Chapter 2- Arterial Hemodynamics

Question 1

Where in the body is pressure the greatest?

Answer 1

At the heart ;

it decreases as it moves further away from the heart

Question 2

movement of any fluid medium between two points requires what two things?

Answer 2

1) a PATHWAY along the fluid can flow

2) Difference in energy levels (pressure/energy differential )

Question 3

The amount of flow moving through the circulatory system depends on

Important

Answer 3

energy difference and resistance

Question 4

Blood leaves the heart with a mean pressure of

Answer 4

85-95 mmHG

Think about how hot that is if that was the weather outside. It would make my heart beat fast.

Question 5

Arterioles are also known as “_____” vessels

Answer 5

Resistance

Question 6

The pressure in an arteriole drops down to

Answer 6

25-30 mmHg

Question 7

Once the blood comes back to the heart in the right atrium the pressure measures

Answer 7

0 mmhg

Question 8

REMEMER:

Blood moves from an area of (high or low?) pressure to areas of (high or low) pressure?

Remember heart is has the highest amount of pressure :)

Answer 8

High to low pressure

Heart is always the highest

Question 9

What causes blood to move?

Answer 9

Energy

Question 10

What are the three types of energy?

Answer 10

Potential Energy, Kinenetic energy and gravitational energy

Also known as pressure, motion, and hydrostatic energy

Question 11

In this analogy, identify which energy sources are used in which part.

The water tower

Water coming out of a faucet

Turning on the water faucet

Answer 11

The water tower is the potential energy. Its being stored (potential energy). When you turn on the water in a faucet, that is the hydrostatic pressure being released. The water coming out of the faucet is the motion/kinetic energy :)

Question 12

The ejection of blood from the heart into the arteries distends the elastic artery wall and this becomes ________. What kind of energy is this describing?

Answer 12

Stored energy/potential energy

Question 13

During potential energy, how is the energy released?

Answer 13

when the walls recoil.

Question 14

What is kinetic energy?

Answer 14

it comes from the movement of blood as it ejects from the heart.

Question 15

The weight of the column of blood from the heart to the level where the pressure is measured. THIS IS VERY IMPORTANT IN VENOUS CIRCULATION. what kind of energy is this?

Answer 15

Hydrostatic / Gravitational energy

Question 16

When a patient is laying down The arteries and veins are about the same level as the heart. What is the hydrostatic pressure at that point?

Answer 16

0 mmhg

everything is equal. 0 difference

Question 17

When the patient stands up the hydrostatic pressure increases at the ankles, making the pressure ____ mmHg?

Answer 17

100 mmhg

Question 18

Understanding the concept then when a patient stands, this adds 100 mmhg of hydrostatic pressure to the ankles, complete this equation,

If the hydrostatic pressure at the brachials is 110 standing up, what would the ankle pressure be?

Answer 18

210

Adding 100 to this.

Question 19

What word describes the “thickness” of the blood?

Answer 19

Viscosity.

Question 20

The thicker the fluid the “_____” ( greater, lesser) the friction and the “___” (greater/lesser) the energy loss

Answer 20

Thicker fluid=greater friction=greater energy loss

Question 21

When a patient has severe anemia, meaning less blood in the body, would this decrease or increase the viscosity or thickness of blood?

Answer 21

Decreases the viscosity. There is less of it therefore it isn’t as thick. The more blood the thicker it’ll be.

Question 22

What are the three main types of energy loss?

Answer 22

Friction, viscosity ( thickness of fluid), and intertia.

Question 23

How does friction loss occur? What happens as a result?

Answer 23

when one object rubs against another. This creates friction when the cells rub against each other; this converts energy to heat.

Question 24

Objects in motion stay in motion and objects at rest tend to stay at rest.

True False?

Answer 24

True.

Question 25

Once flowing, blood cells like to travel in a straight line unless an external force messes that up. How does this affect energy loss? Where can you sometimes see this at?

Answer 25

it creates energy loss when the speed or direction changes. At a vessel bifurication or stenosis.

Question 26

What is laminar flow?

Answer 26

Fluids flowing smoothly in an organized manner; evenly layered.

Question 27

What is the boundary layer in pertains to laminar flow (flow moving in a straight even line)

Answer 27

The layer of fluid along the vessel wall.

Question 28

Is the blood flow at the boundary layer usually faster or slower than the flow in the middle of the vessel?

Answer 28

Slow because its interacting with the wall creating friction (a form of energy loss)

Question 29

What are the two types of laminar flow?

Answer 29

Parabolic and plug flow.

