Physics Chapters 5 and 6 Flashcards
A doppler shift at 60 degrees is _________ what it would be at 0 degrees
One half
A change in doppler frequency caused by motion of a source or reflector defines
Doppler effect
A nonsteady flow with acceleration and deceleration over the cardiac cycle is called________
pulsatile flow
Continuous wave doppler shifts are detected within the ____________
Overlapped region of the transmitting and receiving beams
Determining the direction of the doppler shift voltages is accomplished by the ___________
Phase quadrateure detector
Doppler measurements are not reliable at doppler angles greater than
60
Doppler shift does not depend on the
flow direction
Echoes arrive from the sample volume depth at a rate equal to
the pulse repetition frequency
For a given flow, the greater the doppler angle, the_________ the doppler shift
less
Gases, nutrients and waste products are exchanged through the walls of__________
capillaries
If pressure differences in a straight vessel increase, the flow rate____
increases
Motion toward the transducer demonstrates
a positive doppler shift
Poise is a unit given for________
viscosity
Poiseuille’s equation states that, if the flow rate increases the
tube diameter has increased
Resistance to flow offered by a fluid in motion describes
viscosity
Sound reflects totally at the wall-blood boundary once the doppler angle is less than _________ degrees
30
Spectral broadening may be produced by
beam spreading in arrays
The doppler equation relates the doppler shift to the
flow speed and frequency
The amount of blood passing a point per unit of time defines
volumetric flow rate
The angle of incidence is not important with which doppler display?
power
The decreased pressure is regions of high flow speed is called
Bernoulli effect
The difference between the emitted frequency and the echo frequency returning from a moving scatter is called
Doppler shift
The fast fourier transform derives the Doppler__________
spectrum
The horizontal presentation in the spectral display represents
time
The resistance of the__________ accounts for about one half of the total resistance in the systemic circulation
arterioles
The volumetric flow rate is equal to __________
average flow rate across the vessel multiplied by the cross sectional area of the vessel
The width of the sample volume is determined by the
beam width and sample volume depth
Turbulent flow is a form of ___________ flow
nonlaminar
Variance color maps demonstrate a change of hues from
left to right
Vertical thickening of spectral tracing is called
spectral broadening
What advantage does spectral analysis have when compared to other doppler techniques?
Spectral analysis displays peak systolic velocities
What is required for flow to occur
pressure difference`
What is the driving force behind blood flow
Pressure
What type of blood flow demonstrates layers of fluid sliding over each other?
Laminar
Which flow type demonstrates a flow velocity that is essentially constant across the vessel
plug
Which matter is considered fluid
gases and liquids
Which of the following doppler displays cannot determine flow direction?
Power
Which of the following doppler techniques must be time shared?
Duplex imaging
Which of the following is an advantage of pulsed doppler
depth of sample volume can be accurately selected
Which of the following pulsed doppler techniques is most likely to demonstrate slow flow velocities in deep vessels?
power doppler