Midterm 1 - Blood Vessels and Blood Pressure Flashcards

1
Q

important factors of blood pressure in blood vessels

A

diameter
elasticity
contractility

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2
Q

what blood vessel is the target to regulate pressure

A

arteriole

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3
Q

how does an edema occur

A

no venous return, blood sits in capillaries and fluid builds

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4
Q

flow

A

volume of fluid transported per time unit

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5
Q

what is flow between 2 points dependent on

A

pressure difference between the 2 points and resistance to fluid

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6
Q

how to calculate flow (Q)

A

pressure difference/resistance

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7
Q

is pressure higher in arteries or veins

A

arteries

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8
Q

what are arterioles

A

the “bottlenecks” of the circulation

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9
Q

why are arterioles the main site of pressure/flow regulation

A

they have the most smooth muscle

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10
Q

what does initial pressure result from

A

heart contraction

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11
Q

does pressure progressively increase or decrease

A

decrease

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12
Q

what does resistance depend on

A

length of vessel
radius of vessel
blood viscosity

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13
Q

what is constant in an individual

A

the length of vessel

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14
Q

what is the most important factor for resistance

A

radius of vessel

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15
Q

why is radius so important for resistance

A

resistance decreases by the 4th power of the radius: if the radius increased 2 times, resistance decreases 16 times

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16
Q

what does viscosity of blood vary with

A

cells and proteins amount

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17
Q

what occurs during ventricular contraction when aortic valves open

A

rapid flow of blood
increased arterial pressure
some pressure is absorbed by aorta elasticity

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18
Q

what does aorta elasticity do with pressure

A

temporarily stores energy like a rubber plastic

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19
Q

what occurs during diastole when the aortic valve closes

A

no blood flowing from ventricle
stored energy is released
allows blood flow to continue in vessels
gradual decrease in arterial pressure

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20
Q

what are compliant

A

arteries

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21
Q

what does the elasticity and large diameter of arteries supply

A

low resistance
high flow

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22
Q

what does the recoil of wall of artery limit

A

the drop in pressure after systole

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23
Q

how can a difference in arterial blood pressure be observed

A

between systole pressure and diastole pressure

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24
Q

pulse pressure

A

difference between systolic and diastolic pressure

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25
Q

what occurs to the mean blood pressure during rest

A

MBP closer to diastolic pressure (diastolic lasts longer than systole)

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26
Q

what occurs to the mean blood pressure during exercise

A

MBP closer to systolic pressure (heart rate increased = diastole shortened)

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27
Q

what is pulse pressure the measure of

A

measure of pressure on artery wall during systole

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28
Q

factors influencing arterial pressure

A

elasticity of artery
cardiac output
respiration
resistance to blood flow
blood volume

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29
Q

what is the main factor influencing arterial pressure

A

resistance to blood flow

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30
Q

what influence does aging have with elasticity of artery

A

low elasticity = high pressure

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31
Q

what influence does more blood from systole have on pressure

A

more blood = increased pressure

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32
Q

what occurs during inspiration

A

low pressure in thoracic cavity, high pressure in abdominal cavity

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33
Q

what does the pressure occurring during inspiration promote

A

venous return

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34
Q

what does total peripheral resistance depend on

A

vasoconstriction of arterioles. increase in TPR = increase pressure

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35
Q

what does blood volume influence

A

cardiac output

36
Q

why does blood volume have minimal effect on cardiac output

A

vein absorb the major effect

37
Q

what is unique about arteriole walls

A

they have fewer elastic fibers but larger number of smooth muscle fibers

38
Q

what is the basal level of constriction

A

myogenic (basal) tone

39
Q

what does the myogenic tone make possible

A

to decrease and increase vessels contraction thus diameter

40
Q

what happens too resistance when diameter decreases

A

resistance increases

41
Q

what are the 2 levels of control of arteriolar resistance

A

autoregulation (local mechanisms)
extrinsic control factor (neuro-hormonal)

