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Phys III > Exam II Circ > Flashcards

Exam II Circ Flashcards

1
Q

In most tissue beds, blood flow is regulated in proportion to what?

A

Local metabolism

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2
Q 
Consider the resistance in the following tissue beds: 
Coronary= .40 mmHg/ml/min
Brain= .13 mmHg/ml/min
Liver= .08 mmHg/ml/min
Kidneys= .10 mmHg/ml/min

What is the total peripheral resistance?

A

Less than .08

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3
Q

Using the data from the previous question, which tissue bed would have the greatest flow (lowest resistance)?

A

Liver

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4
Q

In the following vessels, the flow rate is identical, which vessel is offering the greatest resistance to flow?
A. P1=50 P2=25
B. P1=70 P2=60
C. P1=80 P2=65

A

A. P1=50 P2=25

The greatest change in pressure = the greatest resistance (occurs in arterioles)

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5
Q

A broad band Doppler reading is indicative of what type of flow?

A

Turbulent

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6
Q

If a vessel with a length of 100cm has a cross-sectional area of .5cm2, and velocity of flow of 10cm/sec, and the pressure drop across that length is 10mmHg, what is the flow in that vessel?

A

300ml/min

.5cm2 x 10cm/sec = 5ml/sec x 60= 300ml/min

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7
Q

The vascular compartment with the greatest total cross-sectional area is what?

A

Capillaries

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8
Q

What are characteristics of parallel circuitry?

A

Independent of flow control, maximizes oxygen delivery to tissues, and decreases work load on the heart, minimizes TPR

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9
Q

A small change in volume producing a large change in pressure is characteristic of which vascular compartment?

A

Systemic arteries

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10
Q

Acetylcholine binding to the vascular endothelium has what effect?

A

Vasodilatation by causing nitric oxide release

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11
Q

What is the effect of sympathetic nervous stimulation on most vascular smooth muscle?

A

Vasoconstriction mediated by alpha receptors

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12
Q

During widespread sympathetic nervous system stimulation, which tissue bed would show the least increase in vascular resistance?

A

Lung

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13
Q

As a tissue becomes more active, how is blood flow to that tissue increased?

A

Tissue releases local vasodilators

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14
Q

At a given mean circulatory filling pressure what happens to venous return as central venous pressure increases?

A

Venous return decreases

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15
Q

If cardiac output is stopped, arterial pressure will be expected to fall until it equals what?

A

Critical closing pressure

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16
Q

In a healthy young adult comment about tissue flow during diastole.

A

Maintained by recoil of the arteries

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17
Q

If blood flow to a tissue doubles from 200ml/min to 400ml/min, and the AV O2 difference falls from .05ml O2/ml to .025ml O2/ml, comment on the increase in flow.

A

It is likely due to shunting (through the capillary beds)

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18
Q

What increases the plasma colloid osmotic effect by about 50%?

A

Negative changes on protein attracting and holding positive ions like sodium

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19
Q

What effects are attributed to slow breathing?

A

Increased resting oxygen saturation, decreased chemoreflex activation, decreased mean arterial blood pressure

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20
Q

What effect does decreasing velocity have on blood viscosity?

A

Increases

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21
Q

How does fibrinogen decrease blood viscosity?

A

Makes RBC’s more flexible

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22
Q

Use the following graph to answer the following questions.

              \
                 \
VR                 \
                            \
                                 \
		0	5	10	CVP
Considering vascular function as central venous pressure increases, what happens to venous return?

What is the mean circulatory filling pressure equal to?

A

Decreases; 10mmHg

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23
Q

The chronic use of anti-inflammatory drugs could be expected to inhibit what process?

A

Angiogenesis

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24
Q

Consider the following data:

average capillary hydrostatic P = 17 mmHg
average capillary colloid osmotic P = 28 mmHg
average interstitial hydrostatic P = -2 mmHg
average interstitial colloid osmotic P = 9 mmHg

a. filtration > reabsorption
b. filtration
A

C. Filtration = reabsorption

Net filtration = (17- -2) - (28-9) = 0

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25
Q

Which brainstem area is tonically active and is associated with a tonic SNS outflow?

