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Human physiology > Chapter 15: Blood Flow and the Control of Blood Pressure > Flashcards

Chapter 15: Blood Flow and the Control of Blood Pressure Flashcards

1
Q

closed system

A

circulatory system

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2
Q

force exerted by blood

A

pressure

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3
Q

which direction does flow occur?

A

from high pressure to low pressure

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4
Q

Blood flow to the organs and blood pressure are regulated by ……?

A
  • intrinsic controls

- extrinsic controls

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5
Q

flow =

A

=ΔP/R

=cardiac output (CO)

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6
Q

ΔP =

A

mean arterial pressure (MAP)

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7
Q

R=

A

total peripheral resistance (TPR)

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8
Q

CO=

A

MAP/TPR

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9
Q
  • take blood away from the heart
  • Elastic walls and thick layers of vascular smooth muscles
  • act as a pressure reservoir
A

arteries

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10
Q
  • take blood back to the heart
  • thin walls of vascular smooth muscles
  • act as volume reservoir
  • valves allow unidirectional blood flow (present in peripheral veins)
A

veins

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11
Q

site of variable resistance

A

arterioles

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12
Q

exchange between the blood and cells

A

capillaries

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13
Q

serve as an expandable volume reservoir

A

systemic veins

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14
Q

functions as an independent pump

A

each side of the heart

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15
Q

a pressure reservoir that maintains blood flow during ventricular relaxation

A

elastic systemic arteries

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16
Q

facilitates exchange

A

Absence of vascular smooth muscle and elastic tissue reinforcement in capillaries

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17
Q

what do capillaries have that help with exchange?

A

one cell-thick layer of endothelial cells on basal lamina

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18
Q

Contract and relax in response to local factors

A

precapillary sphincters

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19
Q
  • Intermediate between arterioles and capillaries

- Function as shunts to bypass capillaries

A

Metarterioles

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20
Q

what happens when precapillary sphincters are relaxed?

A

blood flows through all capillaries in the bed

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21
Q

what happens if precapillary sphincters constrict?

A

blood flow bypasses capillaries completely and flows through metarterioles

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22
Q
  • Storage site for pressure
  • Thick, elastic arterial walls
  • Low compliance
  • Expand as blood enters arteries during systole
  • Recoil during diastole
A

arteries as a pressure reservoir

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23
Q

is the ease with which a hollow vessel expands

A

compliance

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24
Q
  • in arteries

- Small increase in blood volume causes a large increase in pressure (balloon requires greater effort to inflate)

A

low compliance

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25
Q

Large increase in blood volume is required to produce a large increase in pressure (balloon expands easily)

A

high compliance

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26
Q

pushes blood into elastic arteries, causing them to stretch

A

ventricular contraction

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27
Q

what are the steps of ventricular contraction?

A
  1. ventricle contracts
  2. semilunar valve opens; blood ejected from ventricles flows into the arteries
  3. aorta and arteries expand and store pressure in elastic walls
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28
Q

how can blood pressure be measured?

A
  • pressure cuff and sphygmomanometer

- uncompressed artery

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29
Q
  • Compressed artery
  • Turbulent flow produces -Korotkoff sound
  • Pressure at first Korotkoff sound = systolic blood pressure
A

pressure cuff and sphygmomanometer

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30
Q
  • flow, no sound

- Pressure when sound disappears = diastolic blood pressure

A

uncompressed artery

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31
Q

when can the first Korotkoff sounds be heard?

A
  • created by pulsatile blood flow through the compressed artery
  • cuff pressure between 80 and 120 mmHG
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32
Q

when is the blood flow silent?

A
  • artery no longer compressed

- cuff pressure <80 mmHg

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33
Q

what is the measured BP shown as?

A

systolic pressure/diastolic pressure

-example 120/80

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34
Q

SP-DP=

A

pulse pressure

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35
Q

= diastolic P + 1/3(systolic P – diastolic P)

A

mean arterial pressure (MAP)

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36
Q

aortic pressure is closer to the minimum pressure twice as long

A

weighted mean

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37
Q

determines the mean arterial pressure

A

cardiac output and peripheral resistance

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38
Q

mean arterial pressure is directly proportional to…..?

