Regulation of Regional Circulation Flashcards
1
Q
What tissue has the most mass?
A
muscle
2
Q
What tissue has the most blood flow?
A
liver! (it loves blood) Kidney is second place, Brain is third
3
Q
What tissue has the most blood flow per mass?
A
KIDNEYS!!!!
4
Q
At rest, (blank) receive about 50% of total cardiac output.
A
Liver and kidneys
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
6
Q
Organs that exhibit pressure to flow autoregulation are (blank)
A
heart, brain and kidney.
7
Q
Blood flow to an organ remains (blank) over a wide range of perfusion pressures.
A
constant
8
Q
Put these in order of sympatetic innervation from greatest to least:
Brain, Kidney, muscle, skin
A
skin-> muscle-> kidney->brain and coronary
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)
10
Q
What are these: Histamine Bradykinin Serotonin (5-HT) Angiotensin II Endothelins Natriuretic peptides Nitric oxide *Adenosine *K+ *CO2
A
vasoactive substances
11
Q
Each tissue has its own (blank) calling for specialized vascular control
A
specialized functions
12
Q
Specialized functions of the brain are that it (blank) and (blank)
A
Requires uninterrupted blood supply
Increase local perfusion to local activity
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
14
Q
If you have decrease in norepinephrine what will happen to your blood vessel? increase in norepinephrine?
A
vasodilation
vasoconstriciton
15
Q
What are the two important structural adaptations o the brain>
A
circle of Willis
High capillary density
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)
17
Q
What is hypercapnia?
A
high CO2
18
Q
The most important local vasodilator for cerebral circulation is
A
CO2.
19
Q
Cerebral circulation has well-developed pressure/flow autoregulation, but (blank) overrides autoregulation.
A
hypercapnia
20
Q
What overrides autoregulation?
A
hypercapnia
21
Q
In the brain, hypercapnia causes (blank)
A
vasodilation
22
Q
In the brain, hypocapnia (low CO2) causes (blank)
A
vasoconstriction
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
24
Q
The (blank) of blood flow changes in characteristic ways with the other seven forms of cerebral activity.
A
pattern
25
The higher the activity, the more (blank)
blood flow
26
If you have increased cranial pressure what will this cause?
reduced cerebral blood flow and ischemia due to squishing of brain cells
27
What does ischemia tell the brain?
to stimulate vasomotor center to constrict peripheral blood flow and increase arterial pressure to resture cerebral blood flow
28
When is associatd with increased cranial pressure?
bradicardia due to compression-induced activation of the cardioinhibitory center.
29
What is the cushing reflex?
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
30
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.
sympathetic and parasympathetic
31
The Cushing reflex also comes into play after severe (blank) and (blank).
hypotension and circulatory shock
32
The primary function of the cerebral circulation is to ensure an uninterrupted supply of (blank) to the brain.
O2
33
cerebral circulation is controlled almost entirely by (blank)
local metabolic factors
34
(blank) is the MOST important vasodilator.
CO2
35
Sympathetic nerves play a (blank) role in cerebral circulation
minor
36
Cerebral circulation features highly restrictive nature of (blank)
cerebral capillaries (BBB)
37
Cerebreal circulation has what kind of pressure flow?
well developed pressure flow autoregulation
38
(blank) exhibits active and reactive hyperemia
cerebral circulation
39
What are the specialized functions of the heart?
Works 24 h
| Demands high energy and O2 to preform all this work
40
Cornoary flow is regulated in large part through changes in (blank)
coronary vascular resistance
41
Does the heart have weak or strong neural control?
weak (a1 vasoconstriction, b2 vasodilatation)
42
When you think of adenosine what organ do you think of it effecting?
heart
43
What factors are the most important function adaptions for the heart?
Metabolic intrinsic factors (direct correlation between coronary blood flow and work of the heart = active hyperemia).
44
What are the most important local metabolites in the coronary circulation?
hypoxia, adenosine, acidosis, hyperkalemia, and nitric oxide.
45
What are the four functional adaptations of the heart?
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)
46
What are the two structural adaptations of the heart?
Every muscle fiber has at least one supplying capillary
| - Maximum diffusion distance about 10 mm.
47
What are the five special challenges of the heart?
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
48
Why is the fact that coronoary arteries, end arteries a challenge in the heart?
sudden occlusion of one artery will cause ischemia or infarction
49
Why is the fact that cardiac hypertrophy a special challenge of the heart?
The diameter of fibers increases, but may not be accompanied by increased vascularization; Enlarged hearts are more vulnerable to circulatory insufficiency
50
What is coronary steal?
Coronary steal is when one region of the heart steals blood flow from another region so the other region becomes ischemic
51
What part of the heart is most susceptible to ischemic injury?
endocardium
52
Where is compression the greatest in the heart?
endocardium
53
The coronary circulation must deliver (blank) at a rate that keeps pace with cardiac demand
O2
54
Coronary circulation is controlled almost entirely by (blank)
intrinsic factors
55
What are the most important vasodilators of the coronary circulation?
adenosine, lactate, K+, and NO
56
(blank) exert only a small direct influence on the coronary blood flow (low density of receptors)
hormones and neurotransmitters
57
Every coronary(relating to or denoting the arteries that surround and supply the heart) muscle fiber has at least one (blank)
capillary
58
(blank) has excellent pressure flow autoregulation.
Coronary circulation
59
(blank) exhibits active and reactive (brisk) hyperemia
coronary circulation
60
In coronary circulation, the moment-to-moment flow of blood is strongly influenced by the (blank) activity of the heart
mechanical
61
The coronary vasculature in the normal heart has a great capacity to (blank) resistance (increase flow) in response to exercise.
decrease
62
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.
coronary reserve is already used up.