Question 30

What is plug flow? What part of a vessel do you often seen this?

Answer 30

When the speed of blood in the middle of the vessel and the speed on the boundaries are almost similar in speed. Happens as bifurications and branches.

Question 31

What is parabolic fluid **most often seen)

Answer 31

Blood flow is faster in the middle of the vessel due to the drag of the wall on the blood (aka boundary layer)

Question 32

What are Eddys currents in relation to the boundary layer of a vessel?

Answer 32

Often blood flow wants to keep going in a straight line so when it gets to a biffurication it often continues this way creating a separation, that's when Eddy's currents come in and fill in the separation.

Question 33

Where is disturbed flow often seen in a vessel?

Answer 33

A stenosis or carotid bulb

Question 34

Disturbed flow ALWAYS means there is some sort of disease TRUE FALSE

Answer 34

False! Not always.

Question 35

What is turbulent flow?

Answer 35

flow that has varying directions and speeds. seen with disease

Question 36

What does the Reynolds number describe?

Answer 36

Predicts the point at which laminar flow becomes turbulent

Question 37

What is the Reynolds number?

Answer 37

>2000 <1500 is laminar >2000 is turbulent

Question 38

What are the two factors that affect resistance of flow?

Answer 38

The size of the vessel and the properties such as speed/thickness of blood

Question 39

If a vessel is long and contains thick blood , would there be more resistance or less and why?

Answer 39

MORE resistance, They are directly related.

Question 40

Resistance is_____ proportional to the vessel radius?

Answer 40

inversely When the radius diameter decreases, the resistance increases.

Question 41

What is Pouiselle's Law in relation to pressure and resistance? * Will come back with more info on this* * very important*

Answer 41

The resistance of flow through a vessel. Flow=pressure/resistance

Question 42

Of all the factors of Pouiselle's Law, which is the most important? A)Thickeness of the blood B) Diameter change/Radius C)length of the vessel

Answer 42

RADIUS.

Question 43

Think of this analogy Honey moving through a very long straw...will there be a lot of resistance or no?

Answer 43

yes. Honey is THICK, and if it has a long way to travel and is thick, it'll have a lot of resistance coming out

Question 44

Water through a large/wide diameter pipe will have more resistance or less?

Answer 44

Less. Water isn't think and it has wide pipe to go through. Easy.

Question 45

What does the Dicrotic notch represent? | When does it occur? in the end diastole, early systole or early diastole?

Answer 45

The aortic valve closing. (temporary reversed flow) Happens in the early diastole

Question 46

In the early systole, the aortic valve is opening or close?

Answer 46

Opening

Question 47

What kind of arteries have low resistance flow?

Answer 47

IMPORTANT ONES such as the carotid ICA and renal veins.

Question 48

What type of arteries have high resistance flow?

Answer 48

Carotid ICA/Legs/Arms Not as important ones

Question 49

Low resistive flow means it needs constant flow where as high resistive doesn't need as constant of flow. Low resistive is more important True/False

Answer 49

True

Question 50

Little to no diastole is seen in ___ resistive vessels

Answer 50

High resistive

Question 51

Area and velocity are _____ proportional

Answer 51

Inversely.

Question 52

Smaller diameter vessel means faster speed. True or False?

Answer 52

True

Question 53

Within the area of a stenosis, what kind of waveform should you expect?

Answer 53

In a stenosis the vessel is getting narrower therefore it speeds up ( higher velocity) and spectral broadening.

Question 54

Proximal to a stenosis, what kind of waveform should you expect?

Answer 54

Often dampened

Question 55

Distal to a stenosis what kind of waveform should you expect?

Answer 55

Flow reversel, turbulence, eddy currents.

Question 56

If there is a HEMODYNAMICALLY SIGNIFICANT stenosis seen, ( such as 50% diameter reduction), what kind of pressure will you see? Decreased or increased?

Answer 56

decreased pressure. **50 % diameter reduction = 75% area reduction

Question 57

Explain Bernoulli's principle? It is the relationship between ____ and _____.

Answer 57

Relationship between pressure and speed (velocity). Higher pressure lower speed Low pressure- higher speed.

Question 58

Is velocity and pressure directly or inversely proportional?

Answer 58

Inversely As speed/velocity increases the pressure decreases As velocity decreases, pressure increases.

Question 59

Which one of these will have a higher velocity and why? an ICA stenosis or aortic aneurysm?

Answer 59

The ICA will have higher velocity because the vessel is narrower and speed goes faster through a narrower vessel. ** as area decreases, velocity increases***

Question 60

Which one of these will have the lowest pressure and why? an ICA stenosis or aortic aneurysm?

