KIN 321 Exam 2

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223 Terms

1
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What is vascular smooth muscle designed to do
regulate blood flow to active tissue
maintain systemic blood pressure
2
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What are the two primary sources of fluid loss?
urine
Sweat
3
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High intensity exercise produces enough heat to raise body temperature \_____ every \______ minutes. within 20 minutes it is life threatening and 40 minutes fatal
1 degree celsius
4-5
4
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A majority of the produced heat is transferred where via what
core, venous blood
5
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Greater than what % BW lost from dehydration is considered extremely dangerous?
7%+
6
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When the ambient temperature is higher than the skin, what are some unique sources of heat gain
Radiation
convection
conduction
(If the skin was hotter than environment these would contribute to heat loss)
7
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Core temperature is about \_____ degrees celsius
37
8
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Slight Dehydration can
significantly decrease VO2max and overall aerobic performance
9
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Is thirst a reliable sign of fluid need
NO IT IS NOT
10
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Dehydration is defined as
percentage loss of body weight
11
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Signs of acclimatization
decreased HR
ncreased Sweat rate
12
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When should heat acclimatization occur
1-2 months precomp
13
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most adaptations occur within
1-2 weeks
14
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What ambvient temperatures will be ideal for acclimatization
38.5
15
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Heat will move down a gradient via
radiation
conduction
convection
16
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Allcimatizstion to exercise in the heat will
increase plasma volume
17
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Sweat becomes \____ with acclimatization
diluted to preserve elecgtrolytes
18
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You start sweating earlier or later when acclimatized
earlier
19
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What are the two competing demands on the CVsystem during exercise
o2 and nutrient delivery

