Which of the following is the driving force of blood flow?

1. If the received and transmitted frequencies are identical, which of the following will occur?

 

a. no Doppler shift

b. positive Doppler shift

c. negative Doppler shift

d. proportional Doppler shift

2. A major advantage of continuous wave Doppler is the:

a. ease of use

b. small probe size

c. ability to measure high velocities

d. interrogation of multiple vessels simultaneously

3. The Doppler equation determines the:

a. volume flow rate

b. Reynolds number

c. cosine of the Doppler angle

d. change in the transmitted and received fre­quencies

4. Which of the following is the most consistent predictor of turbulent flow?

a. Doppler shift

b. resistive index

c. pressure gradient

d. Reynolds number

5. Which of the following is required for blood flow to occur?

a. Doppler shift

b. kinetic energy

c. pressure gradient

d. high cardiac output

6. The speed at which blood travels through a vessel is more likely dependent on which of the following?

a. volume flow rate

b. size of the capillaries

c. left-ventricular output

d. resistance of the venules

7. In which of the following positions is venous pressure the lowest?

a. erect

b. supine

c. decubitus

d. semierect

8. The greatest portion of circulating blood is located in the:

a. brain

b. heart

c. venous system

d. arterial system

9. What type of blood flow occurs if the average flow velocity is equal to one half the maximum flow speed in the center?

a. plug flow

b. laminar flow

c. pulsatile flow

d. parabolic flow

10. Normal respiratory variations in venous blood flow are termed:

a. phasic

b. pulsatile

c. spontaneous

d. bidirectional

11. Which of the following is a disadvantage of duplex imaging?

a. decrease in imaging frame rate

b. combines imaging and Doppler information

c. allows measurement only of mean velocities

d. inability to use high operating frequencies

12. Noise within the Doppler signal is known as:

a. flash

b. clutter

c. aliasing

d. acoustic speckle

13. Which of the following is the driving force of blood flow?

a. velocity

b. pressure

c. resistance

d. volume flow rate

14. Observed frequency changes in moving structures

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