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Physiology III Exam 2 > Flow > Flashcards

Flow Flashcards

1
Q

What is flow?)

A

The volume of blood that passes a certain point per unit time (ml/min
F = velocity x cross sectional area
F = change in P/ R

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2
Q

What is the driving force of blood?

A

Pressure gradient

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3
Q

What is a pressure gradient and what is it proportional to?

A

The difference in pressure between 2 points

Proportional to flow (F)

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4
Q

Where does the greatest resistance to flow occur?

A

Pre-capillary resistance vessels

-Arterioles, metarterioles, precapillary sphincters

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5
Q

What is the equation for resistance?

A 
R = 8nI/pi r^4
n = viscosity 
l = length of vessel
r = radius
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6
Q

What is a parallel circuit?

A

1/RT = 1/R1 + 1/R2 + 1/R3……. or RT = 1/ ((1/R1) + (1/R2) + (1/R3))
RT

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7
Q

What is a series circuit?

A 
RT = R1 + R2 + R3
RT = sum of individual Rs
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8
Q

What kind of circuit is systemic circulation?

A

Predominantly parallel

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9
Q

What are 3 advantages of parallel circulation?

A
  1. Independence of local flow control
  2. Minimizes total peripheral resistance
  3. Oxygen rich blood supply to every tissue
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10
Q

What is total vascular resistance (TVR) equal to?

A

the sum of total pulmonic resistance + total peripheral resistance
because pulmonic and systemic circulations are in series with one another

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11
Q

What is viscosity?

A

Internal friction of a fluid associated with the intermolecular attraction

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12
Q

What is the viscosity of blood?

A

3 (most due to RBCs)

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13
Q

What is the viscosity of plasma?

A

1.5

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14
Q

What is the viscosity of water?

A

1

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15
Q

With blood, is viscosity proportional to velocity?

A

No, inversely proportional

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16
Q

What are the 3 viscosity considerations at microcirculation?

A
  1. Velocity decreases which increases viscosity
  2. Cells can get stuck at constriction points which increases viscosity
  3. Cells line up which decreases viscosity and offsets 1 and 2
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17
Q

What is hematocrit?

A

Percentage of packed cell volume (primarily RBCs)

normal = 38-45%

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18
Q

What are characteristics of laminar flow?

A

Streamline
Silent
Most efficient
Normal

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19
Q

What are characteristics of turbulent flow?

A 
Cross mixing
Vibrational noise
Least efficient
Frequently associated with vessel disease (bruit)--thrombus
Partially occluded vessels
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20
Q

What is Reynold’s number?

A 
Probability statement for turbulent flow
R# = vDp/n
v = velocity
D = tube diameter
p = density
n = viscosity
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21
Q

The greater the R#, the greater the probability for….?

A

Turbulance

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22
Q

If R#

A

Laminar

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23
Q

If R# > 3000, flow is usually laminar or turbulent?

A

Turbulent

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24
Q

What is a doppler ultrasonic flow-meter used for?

A

To determine velocity of flow

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25
Q

RBCs moving towards the doppler transmitter compress sound waves, therefore increasing or decreasing frequency of returning waves?

A

Increasing

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26
Q

Broad band is associated with laminar or turbulent flow?

A

Turbulent

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27
Q

Narrow band is associated with laminar or turbulent flow?

A

Laminar

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28
Q

What 2 things do we use to determine cardiac output?

A

Fick principle and indicator of dilution

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29
Q

What 3 things do we use to determine vessel flow?

A

Venous occlusion plesthymography
Doppler ultrasonic flowmeter
Vascular flow cuffs

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30
Q

What are the 3 parts to the Fick principle?

A

Input blood concentration of substance
output blood concentration of substance
Addition/removal of substance from tissue

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31
Q

Flow = ?

A

amount of substance per min / AV difference

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32
Q

Pulmonary blood flow = ?

A

Cardiac output

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33
Q

What is indicator of dilution?