A

Neurons anterolateral in the upper medulla and pons

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26
Q

Which substances are associated with local vasodilatation?

A

Adenosine, CO2, K+, histamine and lactic acid

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27
Q

What high-resistance microvessels control local blood flow by integrating multiple input which determines lumen diameter?

A

Arterioles

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28
Q

Compare the distensibility of the following vessels.
Vessel one: Vessel two:
Orig vol. = 20 ml Orig vol. = 10 ml
/\ vol = 1 ml /\ vol = 1 ml
/\ pressure = 2 mmHg /\ pressure = 2 mmHg

a. vessel one is more distensible than vessel two
b. vessel two is more distensible than vessel one
c. vessel one and vessel two are equally distensible
A

B. Vessel 2 is more distensible than vessel 1

V1: 1ml/(2mmHg20ml) = 1/40
V2: 1ml/(2mmHg10ml) = 1/20 (higher)

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29
Q

What may act at the level of the CNS in the development of hypotension?

A

NO and serotonin

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30
Q

In the kidney, how dos SNS stimulation increase angiotensin formation?

A

By stimulation of the JG cells to release renin

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31
Q

In response to a fall in systemic arterial blood pressure, what changes would be counterproductive in offsetting that fall?

A

Increase in ANP release

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32
Q

In the face of rising arterial blood pressure, what response would autoregulate both renal blood flow and glomerular filtration?

A

Constriction of the afferent arterioles

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33
Q

What effect does stimulation of baroreceptors have on sympathetic outflow?

A

Decreases

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34
Q

During systole, what is happening to baroreceptor activity?

A

Increasing

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35
Q

In the fetus, the ductus arteriosis shunts blood from the pulmonary artery to the aorta returning primarily from what vessel?

A

Superior vena cava

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36
Q

What is the function of the ductus venosus in the fetus?

A

Shunt blood from the umbilical vein into the inferior vena cava (bypasses liver)

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37
Q

In which tissue bed does SNS stimulation cause a metabolically-induced local increase in blood flow?

A

Heart

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38
Q

During exercise, what normally decreases?

A

VO2 and TPR

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39
Q

During exercise, most of the increase in cardiac output is due to which of the following?

A

Increase in heart rate

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40
Q

What is the main function of systemic circulation?

A

To deliver adequate oxygen and nutrients and remove CO2 and other waste from systemic tissues

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41
Q

True/False: Blood flow is proportional to metabolic demand.

A

True

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42
Q

What are the 4 components that make up vessels?

A

Endothelium, elastic tissue, smooth muscle, fibrous tissue

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43
Q

The aorta contains more _____, a typical artery contains more _____, while capillaries contain _____.

A

Elastic tissue; smooth muscle; endothelium only

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44
Q

What is the equation for Ohm’s Law?

A

V = IR

V is voltage
I is current flow
R is resistance

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45
Q

Ohm’s law is analogous to?

A

/_\ P = FR

P is pressure gradient
F is flow
R is resistance

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46
Q

Flow is equal to:

A

Velocity x Cross-sectional area

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47
Q

Where does the greatest resistance to flow occur?

A

Pre-capillary resistance vessels (arterioles, metarterioles, precapillary sphincters)

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48
Q

Resistance is equal to:

A

8nl/Pir4

n is viscosity
l is length of vessel
r is radius

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49
Q

Systemic circulation is predominantly a _____ circuit.

A

Parallel

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50
Q

What is the normal range of hematocrit?

A

38-45%

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51
Q

A narrow band Doppler reading indicates what type of flow?

A

Laminar flow

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52
Q

Reynold’s number describes:

A

The probability statement for turbulent flow (the greater the number, the greater the probability of turbulence)

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53
Q

If Reynold’s number (R#) is

A

Laminar

54
Q

If R# is >3000, flow is usually:

A

Turbulent

55
Q

Fick’s Principal describes:

A

Blood flow to a tissue/organ

56
Q

What is distensibility?

A

Ability of a vessel to stretch/distend

57
Q

What is compliance?

