Cardiology 4: Vascular System Flashcards

1
Q

what is flow (q)

A

volume of fluid displaced through a vessel with respect to time (L/min)

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2
Q

flow is determined by what 2 things?

A
  1. pressure difference (Pi - Po)

2. resistance (R) across a vessel

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3
Q

resistance is ____ proportional to flow

A

inversely

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4
Q

pressure difference is ____ proportional to flow

A

directly

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5
Q

resistance is primarily determined by the ____ of the vessel

A

radius

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6
Q

a small change in radius results in a ___change in resistance

A

very large

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7
Q

whenever the radius decreases, the flow decreases to the power of ___

A

4

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8
Q

what is velocity?

A

distance fluid travels along a vessel with respect to time

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9
Q

velocity is determined by what 2 things?

A
  1. flow through the vessel

2. cross-sectional area of vessel

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10
Q

velocity is ____ proportional to flow

A

directly

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11
Q

veloccity is ____ proportional to cross sectional area

A

inversly

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12
Q

as the cross-sectional area increases, the velocity of blood ____

A

decreases

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13
Q

vasculature plays an active role in regulating ____ and ___ for efficient matching of flow and demand

A

blood pressure and distribution of flow

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14
Q

each vessel type has a specific function that is determined by its ____

A

structure

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15
Q

structural feature of arteries

A

elastic

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16
Q

structural feature of arterioles

A

can change radius

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17
Q

structural feature of capillaries

A

material exchange

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18
Q

structural feature of veins

A

expandable

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19
Q

what is the one common structural feature of all the vasculature of the circulatory system?

A

a smooth, single-celled layer of endothelium

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20
Q

___ arteries have thick walls with 3 layers

A

systemic

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21
Q

what are the 3 layers of the systemic arteries?

A
  1. intima
  2. media
  3. adventitia
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22
Q

describe the structure of the intima

A

single layer of endothelial cells acting as a metabolically active barrier between blood and the vessel wall

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23
Q

describe the structure of the media

A

thick layer of elastin and collagen (strength) and vascular smooth muscle (for contraction)

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24
Q

there are 2 main structures of arteries that give them their characteristic functions, what are these structures and their functions?

A
  1. large radius: low resistance tubes conductine blood to organs
  2. elasticity: pressure reservoir for maintaining blood flow during diastole
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25
Q

the arteries store ___ to maintain blood flow during diastole

A

pressure

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26
Q

what is the function of arterioles?

A

regulate rate and distribution of blood flow

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27
Q

arterioles are composed of ___ and ____ arranged in rings that allow for vasoconstriction and vasodilation

A

endothelium and smooth muscle

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28
Q

what are the 2 control systems of the arterioles and what systems control those systems?

A
  1. Intrinsic (local conditions surrounding BV control)

2. extrinsic (nervous system input controls)

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29
Q

what are the 3 sources of intrinsic control of blood flow?

A
  1. autoregulation / myogenic regulation
  2. endothelium-mediated regulation
  3. metabolic regulation
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30
Q

in autoregulation / myoregulation, blood flow is adjusted to _____ based on _____

A

local pressure; vessel stretch

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31
Q

in autoregulation / myoregulation, changes in local blood pressure cause changes in arteriolar radius and resistance to maintain _____

A

stable local flow

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32
Q

arterioles ___ with increased local blood flow and ____ with decreased pressure

A

constrict; dilate

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33
Q

in endothelium mediated regulation, endothelium lining produces substances that ___ or ___ arteriole smooth muscle

A

relax; contract

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34
Q

give 2 substances that the endothelium produces to induce relaxation of arteriole smooth muscle

A

nitric oxide; prostacyclin

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35
Q

give 2 examples of substances that the endothelium produces to induce contraction of the ateriole smooth muscle

A

angiotensin 2 and endothelin

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36
Q

in metabolic regulation, inadequate O2 supply by increased metabolic rate or decreased O2 delivery results in accumulation of ___ which locally ____ the arterioles

A

metabolites; dilates

37
Q

give 4 examples of metabolites that can accumulate in metabolic regulation

A
  1. lactic acid
  2. CO2
  3. H+
  4. adenosine
38
Q

what are the 3 sources of extrinsic control of flow?

A
  1. sympathetic regulation
  2. hormonal regulation
  3. reflex regulation
39
Q

sympathetic regulation involves what areas of the cerebral medulla to influence vessel tone?

A
  1. pressor region

2. depressor region

40
Q

stimulation of the pressor region causes____ resulting in ___

A

sympathetic outflow; vasoconstriction

41
Q

stimulation of depressor region causes ____ resulting in ___

A

inhibition of pressor region, resulting in vasodilation

42
Q

what 2 hormones released by the adrenal medulla influence arteriole tone?

A

NE and Epi

43
Q

a low concentration of Epi causes ___ of arterioles by stimulating ___ receptors

A

dilation ; beta

44
Q

high concentration of Epi causes ____ of arterioles by stimulating ___ receptors

A

constriction ; alpha

45
Q

NE casues ____ of arterioles by stimulating ___ receptors

A

constriction; alpha

46
Q

in reflex regulation, the cerebral medulla is under influence of neuronal impulses from what 5 places?

