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Vascular > Physiology And Hemodynamics > Flashcards

Physiology And Hemodynamics Flashcards

1
Q

How much blood does the heart pump into the aorta when it makes a blood pressure pulse

A

70 milliliters

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2
Q

How does the aortic valve know to open in order to pump blood

A

When the left ventricle pressure exceeds the pressure in the aorta

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3
Q

______ heart rate delivers an ______ blood pressure.

Increase or decrease

A

INCREASED heart rate delivers an INCREASED blood pressure

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4
Q

Put the following in order from blood circulation out and back into the heart
*aorta *arterioles * venules. *Vena Cava. *left ventricle. *large arteries. *capillaries. *large veins. *right atrium

A

Left ventricle -> aorta -> large arteries -> arterioles -> Capillaries -> Venules -> large veins -> Vena cava -> right atrium

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5
Q

How does the heart help maintain a high pressure gradient between arteries and veins

A

The pumping action of the heart results in a high volume of blood into arteries

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6
Q

What determines the AMOUNT of blood entering the arterial system

A

Cardiac output

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7
Q

What determines the amount of blood leaving the arterial system

A

Arterial pressure and total peripheral resistance

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8
Q

Pressure is greatest at the ____, and decreases as it moves.

A

Greatest at the heart.

*the pressure difference helps maintain blood flow

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9
Q

Movement of any fluid medium between two points requires two things…. What are they

A 
A pathway for fluid to flow
Pressure difference (high pressure to low pressure)
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10
Q

The amount of flow depends on…

2

A 
Energy difference (including losses resulting from fluid movement)
Resistance that tends to oppose movement
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11
Q

What kind of resistance causes high flow rate

A

Low resistance

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12
Q

What kind of resistance causes lower flow rate

A

Higher resistance

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13
Q

The total energy contained in moving fluid is the sum of? (3)

A

Pressure
Kinetic energy
Gravitational energy

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14
Q

Potential/stored energy is which kind

A

Pressure energy

  • released when walls recoil
  • expressed in mmHg
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15
Q

Velocity is which form of energy

A

Kinetic energy

  • small part of circulation
  • expressed in fluid density and velocity (cm/s)
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16
Q

This type of energy is the weight of the column of blood extending from the heart to the level where pressure is measured

A

Gravitational energy (hydrostatic pressure…HP)

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17
Q

If there is a 0mmHg (HP) against arteries and veins at the ankle the patient is in what position

A

Supine (if patient is average size)

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18
Q

If an average sized supine patient decides to stand, what happens to the HP

A

Adds about 100mmHg to ankle vessels

Ankle pressure = circulation pressure plus 100mmHg

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19
Q

The tendency of fluid to resist changes in its velocity

A

Inertia

body at rest tends to stay at rest

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20
Q

As blood moves farther out to the periphery, energy dissipated largely in the form of _______

A

Heat

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21
Q

in the equation for resistance, R(resistance) is directly proportional to which two factors

A

Viscosity and length
*variables in the numerator of the equation

R= 8nL/(pie)r^4

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22
Q

In the equation for resistance, R(resistance) is inversely related to which variable?

A

Radius
*variable in denominator

R= 8nL/(pie)r^4

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23
Q

Of the three variables in the resistance equation, which one effects resistance the MOST
Viscosity, length, or radius

A

Radius

*a change in the radius means there was a change in the vessel diameter

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24
Q

The internal friction of a fluid is measured by?

A

Viscosity

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25
Q

What effect does elevated hematocrit have on the blood viscosity?

A

Will increase the blood viscosity bc it effects the THICKNESS of the fluid

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26
Q

What effect will anemia have on blood viscosity?

A

Decreases blood viscosity

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27
Q

____ viscosity = _____ velocity

A 
Increased viscosity(friction) = DECREASED velocity 
While....
Decreased viscosity = INCREASED velocity
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28
Q

what term described flow that is evenly distributed during systole

A

Laminar

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29
Q

What kind of flow is considered “stable flow”

A

Laminar

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30
Q

______ flow is normally seen at vessel origin and/or initial cardiac upstroke

A

Plug flow

31
Q

______ flow is usually seen downstream once the laminar flow is fully developed

A

Parabolic flow

32
Q

Inertial energy loss occurs when this happens

2

A

Directional change and/or velocity change

33
Q

What type of energy loss occurs at the end of a stenosis?
Viscous energy loss
Internal energy loss

A

Inertial energy loss

34
Q

Poiseuilles equation helps define how much fluid volume moves through the vessel with these three variables

A

Pressure(P), volume flow(Q), resistance(R)

Q = P/R

35
Q

Radius of a vessel is ______ proportional to volume flow

A

Directly

36
Q

The law of conservation of mass explains the relationship between these two things

A

Velocity and area (inversely related)

Q = A x V

37
Q

Benoullis law uses the relationship between what two variables

A

Pressure and velocity (inversely related)

38
Q

Total energy contained in moving fluid is the sum of what?

