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Intro > Ch. 18 Hemodynamics > Flashcards

Ch. 18 Hemodynamics Flashcards

1
Q

__________________________________ is the study of blood moving through the circulatory system.

A

Hemodynamics is the study of blood moving through the circulatory system

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2
Q

______________, also called volume flow rate, indicates the volume of blood moving during a particular time.

A

Flow, also called flow rate, indicates the volume of blood moving during a particular time.

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3
Q

Units for flow:

A

volume/ time

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4
Q

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

A

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

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5
Q

Units for velocity:

A

distance/ time

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6
Q

what are the 3 basic forms of bloodflow?

A
  1. pulsatile
  2. phasic
  3. steady
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7
Q

________________________ flow is when blood accelerates and decelerates as a result of cardiac contraction; therefore this flow appears in the arterial circulation.

A

Pulsatile flow is when blood accelerates and decelerates as a result of cardiac contraction; therefore this flow appears in the arterial circulation

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8
Q

________________________ flow also occurs when blood accelerates and decelerates as a result of respiration; appears in the venous circulation.

A

Phasic flow also occurs when blood accelerates and decelerates as a result of respiration; appears in the venous circulation

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9
Q

______________________ flow occurs when a fluid moves at a constant speed or velocity.

A

Steady flow occurs when a fluid moves at a constant speed or velocity.

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10
Q

____________________ flow is when the flow streamlines are aligned and parallel (normal physiologic states)

A

Laminar flow is when the flow streamlines are aligned and parallel (normal physiologic states)

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11
Q

What are the 2 forms of Laminar flow?

A
  1. Plug Flow
  2. Parabolic Flow
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12
Q

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

A

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

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13
Q

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

A

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

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14
Q

The _____________________________ predicts whether flow is laminar or turbulent.

A

The Reynolds number predicts whether flow is laminar or turbulent

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15
Q

The Reynolds number for laminar flow is less than _________________

A

The Reynolds number for laminar flow is less than 1,500

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16
Q

____________________ flow is characterized by chaotic flow patterns in many different directions and at many speeds.

A

Turbulent flow is characterized by chaotic flow patterns in many different directions and at many speeds

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17
Q

Turbulence is often associated with cardiovascular ______________________ and elevated blood ______________________

A

Turbulence is often associated with cardiovascular pathology and elevated blood velocities

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18
Q

sound associated with turbulence is called a _________________ or _____________________

A

sound associated with turbulence is called a murmur or bruit

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19
Q

Tissue vibration associated with turbulence is called a _____________

A

Tissue vibration associated with turbulence is called a thrill

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20
Q

The Reynolds number for turbulent flow is greater than ________________

A

The Reynolds number for turbulent flow is greater than 2,000

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21
Q

When blood moves from regions of higher energy to lower energy this is called __________________________ (pressure difference)

A

When blood moves from regions of higher energy to lower energy this is called energy gradient (pressure difference)

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22
Q

What are the 3 energy forms associated with blood?

A
  1. kinetic energy
  2. pressure or potential energy
  3. gravitational energy
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23
Q

_______________________ energy is the ability of blood to do work as a result of its velocity. Associated with a moving object

A

Kinetic energy is the ability of blood to do work as a result of its velocity

24
Q

Kinetic energy is determined by two factors:
an objects _______________ and the ______________ at which it moves

A

Kinectic energy is determined by

an objects mass and the speed at which it moves

25
Q

____________________ or ________________________ energy is pressure force energy, it is the main form of energy found in flowing blood

A

Pressure Energy or Potential Energy is pressure force energy, it is the main form of energy found in flowing blood_____

26
Q

How does pressure create blood flow?

A

by overcoming resistance

27
Q

_________________________ energy is the ability to do work as a result of gravity, it is a form of stored or potential energy.

A

Gravitational Energy is the ability to do work as a result of gravity, it is a form of stored or potential energy

28
Q

As blood flows through the circulation, energy is lost in 3 ways:

A
  1. viscous loss
  2. friction loss
  3. inertial loss
29
Q

_______________________describes the thickness of a fluid; so __________________ energy loss is associated with blood overcoming its internal stickiness.