A

A way to determine flow based on the area under the curve
-Inject dye, measure volume under curve
-Based on conservation of mass
CO is inversely proportional to average duration of the curve (dye concentration)

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34
Q

Is CO proportional to average duration of the curve (dye concentration) in indicator dilution?

A

No, inversely proportional

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35
Q

What is distensibility?

A

The ability of a vessel to stretch

Change in volume / change in pressure x initial volume

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36
Q

What is compliance?

A

The ability of a vessel to stretch and hold volume
Change in volume / change in pressure
Distensibility x initial volume

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37
Q

Is compliance = distensibility?

A

No

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38
Q

Is compliance proportional to distensibility?

A

Yes

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39
Q

In systemic arteries, a small change in volume is associated with a large change in ….?

A

pressure

40
Q

In systemic veins, a large change in volume is associated with a small change in ….?

A

pressure

41
Q

Veins are how much more distensible and compliant than systemic arteries?

A

8 x more distensible
3 x larger
24 x more compliant

42
Q

Local blood flow is regulated in proportion to what?

A

metabolic demand in most tissues

43
Q

What does short term control of blood flow involve?

A

Vasodilation/vasoconstriction of precapillary resistance vessels

44
Q

What is long term control of blood flow involve?

A

Changes in tissue vascularity

  • Formation/dissolution of vessels
  • Vascular endothelial growth factor and angiotenin
45
Q

What is the role of arterioles in control of flow?

A
  • Integrator of multiple inputs
  • Innervated by SNS vasoconstrictor fibers and have alpha receptors
  • Effected by local factors (vasodilators, circulating substances)
46
Q

When pressure is kept relatively constant, vasodilation will result to what changes in resistance and flow?

A

Decreased resistance leads to increased flow

47
Q

When pressure is kept relatively constant, vasoconstriction will result to what changes in resistance and flow?

A

Increased resistance leads to decreased flow

48
Q

What is the local vasodilator theory?

A

Active tissues release local vasodilator (metabolites) which relax vascular smooth muscle

49
Q

What is the oxygen demand theory?

A

As tissue uses up oxygen, vascular smooth muscle cannot maintain constriction

50
Q

What is autoregulation?

A

The ability to keep blood flow (F) constant in the face of a changing arterial BP

51
Q

Are renal flow and glomerular filtration rate autoregulated?

A

Yes

52
Q

What is angiogenesis?

A

Production of new microvessels

53
Q

What is arteriogenesis?

A

Shear stress caused by enhanced blood flow velocity associated with partial occlusion

54
Q

What are angiogenic factors?

A

Small peptides that stimulate growth of new vessels

-Vascular endothelial growth factor (VEGF)

55
Q

What is up-regulated when endothelium is activated by stress?

A

Monocyte chemoattractant protein-1 (MCP-1)

  • Inflammation
  • Remodeling and development of new and enlarged collateral arteries and arterioles
56
Q

Hypoxia causes release of what peptide?

A

VEGF

57
Q

What does VEGF stimulate?

A

capillary proliferation and development of collateral arterial vessels

58
Q

Is NPY from SNS angiogenic?

A

Yes

59
Q

What may hyperactive SNS compromise?

A

Collateral blood flow by vasoconstriction

60
Q

What is vasculogenesis?

A

Mesenchymal cell differentiate into endothelial cells

61
Q

What is angiogenesis?

A

Formation of new blood vessels by sprouting from pre-existing small vessels usually lacking developed tuinca media

62
Q

What is arteriogenesis?

A

Rapid proliferation of pre-existing collateral vessels with fully developed tunica media

63
Q

What are the 3 types of angiogenesis triggers?

A

Mechanical, chemical, and molecular

64
Q

What are the mechanical angiogenesis triggers?

A

Hemodynamic

Shear stress

65
Q

What are the chemical angiogenesis triggers?

A

Hypoxia

NO

66
Q

What are molecular angiogensis triggers?