A

cardiac output x resistance of arterioles

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39
Q

what are some factors that affect mean arterial pressure?

A
  • blood volume
  • effectiveness of the heart as a pump (cardiac output)
  • resistance of the system to blood flow
  • relative distribution of blood between arterial and venous blood vessels
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40
Q
  • resistant vessels
  • part of microcirculation
  • connect arteries to capillaries or metarterioles
  • Contain rings of smooth muscle to regulate radius and, therefore, resistance
A

arterioles

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41
Q
  • provide greatest resistance to blood flow
  • greater than 60% of TPR
  • resistance is regulated
  • largest pressure drop in vasculature
A

arterioles

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42
Q

alter the contractile state of arteriolar smooth muscle

A

intrinsic and extrinsic control mechanisms

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43
Q
  • include local metabolites

- controlling blood flow to individual capillary beds

A

intrinsic controls

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44
Q
  • control both ANS and hormones

- regulating mean arterial pressure

A

extrinsic controls

45
Q

causes vasoconstriction

A

contraction of smooth muscle (arterioles)

46
Q

causes vasodilation

A

relaxation of smooth muscle (arterioles)

47
Q

what is regulation of blood flow to organs based on?

A

based on need

48
Q

how is blood flow to organs regulated?

A

-by varying resistance

organ blood flow=MAP/organ resistance

49
Q

what is the Vascular smooth muscle response to four factors:

A
  1. metabolic activity
  2. changes in blood flow
  3. stretch of arteriolar smooth muscle
  4. local chemical messengers
50
Q

what do changes associated with increased metabolic activity cause?

A

vasodilation

51
Q

what do changes associated with decreased metabolic activity cause?

A

vasoconstriction

52
Q

increased blood flow in response to increased metabolic activity

A

active hyperemia

53
Q
  • O2 is delivered as fast as it is consumed

- CO2 is removed as fast as it is produced

A

steady state

54
Q
  • O2 is consumed faster than it is delivered

- CO2 is produced faster than it is removed

A

increased metabolic rate (active hyperemia)

55
Q

act on arteriolar

smooth muscle to promote vasodilation

A

The decreased oxygen concentration and increased

carbon dioxide concentration

56
Q

promotes increased blood flow, which
increases oxygen delivery to cells and carbon dioxide
removal from cells

A

vasodilation

57
Q

matches blood flow to increased metabolism

A

active hyperemia

58
Q

increased blood flow in response to a previous reduction in blood flow

A

reactive hyperemia

59
Q
  • Metabolites increase and oxygen decreases

- Vasodilation

A

blockage of blood flow to tissues (reactive hyperemia)

60
Q
  • Increased blood flow due to low resistance

- Metabolites removed, oxygen delivered

A

occurs when blockage is released (reactive hyperemia)

61
Q

follows a period of decreased blood flow

A

reactive hyperemia

62
Q

change in vascular resistance in response to stretch of blood vessels in the absence of external factors

A

myogenic response

63
Q
  • Increased pressure in arteriole stretches arteriole wall
  • Stretch of vascular smooth muscle induces contraction of vascular smooth muscle—inherent property of smooth muscle
  • Vasoconstriction decreases blood flow
  • Purpose: keep blood flow constant (autoregulate)
A

myogenic autoregulation

64
Q

happens because of changes in perfusion pressure

A

myogenic response

65
Q

depends on total peripheral resistance (TPR)

A

mean arterial pressure

66
Q

depends on radius of arterioles

A

total peripheral resistance (TPR)

67
Q
  • regulated by extrinsic mechanisms to control mean arterial pressure
    • sympathetic activity
    • hormones
A

radius of arterioles

68
Q
  • Sympathetic innervation of smooth muscle of arterioles
  • Norepinephrine binds to α adrenergic receptors
  • Produces vasoconstriction
  • Increases TPR
  • Increases MAP
A

Sympathetic control of arteriolar radius

69
Q

controlled by tonic release of norepinephrine

A

arteriole diameter

70
Q

as signal rate increases…..?