42
Q

what does auto regulation do within organ or tissue

A

overrides extrinsic regulation

43
Q

what does autoregulation control

A

flow to critical organs = protective mechanism

44
Q

types of autoregulation

A

metabolic regulation
myogenic (pressure) regulation

45
Q

what does metabolic regulation respond to

A

changes in metabolism, thus blood requirement

46
Q

what does metabolic regulation increase in

A

diameter (decrease in pH, increase in CO2, K+, NO)

47
Q

what does the relative importance of factors in metabolic regulation depend on

A

the organ

48
Q

what does myogenic auto regulation entail

A

vessels respond to changes in tone or stretch

49
Q

what does myogenic autoregutalion maintain

A

the blood supply is virtually unchanged even when pressure changes

50
Q

how does autoregulation adapt

A

locally with specific organs to maintain function

51
Q

when is extrinsic regulation activated

A

when there is a problem

52
Q

what does extrinsic regulation regulate

A

the peripheral pressure as a whole

53
Q

what are the vasoconstrictive influences of extrinsic regulation

A

sympathetic stimulation on a-adrenergic receptors
angiotensin II
arginin vasopressin

54
Q

what is a vasodilatory influence of extrinsic regulation

A

parasympathetic stimulation (vagus nerve, mainly penis and clitoris)

55
Q

how low can pressure be when blood enters venous system

A

10 mm Hg

56
Q

what does the heart act as

A

a pump

57
Q

what kind of muscles do veins possess

A

smooth

58
Q

what occurs when pressure in veins is too high

A

flow is reduced and fluid leaks out and accumulates in tissue - edema

59
Q

how can skeletal muscle activity help with veins and venous pressure

A

it can help squeeze blood upward

60
Q

what side of the heart has higher pressure

A

right

61
Q

what happens to pressure during inspiration

A

P in thoracic cavity decreases
P in abdonominal cavity increases

62
Q

main variables of controlling blood pressure

A

heart rate
stroke volume
TPR

63
Q

what contribute to blood pressure reflex

A

baroreceptors
sensory fibers
integration center
motor fibers
effectors

64
Q

what are baroreceptors

A

stretch receptors

65
Q

what do baroreceptors sense

A

stretching of arterial wall

66
Q

where are baroreceptors located

A

sensitive areas:
aortic arch
carotid sinus

67
Q

what do baroreceptors have

A

free nerve endings

68
Q

where do sensory fibers ascend

A

via vagus nerve

69
Q

what happens due to sensory fibers when stretch increases

A

increase in APs frequency

70
Q

what happens due to sensory fibers when stretch decreases

A

decrease in AP frequency

71
Q

what is the integration center

A

cardiovascular (vasomotor) center in the medulla oblongata

72
Q

what does the integration center do

A

compares info to reference value

73
Q

what are the effectors involved with controlling blood pressure

A

heart
arterioles and vein

74
Q

example of baroreceptors in action

A

postural hypotension

75
Q

what is postural hypotension

A

change from lying to standing position

76
Q

what does the atrial volume receptor reflex

A

stretch receptors in wall of atria and regulate blood volume

77
Q

how does the atrial volume receptor reflex regulate blood volume

A

via autonomic nervous system activity
neural input that controls this and the secretion of hormones that alter renal handling of sodium and water

78
Q

what are the stretch receptors in wall of atria

A

volume receptors

79
Q

what is atrial natriuretic peptide (ANP)

A

hormone synthesized in atrial wall

80
Q

what does ANP increase

A

sodium excretion

81
Q

what is renin

A

hormone synthesized in kidney which increases synthesis of angiotensin II to create aldosterone

82
Q

what are hormones involved in BP regulation

A

atrial natriuretic peptide
renin
antidiuretic hormone = vasopressin (post. pituitary)

83
Q

what does antidiuretic hormone vasopressin do

A

decrease water excretion in kidney - decrease water loss in urine

84
Q

what does angiotensin II do `

A

vasoconstriction

85
Q

what does aldosterone do

A

decrease sodium excretion

86
Q

what is vasoconstriction

A

when there is a drop in blood volume, decreases arterial going into kidney