A
  1. baroreceptors (arterial and cardiopulmonary)
  2. chemoreceptors (peripheral and central)
  3. hypothalamus that directly sense chemical
  4. cerebral cortex (emotional reflexs)
  5. skin (responds to pressure)
47
Q

reflex regulation is also affected by blood concentrations of ___ and __

A

CO2 and O2

48
Q

____ of peripheral vessels allowsdirection of blood flow to areas with greatest need

A

dual control

49
Q

in the brain and heart is intrinsic or extrinsic dominant? why?

A

intrinsic; vital structures with limited tolerance for reduced blood flow

50
Q

in the skin is intrinsic or extrinsic dominant? why?

A

extrinsic; important to homeostasis

51
Q

in skeletal muscle is intrinsic or extrinsic dominant? why?

A

both interact allowing for tuned response to large changes in metabolic activity

52
Q

when resting, skeletal muscle is mostly using ___ mechanisms, but with the onset of exercise, ___ mechanisms take over

A

extrinsic; intrinsic

53
Q

neural regulation of the vascular system is primarily done by what branch of the NS?

A

sympathetic nervous system

54
Q

autoregulation is mediated by a ____ mechanism whereby an increases in _____ induces vasoconstriction

A

myogenic; transmural pressure

55
Q

____ are the smallest blood vessels in the body, composed of only 1 endothelial layer thick

A

capillaries

56
Q

capillaries allow for the exchange of ___, ___ and ___ with interstitial fluid

A

gases, water , solutes

57
Q

blood flow in the capillaries depends on the contractile state of the ____, which can constrict to the point of stoppinf flow completely

A

arterioles

58
Q

capillaries have a large ___ and a ___ velocity

A

cross-sectional area; slow

59
Q

capillary exchange of solutes occurs in what 3 ways?

A
  1. diffusion
  2. filtration
  3. pinocytosis
60
Q

the rate of diffusion of water across capillary walls is ~40 x greater than the rate at which water is brought to the capillaries by __

A

blood flow

61
Q

diffusion of ____ molecules such as O2 and Co2 occurs directly through the lipid membrane

A

lipid-soluble

62
Q

diffusion of ___ molecules occurs through water filled pores in the membrane of the capillary

A

lipid-insoluble

63
Q

filtration at capillaries typically occurs through ____ and water movemnet is determined by balance of ___ across capillary wall

A

pores; starling forces

64
Q

____ in capillary is the principal force of filtration

A

hydrostatic pressure

65
Q

hydrostatic pressure (Pc) depends on what 2 things?

A
  1. arterial (upstream) and venous (downstream) pressures

2. resistance of arterioles and venules

66
Q

increases arterial / venous pressure results in ___ hydrostatic pressure

A

increased

67
Q

increased arteiole resistance results in ___ hydrostatic pressure

A

decreased

68
Q

increased venule pressure results in ____ hydrostatic pressure

A

increased

69
Q

what force opposes Pc?

A

hydrostatic pressure of interstitial fluid Pif

70
Q

osmotic pressure in the plasma of the capillary is called __ pressure

A

oncotic

71
Q

___ is the principle force of absorption (fluid movement) into the capillary

A

oncotic pressure

72
Q

oncotic pressure is generated by ___ due their inabilty to cross memnranes

A

plasma proteins (such as albumin)

73
Q

oncotic pressure is a key factor in preventing __

A

fluid loss from capillary

74
Q

oncotic pressure is opposed by what force?

A

osmotic pressure of interstitial fluid

75
Q

small amount of movement of ____ occurs through tiny pinocytotic vesicles formed by pinching off endothelial cell membrane

A

large lipid insoluble molecules

76
Q

the venous system returns blood to the heart from the tissue by ___

A

venous return

77
Q

the large resevoir of the venous system is due to ____ and contains ___% of the blood volume

A

high compliance; 70

78
Q

volume changes in the venous system results in ___ changes

A

pressure

79
Q

the venous system regulates flow of blood back to the heart by adjusting ____. This is called ___

A

stiffness; venomotor tone

80
Q

venous pressure is ____ by an increase in venomotor tone (constriction) with sympathetic sympathetic stimulation of smooth muscle

A

increased

81
Q

unlike with arterioles, constriction of veins ____ flow

A

increases

82
Q

venous pressure and venous return are ____ by skeletal muscle pump and respiratory pump

A

increased

83
Q

____ Is the driving pressure for venous return difference between peripheral venous pressure and right atrial pressure

A

venous pressure and flow

84
Q

explain the process of the skeletal muscle pump

A

muscle contraction compresses veins, forcing blood toward the heart as backward flow is prevented by one-way venous valves

85
Q

explain the process of the respiratory pump

A

during inspiration, intra-thoracic pressure is decreased while intra-abdominal pressure increased, increasing pressure difference between peripheral veins and the heart (and thus venous return)

86
Q

what happens to lymph vessels when muscle contraction

A

muscle contraction pulls on lymph vessels to open spaces between endothelial cells and permit proteins and large proteins and large particles into system

87
Q

t/f flow of lymph occurs by pressure, muscle/lymphatic contraction and one-way valves

A

true

88
Q

the lymphatic system is important for return of ___ and removal of ___

A

proteins; foreign particles (like bacteria)

89
Q

when the lymphatic system is overwhelmed / blocked, ___occurs

A

edema