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Block 2 Week 3 > Regulation of Regional Circulation > Flashcards

Regulation of Regional Circulation Flashcards

1
Q

What tissue has the most mass?

A

muscle

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2
Q

What tissue has the most blood flow?

A

liver! (it loves blood) Kidney is second place, Brain is third

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3
Q

What tissue has the most blood flow per mass?

A

KIDNEYS!!!!

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4
Q

At rest, (blank) receive about 50% of total cardiac output.

A

Liver and kidneys

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5
Q

The (blank) receives less than 5% of cardiac output, but accounts for more than 10% of total O2 consumption.

A

heart! it loves oxygen

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6
Q

Organs that exhibit pressure to flow autoregulation are (blank)

A

heart, brain and kidney.

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7
Q

Blood flow to an organ remains (blank) over a wide range of perfusion pressures.

A

constant

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8
Q

Put these in order of sympatetic innervation from greatest to least:
Brain, Kidney, muscle, skin

A

skin-> muscle-> kidney->brain and coronary

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9
Q

Vascular resistance increases a lot with activation of (blank) in the skin. Why dont you get increased resistance with brain and heart?

A

sympathetic innervation

presence of B2 receptors (vasodilators)

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10
Q 
What are these:
Histamine			Bradykinin
Serotonin (5-HT)		Angiotensin II
Endothelins		Natriuretic peptides
Nitric oxide		*Adenosine
*K+				*CO2
A

vasoactive substances

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11
Q

Each tissue has its own (blank) calling for specialized vascular control

A

specialized functions

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12
Q

Specialized functions of the brain are that it (blank) and (blank)

A

Requires uninterrupted blood supply

Increase local perfusion to local activity

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13
Q

What are the six functional adaptations of the brain?

A 
High basal flow
Protects its own supply
Autoregulation
Sensitivity to CO2 and hypoxia
Local metabolic hyperemia (active hyperemia)
BBB
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14
Q

If you have decrease in norepinephrine what will happen to your blood vessel? increase in norepinephrine?

A

vasodilation

vasoconstriciton

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15
Q

What are the two important structural adaptations o the brain>

A

circle of Willis

High capillary density

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16
Q

What are the 2 special challenges of the brain?

A

Effects of gravity (postural hypotension)

Occupies a ‘rigid box’ (no room to expand)

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17
Q

What is hypercapnia?

A

high CO2

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18
Q

The most important local vasodilator for cerebral circulation is

A

CO2.

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19
Q

Cerebral circulation has well-developed pressure/flow autoregulation, but (blank) overrides autoregulation.

A

hypercapnia

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20
Q

What overrides autoregulation?

A

hypercapnia

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21
Q

In the brain, hypercapnia causes (blank)

A

vasodilation

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22
Q

In the brain, hypocapnia (low CO2) causes (blank)

A

vasoconstriction

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23
Q

Why does hyperventiliation cause syncope?

A

your are getting rid of too much CO2 and low CO2 (hypocapnia) you get vasoconstriction; not enough blood flow to your brain

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24
Q

The (blank) of blood flow changes in characteristic ways with the other seven forms of cerebral activity.

A

pattern

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25
Q

The higher the activity, the more (blank)

A

blood flow

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26
Q

If you have increased cranial pressure what will this cause?

A

reduced cerebral blood flow and ischemia due to squishing of brain cells

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27
Q

What does ischemia tell the brain?

A

to stimulate vasomotor center to constrict peripheral blood flow and increase arterial pressure to resture cerebral blood flow

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28
Q

When is associatd with increased cranial pressure?

A

bradicardia due to compression-induced activation of the cardioinhibitory center.

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29
Q

What is the cushing reflex?

A

Increased cranial pressure leading to compression of cerebral arteries leading to decreased cerebral blood flow and ischemia which stimulate vasomotor center to constrict peripheral blood flow and increase arterial pressure to resture cerebral blood flow

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30
Q

A high intracranial pressure (pressure as high as 300 to 400 mm Hg) produces the Cushing reaction in which cardiovascular centers are stimulated, and both (blank) input to the cardiovascular system increase.

A

sympathetic and parasympathetic

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31
Q

The Cushing reflex also comes into play after severe (blank) and (blank).

A

hypotension and circulatory shock

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32
Q

The primary function of the cerebral circulation is to ensure an uninterrupted supply of (blank) to the brain.

A

O2

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33
Q

cerebral circulation is controlled almost entirely by (blank)

A

local metabolic factors

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34
Q

(blank) is the MOST important vasodilator.

