created when transmitted sound waves strike moving red blood cells

16

Speed vs. velocity Speed

purely magnitude, indicates the distance that red blood cells moves in 1 second

17

Speed vs. velocity Velocity

defined by a magnitude and a direction, length of arrow indicates magnitude and angle indicates direction

18

Doppler equation

Doppler shift = 2 x velocity x transducer frequency x cos / propagation speed

19

Sound beam direction vs. flow direction

Doppler shift represents 100% of true velocity when blood flow is parallel to sound beam. When there is an angle, Doppler measures less than the true velocity

20

Bidirectional Doppler

distinguish the flow to and away from transducer, positive toward, negative away

21

Continuous wave Doppler

two crystals, one constantly transmits and one constantly receives

22

Pulsed wave Doppler

one pzt is necessary, alternated between sending and receiving sound pulses

23

Aliasing

22. Aliasing: false: identity, high velocity in one direction are incorrect, flow above baseline, bottom part of spectrum

24

Nyquist limit

high Doppler frequency or velocity that can be measuring without the appearance of aliasing, top of spectrum

25

Gray shades of a spectrum

related to amplitude of reflected sound or number of blood cells creating the reflection

26

Color flow Doppler

measure mean velocity, is pulsed technique, range resolution, and subject to aliasing

27

Color maps

convert measured velocities into colors that appear on the image

28

Doppler packets

multiple ultrasounds pulses are used to accurately determine blood velocities

29

Power Doppler

only identifies the presence of a Doppler shift, doesn’t evaluate speed or direction

30

Spectral analysis

tools that breaks the complex signal into tis basic “building blocks” and identifies the individual velocities that make up reflected Doppler signal

31

FFT

digital technique, is used to process both pulsed and continuous wave Doppler signals

32

Autocorrelation

digital technique used to analyze color flow Doppler

33

Wall filter

removes the color form slowly moving reflectors such as blood cells and vibrating tissue