A 
Decreased glucose -- increased VEGF
Inflammation
angiogenic growth factors
-Fibroblast gf
-VEGF
-Placenta gf
-angiopoietin
67
Q

What is therapeutic angiogensis?

A

Clinical enhancement/promotion of collateral blood vessels/flow in ischemic tissues

68
Q

What are the 3 methods of therapeutic angiogenesis?

A
  1. Protein therapy (use GF proteins)
  2. Gene therapy (manipulate gene expression)
  3. Cellular therapy (introduce angiogenic factors)
69
Q

What are 3 things that endothelium release to give it a vasoactive role?

A 
Prostagyclin (PGI2)
Nitric Oxide (NO)
Endothelin
70
Q

What does prostacyclin do?

A

Inhibit platelet aggregation

Relaxes vascular smooth muscle

71
Q

What does nitric oxide do?

A

Vasodilator
Stimulated by shear stress associated with increased flow
and acetelcholine binding to endothelium

72
Q

What is the functional unit of the circulation where the bulk of exchange takes place?

A

Capillary

73
Q

What is vasomtion?

A

The intermittent contraction of metarterioles and precapillary sphincters

74
Q

What are 3 mechanisms of exchange in microcirculation?

A

Diffusion
Ultrafiltration
Vesicular transport

75
Q

What are 2 ways that blood can bypass the capillary bed and go straight to the venule?

A

AV shunt

Metarteriole

76
Q

What is oxygen uptake equal to?

A

the product of flow (F) x the arterial-venous oxygen difference
O2 uptake = (F)(A-VO2 difference)

77
Q

Functional/nutritive flow (F) is associated with increased what?

A

Oxygen uptake/utilization

78
Q

Non-nutritive flow increases is associated with what?

A

Shunting of blood through a bed

79
Q

What does passive diffusion require?

A

Permeability

Concentration gradient

80
Q

What does ultrafiltration require?

A

Bulk of flow goes through filter (capillary wall)
Starling forces
-Hydrostatic pressure
-Colloid osmotic pressure

81
Q

What does vesicular transport require?

A

Larger molecular weight non-lipid soluble substances

82
Q

Does hydrostatic pressure gradient favor filtration or reabsorption?

A

Filtration

83
Q

Does colloid osmotic pressure (low to high) favor filtration or reabsorption?

A

Reabsorption

84
Q

What is the equation for net filtration pressure?

A

(capillary hydrostatic pressure-interstitial hydrostatic pressure) - (capillary colloid osmotic pressure-interstitial colloid osmotic pressure)

85
Q

The colloid osmotic pressure is a function of what?

A

protein concentration

albumin, globulins, fibrinogen

86
Q

What is the calculated colloid effect?

A

19 mmHg

87
Q

What is the actual colloid effect?

A

28 mmHg

88
Q

What is the discrepancy between calculated and actual colloid effect due to?

A

Donnan effect

89
Q

What effect does the Donnan Effect have on colloid osmotic effect? (increase or decrease)

A

Increase

90
Q

How does the Donnan effect increase colloid osmotic effect?

A

Large molecular weight proteins (albumin) carry negative charges which attract positive ions. This increases the osmotic effect by 50%

91
Q

Where would we find tight junctions in capillary walls?

A

Blood brain barrier

92
Q

Where would we find discontinuous junctions in capillary walls?

A

Liver

93
Q

Where would we find filtration slits (fenestrations) in capillary walls?

A

Glomerular capillaries

94
Q

What kind of protein can exert osmotic pressure?

A

That protein that cannot cross capillary wall

95
Q

What does the reflection coefficient express?

A

How readily protein can cross a capillary wall

0-1

96
Q

What does a reflection coefficient of 0 mean?

A

All colloid proteins freely cross wall, none are reflected = no colloid effect

97
Q

What does a reflection coefficient of 1 mean?

A

All colloid proteins are reflected, none cross capillary wall = full colloid effect

Physiology III Exam 2 (7 decks)

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