A

CO2

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35
Q

Sympathetic nerves play a (blank) role in cerebral circulation

A

minor

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36
Q

Cerebral circulation features highly restrictive nature of (blank)

A

cerebral capillaries (BBB)

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37
Q

Cerebreal circulation has what kind of pressure flow?

A

well developed pressure flow autoregulation

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38
Q

(blank) exhibits active and reactive hyperemia

A

cerebral circulation

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39
Q

What are the specialized functions of the heart?

A

Works 24 h

Demands high energy and O2 to preform all this work

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40
Q

Cornoary flow is regulated in large part through changes in (blank)

A

coronary vascular resistance

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41
Q

Does the heart have weak or strong neural control?

A

weak (a1 vasoconstriction, b2 vasodilatation)

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42
Q

When you think of adenosine what organ do you think of it effecting?

A

heart

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43
Q

What factors are the most important function adaptions for the heart?

A

Metabolic intrinsic factors (direct correlation between coronary blood flow and work of the heart = active hyperemia).

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44
Q

What are the most important local metabolites in the coronary circulation?

A

hypoxia, adenosine, acidosis, hyperkalemia, and nitric oxide.

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45
Q

What are the four functional adaptations of the heart?

A

1) Coronary Flow->regulated by coronary vascular resistance
2) Weak neural control
3) Metabolic intrinsic factors
4) coronary reserve (flow increase 3-4 fold during exercise)

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46
Q

What are the two structural adaptations of the heart?

A

Every muscle fiber has at least one supplying capillary

- Maximum diffusion distance about 10 mm.

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47
Q

What are the five special challenges of the heart?

A

1) Coronary arteries are end arteries
2) cardiac hypertrophy
3) reactive hyperemia
4) supply: demand imbalance during tachycardia
5) coronary reserve and coronary steal during exercise in disease states

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48
Q

Why is the fact that coronoary arteries, end arteries a challenge in the heart?

A

sudden occlusion of one artery will cause ischemia or infarction

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49
Q

Why is the fact that cardiac hypertrophy a special challenge of the heart?

A

The diameter of fibers increases, but may not be accompanied by increased vascularization; Enlarged hearts are more vulnerable to circulatory insufficiency

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50
Q

What is coronary steal?

A

Coronary steal is when one region of the heart steals blood flow from another region so the other region becomes ischemic

51
Q

What part of the heart is most susceptible to ischemic injury?

A

endocardium

52
Q

Where is compression the greatest in the heart?

A

endocardium

53
Q

The coronary circulation must deliver (blank) at a rate that keeps pace with cardiac demand

A

O2

54
Q

Coronary circulation is controlled almost entirely by (blank)

A

intrinsic factors

55
Q

What are the most important vasodilators of the coronary circulation?

A

adenosine, lactate, K+, and NO

56
Q

(blank) exert only a small direct influence on the coronary blood flow (low density of receptors)

A

hormones and neurotransmitters

57
Q

Every coronary(relating to or denoting the arteries that surround and supply the heart) muscle fiber has at least one (blank)

A

capillary

58
Q

(blank) has excellent pressure flow autoregulation.

A

Coronary circulation

59
Q

(blank) exhibits active and reactive (brisk) hyperemia

A

coronary circulation

60
Q

In coronary circulation, the moment-to-moment flow of blood is strongly influenced by the (blank) activity of the heart

A

mechanical

61
Q

The coronary vasculature in the normal heart has a great capacity to (blank) resistance (increase flow) in response to exercise.

A

decrease

62
Q

In disease states, e.g., atherosclerosis, vessels may already be maximally dilated to ensure flow under resting conditions so how does this effect coronoary reserve.

A

coronary reserve is already used up.

63
Q

What are the two specialized functions of skeletal muscle?

A

Contributes to maintenance of blood pressure (significant amount of vascular tone at rest)
Oxygen/substrate delivery to exercising muscle (blood flow can increased up to 20 fold in exercising muscle)

64
Q

What are the functional adaptations of skeletal muscle?

A
  • slow twitch(marathoners type I)/fast twitch (sprinters type II) fibers
  • Different mechanisms control the circulation at the skeletal muscle at rest and during exercise
65
Q

In skeletal muscle, At rest you have (blank) control

During exercise you have (blank) control

A

systemic/ extrinsic control

local/intrinsic control

66
Q

What kind of muscle fibers are these:

  • high capillary density
  • high mitochondrial content
  • high myoglobin
  • muscles with almost constant metabolic demands (marathoners)
  • high metabolic demand
A

Slow twitch- Type I red

67
Q

What kind of muscle fibers are these:

-sprinters

A

Fast twitch Type II

68
Q

Tonically (blank), postural, muscles, have a high concentration of Type I fibers and increased capillary density, and are thus well-equipped to meet the almost constant metabolic demands due to increased mitochondrial density, increased myoglobin content, and increased capillary density.