A

the sum of pressure, kinetic and gravitational energy

39
Q

What’s another name for pressure gradients

A

Flow separation

40
Q

What can cause flow separation (pressure gradient) to occur? (3)

A

Regions with…
Reverse flow, stagnant flow, or little movement

EXAMPLES: valve cusp site, anastomosis of bypass graft

41
Q

Reynolds Number(Re) helps to predict when fluid becomes unstable/disturbed by using these two variables

A

Pressure and flow relationship

42
Q

With Reynolds Number (Re), laminar flow is considered disturbed when it is GREATER than this number

A

Greater than 2000

*unitless number

43
Q

STEADY flow originates from a ____ _____ ____

A

Steady driving PRESSURE

44
Q

This flow changes both driving pressure conditions as well as the response of the system

(Steady VS pulsatile)

A

Pulsatile flow

45
Q

Describe what happens during systole

A

Aortic valve opens causing foward flow throughout the periphery (fluid acceleration)(initial release)

46
Q

Describe what happens during late systole/early diastole

A

Temporary flow reversal due to a phase shift of negative pressure gradient and peripheral resistance

** think of the “biphasic” portion of a waveform

47
Q

The dicrotic notch is related to the closing of ____ and the influence of _____ ______

A

Closing of aortic valve and influence of peripheral resistance

  • when aortic valve closes diastole begins *
48
Q

Describe late diastole

A

Flow is foward again

49
Q

T/F

Diastole reflects where the blood is going to

A

TRUE

50
Q

The ICA, vertebral, renal, celiac, splenic, and hepatic arteries are all examples of what resistance

A

LOW resistance

  • organs you can’t live without *
51
Q

The ECA, subclavian, aorta, iliac, fasting SMA, and arteries in extremities are all what type of resistance

A

High resistance

52
Q

The reversal component in a high resistance waveform may disappear distal to ______ b/c of a decreased peripheral resistance

A

Stenosis

*this is secondary to ischemia

53
Q

What is the appearance of a waveform that is distal to a significant stenosis

A

Can show…
low resistance
More rounded
Weaker strength

54
Q

What kind of flow should we expect proximal to a significant stenosis

A

May become…
monophasic
Higher resistance

55
Q

VasoCONSTRICTION causes medium/small arteries to have a ______ in pulsitility, and a ______ in minute arteries

A 
Medium/small = increase
Minute = decrease
56
Q

VasoDILATATION causes medium/small arteries to have a ______ in pulsitility, and a ______ in minute arteries

A 
Medium/small = decrease (lower resistance)
Minute = increase
57
Q

At rest, can blood flow seem normal even if there is a stenosis or complete occlusion of a main artery, why?

A

Yes, because of collateral networks

58
Q

With arterial obstruction, the collateral channels may have an altered flow. What are the changes that occur in the collateral channel flow

A

Elevated velocity
Increased flow volume
Pulsatility changes

59
Q

What are some causes of exercise

A

Peripheral vasodilation which lowers distal peripheral resistance, enhancing blood flow

60
Q

Exercise helps regulate this due to the vasoconstriction and vasodilatation of the vessels in the skeletal muscles

A

Regulates body temperature bc of the sympathetic nervous system response

61
Q

_____ is a key vasodilator of the resistance vessels in the skeletal system

A

Exercise

62
Q

The ability of most vascular beds to maintain constant level of blood flow over a wide range of perfusion pressures is?

A

autoregulation

63
Q

In resistant vessels, constriction causes BP to ___, and dilation causes BP to _____

A 
Constriction = rise
Dilatation = fall
64
Q

A vigorous exercise causes vasodilatation, making the waveform look…

A

Low resistant with monophasic flow

65
Q

Vasoconstriction and pulsatile waveform is seen with a warm or a cold extremity?

A

Cold

  • warm extremity means vasodilatation and a continuous waveform
66
Q

T/F

distal effects of obstructive disease may only be detectable following stress (exercise)

A

True

67
Q

A hemodynamically significant stenosis causes a notable reduction in what two things

A

Volume flow and pressure

68
Q

A cross sectional area reduction of 75% = a diameter reduction of what percent

A

50%

69
Q

Effects of flow abnormality produced by a stenosis depends on factors such as…

A

Length/diameter/shape of narrowing
Multiple obstructions in the Same vessel
Obstructions in different vessels that are parallel
Pressure gradient

70
Q

A dampened waveform is usually _____ to a stenosis

A

Proximal

71
Q

Entrance into a stenosis produces an increased Doppler shift frequencies (DSF), which makes the waveform look like what

A 
Spectral broadening ( wide range of velocities)
Elevated velocities
72
Q

Flow disturbance occurs with what kind of velocities

A

High velocities and eddy currents

73
Q

Post-stenosis causes what kind of flow

A

Turbulence

(Flow reversal, flow separation, vortices/eddy currents

Vascular (15 decks)

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