A

Ability of a vessel to stretch and hold volume

58
Q

True/False: Systemic arteries are more compliant than veins.

A

False, veins are 24x more compliant

59
Q

True/False: Veins are more distensible than systemic arteries.

A

True (8x more)

60
Q

During chronic exercise, most of the increase in cardiac output is due to:

A

Increase in stroke volume

61
Q

In the face of falling arterial blood pressure, which response would autoregulate both renal blood flow and glomerular filtration?

A

Dilation of the afferent arterioles

62
Q

What causes the release of VEGF?

A

Hypoxia

63
Q

What are the mechanical triggers for angiogenesis?

A

Hemodynamic and shear stress

64
Q

What are the chemical triggers for angiogenesis?

A

Hypoxia and NO

65
Q

What are the molecular triggers for angiogenesis?

A

Decreased glucose, inflammation and angiogenic growth factors

66
Q

The vasoactive role of endothelium includes releasing what?

A

Prostacyclin, NO, and endothelin

67
Q

Oxygen uptake is determined by what calculation?

A

O2 uptake = F x (A-V O2 difference)

68
Q

What is the most common plasma protein in circulation?

A

Albumin

69
Q

The reflection coefficient expresses:

A

How readily protein can cross the capillary wall

70
Q

If the reflection coefficient is 0:

A

All colloid proteins freely cross the capillary wall

71
Q

If the reflection coefficient is 1:

A

All colloid proteins are reflected, none cross the capillary wall

72
Q

What is responsible for draining excess fluid from interstitial spaces?

A

Lymph capillaries

73
Q

2/3 of all lymph comes from:

A

Liver and intestines

74
Q

If cardiac output is stopped, what effects will be observed?

A

Arterial pressure will fall and venous pressure will rise

75
Q

The equalibration pressure where arterial BP is equal to venous BP is called:

A

Mean circulatory filling pressure

76
Q

Which brainstem area has vasodilatory effects and decreases cardiac activity?

A

Neurons anterolateral in the lower M.O.

77
Q

Neurons in the posterolateral portions of the pons and medulla are associated with what area?

A

Sensory area (A2)

78
Q

The sensory area of the vasomotor center receives input primarily from what cranial nerves?

A

CN IX and X

79
Q

Baroreceptors are especially abundant in:

A

Carotid sinus and arch of aorta

80
Q

True/False: Baroreceptors are more sensitive to changing pressure than static pressure.

A

True

81
Q

What are specialized peritubular capillaries associated with juxtamedullary neurons?

A

Vasa recti

82
Q

What hormones decrease renal blood flow?

A

Norepinephrine, epinephrine and angiotensin II

83
Q

What hormones increase renal blood flow?

A

Prostaglandins (E & I)

84
Q

The RAA system is stimulated by:

A

Decreased perfusion pressure, SNS stimulation, decreased NaCl delivery and hormones (thyroid & growth)

85
Q

Renin is an enzyme that catalyzes the formation of _____ from _____.

A

Angiotensin I from angiotensinogen

86
Q

The conversion of angiotensin I to angiotensin II occurs primarily in the:

A

Lung

87
Q

What is the effect of tying off one renal artery?

A

Development of systemic hypertension

88
Q

What is the effect of tying off a renal artery and removing a kidney?

A

No development of HTN or uremia

89
Q

What is the effect of tying off a renal artery and removing both kidneys?

A

Development of both HTN and uremia

90
Q

Hypertension generated by tying off a renal artery is called:

A

Goldblatt hypertensive model

91
Q

What allows blood to bypass the lungs?

A

Ductus arteriosis and foramen ovale

92
Q

What allows umbilical and portal blood to bypass the liver?

A

Ductus venosus

93
Q

Blood from which source in the fetus is most saturated with oxygen?

A

Umbilical vein (80%)

94
Q

Which tissues escape SNS vasoconstriction?

A

Heart, brain and lungs

95
Q

Which CV endpoint decreases with exercise?

A

Total peripheral resistance

96
Q

Extra O2 is used to:

A

Restore metabolite levels and metabolize lactate generated by glycolysis

97
Q

True/False: Arterial pressure control is independent of both local flow and cardiac output.