Answer 60

The ICA stenosis will have the lowest pressure because speed and pressure are inversely related.

Question 61

An arterial occlusion or stenosis may result in ______ (decreased/increased) pressure distally

Answer 61

Decreased. ** remember bernoullis rule of speed being inversely related to pressure. Stenosis has higher speed, therefore pressure is decreased.

Question 62

What does the vessel do anytime blood flow is reduced to the point it cannot accommodate the demand? *Think about bernoullis again. If the pressure gets low, the vessel will do this to increase the pressure **

Answer 62

Vasodilatation * page 25 in book**

Question 63

What is autoregulation?

Answer 63

the ability for most vascular beds to maintain a constant flow

Question 64

What are vasoconstriction and vasodilation controlled by? **which part in brain**

Answer 64

Sympathetic nervous system

Question 65

What is the difference in waveform if a complete artery occlusion has collateralization versus if it doesn't?

Answer 65

With collateralization- this allows adequate blood flow, no dilatation, minimally altered Without collateralization- inadequate blood flow, decreased pressure therefore vasodiliataion will occur.

Question 66

During exercise does vasoconstriction or vasodilatation occur?

Answer 66

vasodilatation. More blood is needed for exercise, so the arterial bed will dilate to allow blood flow.

Question 67

If the blood pressure drops, the arteries will _______ (dilate/constrict) allowing for constant blood flow volume.

Answer 67

Vasodilation.

Question 68

If the blood pressure drops, the arteries will (dilate/constrict) allowing a steady blood flow volume.

Answer 68

Vasoconstriction.

Question 69

An increased heart rate delivers what?

Answer 69

an increase in blood volume

Question 70

What is the heart pump?

Answer 70

it generates the pressure to move to the blood

Question 71

Explain the process of how cardiac contraction works?

Answer 71

1) pressure in the left ventricle arises rapidly 2) Left ventricle pressure exceeds that than in the aorta 3) aortic valve opens, blood is ejected, BP rises

Question 72

What does the cardiac contraction do?

Answer 72

it distends the arteries, which serve as a reservoir and source of potential energy

Question 73

How is flow rate and resisitance related? Inversely or directly/

Answer 73

Inversely

Question 74

What is the HP is the ankle when a patient is standing?

Answer 74

100

Question 75

What is the HP in the ankle when a patient is supine?

Answer 75

0

Question 76

internal friction within a fluid is measured by what/

Answer 76

viscosity ( thickness of the blood)

Question 77

What is the relationship between velocity and viscosity?

Answer 77

inversely

Question 78

What is laminar flow?

Answer 78

layers of fluid particles moving against one another

Question 79

What is low resistance flow?

Answer 79

Flow of continuous steady nature feeding a dilated vascular bed...needs CONSTANT flow

Question 80

What vessels are low resistive?

Answer 80

ICA, vertebrals, renal, celiac, splenic, hepatic, non-fasting SMA

Question 81

What is high resistance flow?

Answer 81

flow of pulsatile nature. * between indident pulses, hydraulic reflections travel back up the vessel from the periphery producing flow reversals in the vascular compartment * doesn't need constant flow*

Question 82

What vessels are high resisitive

Answer 82

ECA , subclavian, aorta, iliac, extremity arteries, fasting SMA

Question 83

What can happen to the reversal component of a high resistant signal distal to a stenosis?

Answer 83

It may disappear due to decreased peripheral resistance, secondary to ischemia

Question 84

What does the doppler flow distal to a stenosis look like?

Answer 84

Low resistant, more rounded in appearance, and weaker in strength, tardus parvus!

Question 85

What happens when a high resistance wave form approaches a stenosis?

Answer 85

it can go from triphasic to monophasic

Question 86

as the inflow pressure falls as a result of a stenosis, what is the peripheries natural response? Vasodilate or vasoconstrict?

Answer 86

vasodilate

Question 87

True or False The location of collaterals help provide tenative location of the obstruction

Answer 87

true

Question 88

What changes when BP rises?

Answer 88

constriction of vessels

Question 89

What happens when BP falls?

Answer 89

dilation of vessels

Question 90

What happens when cross sectional area reduction of 75%

Answer 90

Diameter reduction by 50%

Question 91

Where are the lower frequencies distributed?

Answer 91

The walls/boundary layer

Question 92

What happens pre-stenosis?

Answer 92

flow frequencies are dampened

Question 93

What happens at stenosis?

Answer 93

increase in frequencies, spectral broadening and elevated velocity