63
What are the two specialized functions of skeletal muscle?
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
What are the functional adaptations of skeletal muscle?
- 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
In skeletal muscle, At rest you have (blank) control
| During exercise you have (blank) control
systemic/ extrinsic control
| local/intrinsic control
66
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
Slow twitch- Type I red
67
What kind of muscle fibers are these:
| -sprinters
Fast twitch Type II
68
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.
active
69
(blank) dominates at rest due to persistent sympathetic activation.
Vasoconstriction
70
During exercise (blank) increases muscle blood flow by a) metabolic vasodilatation and capillary recruitment, and b) the skeletal muscle pump
vasodilatation
71
During exercise, vasoconstrictor sympathetic nerve activity generally (blank) even to exercising skeletal muscles.
increases,
72
How can the increased oxygen and nutritional demands of the exercising muscle be met?
due to metabolic vasodilation
73
The major mechanism by which blood flow increases during exercise is vasodilatation caused by (blank)
ischemic metabolites (K+, decreased pO2, adenosine, hypermolarity)
74
(blank) shortens the distance for nutrients to travel and improves energy delivery and waste removal.
Capillary recruitment
75
(blank) of terminal arterioles are not open at rest,
2/3
76
What is this called:
| 2/3 of terminal arterioles are not open at rest, but during exercise more capillaries are open.
capillary recruitment
77
Emptying of muscle veins lowers (blank) and helps drive arterial blood into skeletal muscle.
intramuscular venous pressure
78
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.
capacitance vessels back to the heart.
| intramuscular venous pressure
79
The muscle begins to contract rhythmically approximately once every (blank)
13 s
80
The muscle begins to contract rhythmically approximately once every 13 seconds. This causes an increase in mean blood flow because of (blank)
active hyperemia
81
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).
inhibits
82
Inhibited muscle blood flow caused by strong muscle contractions may pose quite a limitation during (blank)
isometric exercise.
83
Intravascular pressures are increased in exercising muscle, leading to increased capillary filtration. This may lead to (blank) in exercising muscle.
edema
84
Skeletal muscle circulation is controlled by both (blank) sympathetic innervation and (blank)
extrinsic
| local metabolic factors
85
What is the primary regulator of blood flow to the skeletal muscle at rest and what is vasoconstriction mediated by?
sympathetic nervous system (a1 constrction, b2 dilation)
| persisted activation of the SNS
86
In skeletal muscle circulation, During exercise, when O2 demand is high, the (blank) are dominant
local metabolic mechanisms
87
In skeletal muscle circulation, primary vasodilator substances are (blank)
lactate, adenosine and K+
88
Skeletal muscle circulation exhibits (blank) hyperemia.
active and reactive hyperemia (mechanical compression)
89
What are the two specialized functions of the skin?
1) Regulation of internal temperature (especially during exercise!)
2) Protection/response to injury
90
What are the functional adaptations of the skin?
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
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
core
| skin
92
What are the structural adaptations of the skin?
Extensive sympathetic innervation
Arteriovenous anastomoses (AVAs)
Large venous plexus (blood depot)
93
What are the special challenges of the skin?
Strenuous exercise in hot weather
| Hemorrhage; the role of skin blood flow in supporting blood pressure and preload
94
What do ateriovenous anastomoses do?
bypass capillaries
95
When it is cold outside, is sympathetic tone to AVAs high or low?
High!
96
(blank) are heavily innervated by sympathetic nerves.
AVAs
97
AV anastomoses (blank) in response to sympathetic stimulation.
close
98
The smooth muscle sphincters of these A-V shunts are controlled by temperature: cold = (blank) , heat = (blank).
vasoconstriction
| vasodilation
99
In nonapical skin regions do you have AVA's?
no
100
The nonapical skin lacks (blank) bodies
glomus
101
THe density of glomus bodies (AVA) is around 500cm^2 in the (blank)
nail beds
102
Bradykinin (blank) muscles
relaxes
103
if we get vasoconstriction in the cold why do we get red noses in the cold?
Paradoxical cold vasodilation due to paralysis of sympathetic neurotransmission to prevent skind damage due to prolonged exposure
104
Ambient temperate evokes a (blank) reflex
weak spinal
105
(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).
Anterior hypothalamus
106
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.
low
107
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).
rises
108
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.
hemorrhagic shock
109
Under extreme conditions, such as during hemorrhagic shock, skin blood flow participates in (blank) .
blood pressure maintenance
110
(blank) is the First sign of serious heat illness. Symptoms are cramps and confusion. Treatment: Rest in cool area, drink cool fluids, massage cramps.
heat stress
111
(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.
heat exhaustion
112
(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.
heat stroke
113
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
special challenges in hot weather strenous exercise
114
Mechanical damage, thermal injury, bug bites, etc. change (blank).
cutaneous flow
115
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.
triple response
| edema
116
(blank) controls (and is controlled by) temperature
cutaneous circulation
117
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)
vasodilation
118
Cutaneous circulation is controlled by (blank) (NE – vasculature - a1-adrenoceptors – vasoconstriction; SNS - ACh – sweat glands - release of bradykinin - vasodilation)
sympathetic nervous system
119
metabolic control is not important in (blank)
cutaneous circulation
120
paracrine control (axon reflex) is important in response to injury for (blank)
cutaneous circulation
121
Neurovascular response conducted through the C nociceptive nerve fibers is an Important mechanism for regulating the (blank).
microcirculation
122
What is the axon reflex?
Hypothetical pathway involved in the flare response
123
A bug bite or injury to the skin will cause (blank) to the local vessels?
vasodilation