A

active

69
Q

(blank) dominates at rest due to persistent sympathetic activation.

A

Vasoconstriction

70
Q

During exercise (blank) increases muscle blood flow by a) metabolic vasodilatation and capillary recruitment, and b) the skeletal muscle pump

A

vasodilatation

71
Q

During exercise, vasoconstrictor sympathetic nerve activity generally (blank) even to exercising skeletal muscles.

A

increases,

72
Q

How can the increased oxygen and nutritional demands of the exercising muscle be met?

A

due to metabolic vasodilation

73
Q

The major mechanism by which blood flow increases during exercise is vasodilatation caused by (blank)

A

ischemic metabolites (K+, decreased pO2, adenosine, hypermolarity)

74
Q

(blank) shortens the distance for nutrients to travel and improves energy delivery and waste removal.

A

Capillary recruitment

75
Q

(blank) of terminal arterioles are not open at rest,

A

2/3

76
Q

What is this called:

2/3 of terminal arterioles are not open at rest, but during exercise more capillaries are open.

A

capillary recruitment

77
Q

Emptying of muscle veins lowers (blank) and helps drive arterial blood into skeletal muscle.

A

intramuscular venous pressure

78
Q

Rhythmic muscle contraction during exercise expels the venous blood from the (blank).This emptying of muscle veins lowers (blank), and helps drive arterial blood into skeletal muscle.

A

capacitance vessels back to the heart.

intramuscular venous pressure

79
Q

The muscle begins to contract rhythmically approximately once every (blank)

A

13 s

80
Q

The muscle begins to contract rhythmically approximately once every 13 seconds. This causes an increase in mean blood flow because of (blank)

A

active hyperemia

81
Q

Each contraction of the skeletal muscle transiently (blank) its blood flow by mechanically compressing the blood vessels inside the muscle, but this is not a problem during rhythmic exercise (reactive hyperemia).

A

inhibits

82
Q

Inhibited muscle blood flow caused by strong muscle contractions may pose quite a limitation during (blank)

A

isometric exercise.

83
Q

Intravascular pressures are increased in exercising muscle, leading to increased capillary filtration. This may lead to (blank) in exercising muscle.

A

edema

84
Q

Skeletal muscle circulation is controlled by both (blank) sympathetic innervation and (blank)

A

extrinsic

local metabolic factors

85
Q

What is the primary regulator of blood flow to the skeletal muscle at rest and what is vasoconstriction mediated by?

A

sympathetic nervous system (a1 constrction, b2 dilation)

persisted activation of the SNS

86
Q

In skeletal muscle circulation, During exercise, when O2 demand is high, the (blank) are dominant

A

local metabolic mechanisms

87
Q

In skeletal muscle circulation, primary vasodilator substances are (blank)

A

lactate, adenosine and K+

88
Q

Skeletal muscle circulation exhibits (blank) hyperemia.

A

active and reactive hyperemia (mechanical compression)

89
Q

What are the two specialized functions of the skin?

A

1) Regulation of internal temperature (especially during exercise!)
2) Protection/response to injury

90
Q

What are the functional adaptations of the skin?

A

1) Cutaneous blood flow is under extrinsic control by sympathetic fibers (linked to body temp)
2) In apical skin (anything poking out) -> arteriovenous anastomoses
3) In nonapical skin (limbs head trunk)-> mediated by sympathetic nervous system and local effects of temperature

91
Q

In a cold day blood flow is mainly in the (blank).

In a hot day heat is lost at the (blank) due to increased blood flow in the skin

A

core

skin

92
Q

What are the structural adaptations of the skin?

A

Extensive sympathetic innervation
Arteriovenous anastomoses (AVAs)
Large venous plexus (blood depot)

93
Q

What are the special challenges of the skin?

A

Strenuous exercise in hot weather

Hemorrhage; the role of skin blood flow in supporting blood pressure and preload

94
Q

What do ateriovenous anastomoses do?

A

bypass capillaries

95
Q

When it is cold outside, is sympathetic tone to AVAs high or low?

A

High!

96
Q

(blank) are heavily innervated by sympathetic nerves.

A

AVAs

97
Q

AV anastomoses (blank) in response to sympathetic stimulation.

