Doppler

Question 1

Flow

Answer 1

aka volume flow rate. Indicates the volume of blood moving during a particular time.

Question 2

Velocity

Answer 2

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

Question 3

Pulsatile flow

Answer 3

occurs when blood moves with a variable velocity. Blood accelerates and decelerates as a result of cardiac contraction; therefore, pulsatile flow commonly appears in the arterial circulation.

Question 4

Phasic Flow

Answer 4

Also occurs when blood moves with a variable velocity. Blood accelerates and decelerates as a result of respiration; therefore, phasic flow often appears in venous circulation.

Question 5

Steady Flow

Answer 5

Occurs when a fluid moves at a constant speed or velocity. Water flowing through a garden hose is an example of steady flow. Steady flow is present in the venous circulation when individuals stop breathing for a brief moment.

Question 6

Laminar Flow

Answer 6

is when the flow streamlines are aligned and parallel. The word lamina means layer. Laminar flow is characterized by layers of blood that travel at individual speeds. Laminar flow patterns are commonly found in normal physiologic states.

Question 7

Plug Flow

Answer 7

occurs when all of the layers and blood cells travel at the same velocity

Question 8

Parabolic Flow

Answer 8

has a bullet-shaped profile. Velocity is highest in the center of the lumen, and gradually decreases to its minimum at the vessel wall

Question 9

Turbulent Flow

Answer 9

characterized by chaotic flow patterns in many different directions and at many speeds. The streamlines are often obliterated.

Question 10

Buit

Answer 10

Sound associated with turbulence

Question 11

Thrill

Answer 11

Tissue vibration associated with turbulence.

Question 12

Reynolds number

Answer 12

predicts whether flow is laminar or turbulent. The Reynolds number of turbulent flow is greater than 2,000

Question 13

Energy gradiant

Answer 13

Blood moves from higher energy to lower energy

Question 14

Forms of energy- Kinetic pressure gravitational

Answer 14

Kinetic is associated with a moving object
Pressure is a form of stored of potential energy. It is a major form of energy for circulating blood and creates flow by overcoming resistance
Gravitational is a form of stored or potential energy. is associated with any elevated object.

Question 15

Energy losses in circulation - Viscous, Frictional, Inertial

Answer 15

Viscous- describes the thickness of fluid.
Frictional- frictional losses occur when flow energy is converted to heat as one object rubs against another.
Inertial- relates to the tendency of a fluid to resist changes in its velocity

Question 16

Stenosis

Answer 16

a narrowing in the lumen of a vessel

Question 17

Effects of stenosis

Answer 17

changes in direction as blood flows into and out of the narrow portion of the vessel
increased velocity within the stenosis
Turbulence downstream from stenosis
pressure gradient across the stenosis
loss of pulsatility

Question 18

Bernoulli’s Principle

Answer 18

describes the relationship between velocity and pressure in a moving fluid. It is derived from the principle of conversation of energy. This principle states that with a steady flow, the sum of all forms of energy is the same everywhere.

Question 19

Pressure Flow Relationships

Answer 19

pressure gradient=flow x resistance
pressure gradient increases when either flow increases or resistance increases
Flow increases when pressure gradient increases or resistance decreases.

Question 20

Ohm’s Law

Answer 20

voltage = current x resistance

Question 21

Hydrostatic pressure

Answer 21

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

Question 22

Breathing & Venous flow- Expiration & Inspiration

Answer 22

Breathing effects venous flow because venous system is low pressure and muscles responsible for respiration alter pressures in the thorax and abdomen.
Inspiration- diaphragm moves down, thoracic pressure decreases, abdominal pressure increases, venous return to the heart increases, venous flow in legs decrease
Expiration- diaphragm moves up, thoracic pressure increases, abdominal pressure decreases, venous return to the heart decreases, venous flow in legs incease.