A

Viscosity describes the thickness of a fluid; so viscous energy loss is associated with blood overcoming its internal stickiness

30
Q

Viscous energy loss in blood is determined by ___________________________

A

Viscous energy loss in blood is determined by hematocrit

31
Q

What is the normal average hematocrit?

A

45%

32
Q

_________________________ energy loss occurs when flow energy is converted to heat as one object rubs against another.

A

Frictional energy loss occurs when flow energy is converted to heat as one object rubs against another

33
Q

____________________ energy loss is the tendency of blood to resist changes in velocity

A

Inertial energy loss is the tendency of blood to resist changes in velocity

34
Q

When does Inertial energy loss occur?

A
  1. pulsatile flow
  2. phasic flow
  3. velocity changes at a stenosis
35
Q

Velocity is ___________________ when the vessel narrows, and ___________________ when the vessel widens

A

Velocity is greater when the vessel narrows, and weaker when the vessel widens

36
Q

______________________is the narrowing in the lumen of a vessel

A

stenosis is the narrowing in the lumen of a vessel

37
Q

What are the effects of a stenosis?

A

change in flow direction
increased velocity as vessel narrows
tubulence downstream form the stenosis
pressure gradient across the stenosis
loss of pulsatility

38
Q

__________________________________ states that generally as a vessel narrows flow velocity increases and pressure simultaneously decreases. Pressure energy is converted into kinetic energy.

A

Bernoulli’s Principle states that generally as a vessel narrows flow velocity increases and pressure simultaneously decreases. Pressure energy is converted into kinetic energy.

39
Q

pressure gradient =

A

flow x resistance

40
Q

voltage =

A

current x resistance

41
Q

How does Ohms law relate to pressure gradient?

A

pressure gradient is analogous to voltage; flow is analogous to current; resistance is the same

42
Q

Electrical resistance is reported in units of:

A

Ohms

43
Q

What are the circulatory system’s resistance vessels?

A

arterioles

44
Q

What are the main characteristics of veins?

A

Thin-walled and collapsible, low resistance vessels

45
Q

Describe veins during normal function

A

low pressure, partially filled with blood, partially expanded (flattened hourglass shape)

46
Q

Venous inflow

A

hourglass cross sectional shape changes to oval then to round. This allows veins to accommodate a large volume increase with a very small increase in pressure. Once veins empty out they return to their original hourglass shape

47
Q

Why do veins expand during inflow?

A

This allows a high volume of blood with only a small pressure increase; resistance decreases and outflow to heart increases

48
Q

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

A

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

49
Q

When supine, hydrostatic pressure is

A

zero everywhere

50
Q

below the heart the hydrostatic pressure is

A

positive, resulting in a measurement that is too high

51
Q

above the heart, hydrostatic pressure is

A

negative, resulting in a measurement that is too low

52
Q

At the heart, the hydrostatic pressure is

A

zero, the move accurate measurement

53
Q

How does respiration have an effect on the venous system?

A
  1. the venous system is low pressure
  2. muscles responsible for respiration alter pressures in the thorax and abdomen
54
Q

What 2 venous flows does breathing affect?

A
  1. venous flow in the legs
  2. venous return to the heart which compromises venous flow from the head, arms, and IVC to the heart
55
Q

With Inspiration:
Diaphragm moves _______________________ toward the abdomen
Thoracic pressure _________________________
Abdominal pressure ____________________________
Venous return to the heart ________________________
Venous flow in legs ___________________________

A

With Inspiration:

Diaphragm moves downward toward the abdomen

Thoracic pressure decreases

Abdominal pressure increases

Venous return to the heart increases

Venous flow in the legs decreases

56
Q

With Expiration:
Diaphragm moves _________________________ into the thorax
Thoracic pressure _________________________
Abdominal pressure __________________________
Venous return to the heart ______________________
Venous flow in legs ________________________

A

With Expiration:

Diaphragm moves upward into the thorax

Thoracic pressure increases

Abdominal pressure decreases

Venous return to the heart decreases

Venous flow in the legs increases

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