A

close

98
Q

The smooth muscle sphincters of these A-V shunts are controlled by temperature: cold = (blank) , heat = (blank).

A

vasoconstriction

vasodilation

99
Q

In nonapical skin regions do you have AVA’s?

A

no

100
Q

The nonapical skin lacks (blank) bodies

A

glomus

101
Q

THe density of glomus bodies (AVA) is around 500cm^2 in the (blank)

A

nail beds

102
Q

Bradykinin (blank) muscles

A

relaxes

103
Q

if we get vasoconstriction in the cold why do we get red noses in the cold?

A

Paradoxical cold vasodilation due to paralysis of sympathetic neurotransmission to prevent skind damage due to prolonged exposure

104
Q

Ambient temperate evokes a (blank) reflex

A

weak spinal

105
Q

(blank) senses core temperature and controls brainstem neurons, which govern sympathetic neural discharge to skin (SNS mediates vasoconstriction in acral skin and vasodilatation in non-acral skin – later responses).

A

Anterior hypothalamus

106
Q

When body core temperature is (blank), thermosensitive regions of the hypothalamus induce increased sympathetic activity to the fibers innervating the arterio-venous anastomoses and cause vasoconstriction.

A

low

107
Q

As core temperature (blank), so does skin temperature and flow. This is a withdrawal of sympathetic tone (in acral/apical skin) and vasodilation due to bradykinin release from sweat glands that are innervated by sympathetic fibers releasing ACh (in non-apical skin).

A

rises

108
Q

What happens if you have these symptoms:
Severe hypotension
Skin vasoconstriction
“Cold and Pale” appearance
Skin vasoconstriction supports blood pressure
Skin venoconstriction contributes to preload
During WWI “rescue” with warm blanket resulted in rapid death, compared to better survival in those difficult to reach but who retained their natural vasoconstriction.

A

hemorrhagic shock

109
Q

Under extreme conditions, such as during hemorrhagic shock, skin blood flow participates in (blank) .

A

blood pressure maintenance

110
Q

(blank) is the First sign of serious heat illness. Symptoms are cramps and confusion. Treatment: Rest in cool area, drink cool fluids, massage cramps.

A

heat stress

111
Q

(blank) is Caused by excessive loss of fluids, relative volume depletion. Core temperature is not elevated. Symptoms: Heavy sweating, paleness, muscle cramps, fatigue, faintness, dizziness, nausea, headaches, rapid breathing and pulse. Treatment: Rest in cool area, drink cool fluids, massage cramps.

A

heat exhaustion

112
Q

(blank) Develops in the setting of untreated heat exhaustion. Symptoms: Core temperature elevated, dry skin, loss of consciousness, seizures, rapid weak pulse, vomiting. Treatment: 911, Ice packs, oral or IV hydration.

A

heat stroke

113
Q

What are these problems for?
Mandates increased blood flow to working muscle and increased core temperature.
Decreases peripheral resistance.
Decreases plasma volume due to transcapillary filtration (relative volume depletion).

Capacity of heart to maintain cardiac output may be exceeded, leading to hypotension and collapse.
Heat stress, heat exhaustion, heat stroke

A

special challenges in hot weather strenous exercise

114
Q

Mechanical damage, thermal injury, bug bites, etc. change (blank).

A

cutaneous flow

115
Q

Trauma produces “ (blank)” in skin – a red line, a red flare, and a wheal. A wheal is local (blank) that results from the local release of histamine, which increases capillary filtration.

A

triple response

edema

116
Q

(blank) controls (and is controlled by) temperature

A

cutaneous circulation

117
Q

temperature regulation is the principal function of the cutaneous sympathetic nerves (cold causes vasoconstriction due to SNS stimulation; heat causes (blank) due to SNS withdrawal)

A

vasodilation

118
Q

Cutaneous circulation is controlled by (blank) (NE – vasculature - a1-adrenoceptors – vasoconstriction; SNS - ACh – sweat glands - release of bradykinin - vasodilation)

A

sympathetic nervous system

119
Q

metabolic control is not important in (blank)

A

cutaneous circulation

120
Q

paracrine control (axon reflex) is important in response to injury for (blank)

A

cutaneous circulation

121
Q

Neurovascular response conducted through the C nociceptive nerve fibers is an Important mechanism for regulating the (blank).

A

microcirculation

122
Q

What is the axon reflex?

A

Hypothetical pathway involved in the flare response

123
Q

A bug bite or injury to the skin will cause (blank) to the local vessels?

A

vasodilation

Block 2 Week 3 (9 decks)

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