heat delivery to the periphrey for cooling
20
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Sweat is largely derived from
PLASMA
21
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What happens to venous return during exercise in the heat
increased HR to maintain cardiac output
22
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What happens to plasma volume during exercise in the heat
decreases--\> high blood pressure and sweat loss
23
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As exercise intensity increases past 60W
heat production surpasses heat lost
24
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The hypothalamus acts as the
thermostat
Heatloss--\> vasodilation
Heat conservation--\> vasoconstriction +shivering
25
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With exercise what is the gold standard
rectal
26
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Which method is relied on more heavily as ambient temperature increases
evaporation
27
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What is counterproductive sweating
water loss without cooling in hot, humid environment
28
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Evaporation is heavily influenced by
relative humidity (dryer the air the easier the sweat)
29
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What is the major mechanism of heat loss
the EVAPORATION of sweat off the skin (NOT WIPING IT OFF)
30
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Radiation accounts for \______ loss of heat in a neutral environment at rest
60%
31
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What improves the effectiveness of convection
movement of water or air across skin
32
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When the ambient temperature is higher than skin temperature how is heat lost
solely evaporation
33
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When the ambient temperature is less than skin temperature
Heat is lost through evaporation, radiation, conduction and convection
34
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What is heat exhaustion characterized by
rapid/weak pulse
hypotension (fluid loss and vasodilation to skin and muscle)
faintness
profuse sweating
35
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How is heat exhaustion treated?
Fluid replacement and cool environment
36
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What is heat syncope?
loss of consciousness with cessation of exercise in the heat (independent or secondary to heat exhaustion)
37
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What is heat stroke?
failure of the hypothalamic temp regulation--\> decreased sweat rate--\>massive heat storage
38
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What is the mortality rate of heat stroke? Why is it so high?
20%+
Heart failure and cerebral edema
39
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What is exercise associated hyponatremia?
The dilution of plasma Na+ below 135mmol/L
40
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what are some symptoms of EAH
altered CNS function--\> weakness, dizziness, lethargy, vomiting, headache, seizure
41
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Is EAH more prevalent in competitive athletes vs recreational?
recreational
42
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What is the largest predisposing factor of EAH
substantial weight gain from fluids
43
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How is sweat rate calculated?
\[BW chane + (Fluid intake-excretion)]/time as a fraction of an hour
44
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What is the general recommendation for pre exercise hydration?
6mL H2O/kg BW every 2-3 hours in the days leading up to the event
45
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Pre event hydration guidelines
16-24 fluid ounces 2 hours before
12 ounces 15 min before
46
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Intraworkout hydration guidelines
8-12 ounces every 15 min during practice or event lasting longer than 1 hour
(can be 6-8% CHO solution w some electrolytes)
47
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What should be the target hydration after exercise
consume 1.5L for every Kg weight lost
48
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Vascular smooth muscle vs skeletal muscle fibers
Smaller not striated
contract more slowly
capable of maintaining vascular tone with little energy
49
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What are the three factors that control vascular smooth muscle
Local
Humoral
Neural
50
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Why is there always slight vasoconstriction?
To guarantee adequate blood pressure and flow
51
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What is rate of blood flow determined by?
Blood pressure
52
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What is total peripheral resistance
the resistance to flow in the circulation
53
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What is TPR equal to
BP\=Q * TPR
54
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Increased TPR leads to
hypertension
55
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When CO (Q) is constant (steady state, rest) blood flow (BP) is regulated by
changes in TPR via vasoconstriction or dilation
56
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What is Poiseuilles equation (describes flow in a tube)
Flow\= (Pressure of Blood leaving heart- Pressure at distant site)piR^4/8LV
57
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What effect will increasing the radius of a blood vessel have on blood flow?
Vasodilation--\>increase BF
58
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What effect will increasing the pressure difference have on blood flow
increased BF
59
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Length is
unchanged
60
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What effect will being well hydrated have on blood flow?
being well hydrated leads to an increase in blood flow due to a lower viscosity
61
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How do you accomplish a 10-15 fold increase in blood flow to active skeletal muscle during exercise?
Increase Cardiac Output
Vasodilation of active muscles
Maintain hydration status
62
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What are some local vasodilatory metabolites?
Increased H+ (dec. pH)
Inc. K+
Inc. Adenosine and Lactate
Inc. PCO2
63
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Blood flow varies to the \___ power of radius
4th power (small changes in radius lead to big changes in blood flow)
64
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A \____% reduction in radius will lead to a \_____% reduced flow
16/50
65
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During active exercise where does blood flow get restricted to in order to give the active muscles blood
The gut gets reduced BF
66
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What percentage of blood goes to muscles during exercise
80-85%
67
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During exercise you vasoconstrict \______ and vasodilate at \_______
gut, active muscle
68
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Local control is only
vasodilatory
69
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What provides the signal to link local metabolism to blood flow?
sympathetic innervation @ adrenal medulla
70
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Blood flow increases exponentially with
increased rate of metabolism
71
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Vasodilators
increased
adenosine, lactate, hydrogen ion, potassium, PCO2
Decreased
PO2
72
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Endothelium likely potentiates local vasodilation via the release of
Nitric Oxide
73
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What causes NO release
shear stress
Response to CATS
74
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What increases NO secretion
endurance training
75
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Reactive hyperemia is an example of
local vasodilation
76
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Reduced blood flow through the kidney leads to the secretion of what
renin
77
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What is the function of renin
splits angiotensinogen from the liver to produce angiotensin I
78
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What is the function of ACE (angiotensin converting enzymes)
from the lungs
converts angiotensin I into Angiotensin II and III
79
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What is angiotensin II
a potent vasoconstrictor
80
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What hormone is secreted by the adrenal cortex in response to Angiotensin II
aldosterone\---\> increased water retention by the kidneys
81
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Overall dehydration leads to
increased blood pressure (this same effect from the renin angiotensin system can result from huge loss of blood)
82
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Humoral control of blood flow results in
both vasodilation and constriction
83
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Neural control is almost exclusively
vasoconstrictor
84
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Do sympathetic nerve fibers innervate capillaries
NO (they innervate all other blood vessels)
85
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Neural control results in
large unrefined changes
86
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Two medications that are vasodilators
ACE inhibitors
ARB (angiotensin receptor blocker\---\> blocks AII receptor)
87
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What parts of the body are most heavily innervated ? (blood vessel wise)
Kidney, gut, spleen
88
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What parts of the body are least innervated ?( blood vessel wise)
muscle, heart and brain
89
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Neural pushes blood flow to skeletal muscle generally, what pushes it to the active site
local control
90
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Does neural control distinguish between active/inactive skeletal muscle
No it does not
91
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Spinal cord injury may result in
lack of neural control so BP drops during exercise due to local vasodilation without compensatory vasoconstriction from neural
92
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The left ventricle gets blood from
left coronary artery
93
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The right ventricle gets blood from
right artery
94
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Myocardial BF may increase \______ from rest to max exercise because of
3x bc of a 5-20% NO primarily, secondarily from humoral/neural
95
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Diastolic BP should stay same or
decrease during exercise
96
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Ultimate goal of neural regulation of heart is
to maintain arterial blood pressure
97
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The \______ nervous system has primary neural control of the cardiac function
autonomic (heart is innervated by both sympathetic and parasympathetic)
98
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Sympathetic vasoconstriction (low-level input from vasoconstrictor area) is partially responsible for
resting BP
99
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Which division of the autonomic nervous system innervates the SA and AV node and atria (usually lowers the HR by inihibiting SA node)
Parasympathetic NS (dominant at rest)
100
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Which division of the autonomic system innervates the SA AV and ventricular myocardium (increase HR and SV)
Sympathetic NS