A

the blood vessels constricts

71
Q

as the signal rate decreases…..?

A

the blood vessel dilates

72
Q

what hormones are involved in hormone control?

A
  • epinephrine
  • vasopressin (ADH)
  • angiotensin II
73
Q

released from adrenal medulla

A

epinephrine

74
Q
  • Secreted by posterior pituitary
  • Increases water reabsorption by kidneys
  • Vasoconstriction
A

vasopressin (ADH)

75
Q
  • Vasoconstriction

- Increases TPR

A

angiotensin II

76
Q

how is mean arterial pressure regulated?

A
  • neural control of MAP

- negative feedback loops

77
Q

baroreceptors

A

detector for negative feedback loops (of MAP)

78
Q

cardiovascular centers in the brainstem

A

integration center (of MAP)

79
Q

autonomic nervous system

A

controllers (of MAP)

80
Q

heart and blood vessels

A

effectors (of MAP)

81
Q
  • pressure receptors
  • sometimes called stretch receptors
  • Respond to stretching due to pressure changes in arteries
A

baroreceptors

82
Q
  • sinoaortic receptors
  • aortic arch
  • carotid sinuses
A

arterial baroreceptors

83
Q

exchange materials across thin capillary walls

A

plasma and cells

84
Q

related to metabolic activity of cells

A

capillary density

85
Q
  • have the thinnest walls
  • Single layer of flattened endothelial cells
  • Supported by basal lamina
A

capillaries

86
Q

what are the kinds of capillaries?

A
  • continuous

- fenestrated

87
Q

do not have typical capillaries but rather sinusoids

A

Bone marrow, liver, and spleen

88
Q

occurs by paracellular pathway or endothelial transport

A

Exchange between plasma and interstitial fluid

89
Q

move by diffusion, depending on lipid solubility and concentration gradient

A

small dissolved solutes and gases

90
Q

move mostly by vesicular transport

A

larger solutes and proteins

91
Q

transported by transcytosis

A

large molecules and selected proteins in most capillaries

92
Q
  • most common capillaries
  • small gaps between endothelial cells
    • allow small water soluble molecules to move through
A

continuous capillaries

93
Q
  • Large gaps between endothelial cells forming pores or fenestrations (windows)
  • Allow proteins, and in some cases blood cells, to move through
A

fenestrated capillaries

94
Q

have leaky junctions

A

continuous capillaries

95
Q

may fuse to create temporary channels

A

some vesicles

96
Q

have large pores

A

fenestrated capillaries

97
Q

Mass movement as a result of hydrostatic or osmotic pressure gradients

A

bulk flow

98
Q
  • fluid movement out of capillaries
  • caused by hydrostatic pressure
  • net filtration at arterial end
A

filtration

99
Q
  • fluid movement into capillaries
  • Net absorption at venous end
  • Caused by colloid osmotic pressure (due to proteins)
A

absorption

100
Q

forces fluid out of the capillary

A

hydrostatic pressure

101
Q

net pressure=

A

hydrostatic pressure-colloid osmotic pressure

102
Q

indicates filtration

A

positive net pressure

103
Q

indicates absorption

A

negative net pressure

104
Q

pulls fluid into the capillary

A

colloid osmotic pressure of proteins within the capillary

105
Q

what is the net average of fluid that filters out of the capillaries?

A

3L/day

106
Q

picked up by the lymph vessels and returned to the circulation

A

excess of water and solutes that filter out of the capillary

107
Q
  • Return fluid and proteins to circulatory system
  • Pick up fat absorbed and transferring it to circulatory system
  • Serve as filter for pathogens
A

lymphatic system

108
Q

what are the two main causes of edema?

A
  • Inadequate drainage of lymph

- Filtration far greater than absorption

109
Q
  • Increase in hydrostatic pressure
  • Decrease in plasma protein concentration
  • Increase in interstitial proteins
A

Filtration far greater than absorption

Human physiology (17 decks)

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