A

True

98
Q

In which vessel would velocity of flow be slowest?

A

Inferior vena cava

99
Q

Blood flow to most tissues or organs is regulated in proportion to:

A

Metabolic demand

100
Q

If the flow in a vessel is 20cm/sec and the cross-sectional area is .1cm2, what is the flow rate?

A

120ml/min

101
Q

Which groups of vessels regulate blood flow to an organ?

A

Arterioles

102
Q

What effect does fibrinogen have on the viscosity of blood?

A

Decreases viscosity

103
Q

A broad band Doppler reading is obtained over the right carotid artery. What is the significance of this finding?

A

Partial occlusion

104
Q

Angiogenesis can be impaired by:

A

Anti-inflammatory drugs

105
Q

In cardiac failure, what happens to central venous pressure?

A

Increases

106
Q

All else being equal, what effect would a decrease in TPR have on diastolic BP?

A

Decreased

107
Q

When would venous return be stopped?

A

If CVP is equal to MCFP

108
Q

A vessel has an original volume of 20ml. As volume is increased 5ml, pressure is increased to 2mmHg. Calculate the distensibiility.

A

.125

Distensibility = change in vol/change in pressure x original vol

D = 5/(2 x 20) = .125

109
Q

As a tissue becomes more active, what is the primary way local blood flow increases?

A

Release of local vasodilators

110
Q

What receptor mediates the SNS vasoconstrictor response?

A

Alpha

111
Q

How does circulating Ach cause local dilation of vascular smooth muscle in a tissue bed?

A

Binds to endothelium causing release of NO

112
Q

During ejection of blood, comment on baroreceptor activity.

A

Increasing

113
Q

If blood flow to a tissue doubles, but AV O2 difference falls by 1/2, what happened?

A

It is likely due to shunting

114
Q

If blood flow to a tissue is 400ml/min, the AO2 is .2ml O2/ml and VO2 is .1ml O2/ml, what is the O2 uptake?

A

40ml/min

F = 400 x (.2 - .1)

115
Q

Using indicator dilution to determine cardiac output, as the duration of the curve increases, what is happening to the cardiac output?

A

Decreases

116
Q

In the brain, how is excess plasma filtrate returned to the vascular system?

A

Via the arachnoid villi

117
Q

What is “hydraulic filtering?”

A

Stretch and recoil of the arterial tree during the cardiac cycle

118
Q

If one renal artery was stenotic, what would be expected?

A

Development of HTN and elvated angiotensin II levels

119
Q

What is the mechanism by which SNS stimulation to the heart cause local vasodilation of coronary vascular smooth muscle?

A

Norepinephrine stimulation of cardiac cells which release adenosine

120
Q

Which area of the vasomotor center is tonically active and provides basal stimulation of the SNS?

A

Pressor center

121
Q

In response to a rise in extracellular fluid levels, which change would be counterproductive in keeping BP from rising?

A

Decreased arterial naturectic peptide release

122
Q

In the fetus, what is the function of the ductus venosus?

A

Allows blood returning from placenta to bypass the liver and flow into the inferior vena cava

123
Q

In the fetus, the blood that shunts through the ductus arteriosis is returning from which location?

A

Head

124
Q

Slow breathing has been shown to decrease both systolic and diastolic BP due to:

A

Decreasing sympathetic activity

125
Q

What will not increase venous return during exercise?

A

Increased central venous pressure

126
Q

As total cross-sectional area decreases, what happens to the velocity of flow?

A

Increases

127
Q

Under strong widespread SNS stimulation, which tissue bed would show the greatest increase in blood flow?

A

Heart

128
Q

A large increase in local tissue flow due to an increase in metabolic activity is usually associated with what changes?

A

Vasodilation of pre-capillary resistance vessels

129
Q

Which change is associated with a decrease in the viscosity of the blood?

A

Fahreus-Lindquist effect

130
Q

True/False: Total peripheral resistance is always less than total coronary resistance.

A

True

Phys III (3 decks)

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