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KNES 373 > CV physiology II > Flashcards

CV physiology II Flashcards

1
Q

what is the arteries function

A

establish bulk flow and driving pressure
(doesn’t care where the blood goes)

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2
Q

what is the arterioles function

A

regulate blood flow
distribute blood to different regions

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3
Q

what is the function of capillaries

A

sites for gas exchange with tissues

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4
Q

what is the function of veins / venules

A

regulate flow return

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5
Q

how does a-VO2 difference change with intensity

A

widens the a-VO2 difference as intensity increases

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6
Q

how does arterial O2 content change as exercise intensity increases

A

stays constant
- increased ventilation ensures nearly complete arterial saturation

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7
Q

how does venous O2 content change as exercise intensity increases

A

declines
- more O2 taken up by muscles

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8
Q

what determines HR

A

tradeoff between vagal tone and sympathetic activation

vagal tone = high at rest, low during exercise
sympathetic activation = high during exercise

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9
Q

what is SV

A

difference in ventricular volume at the end of diastole and end of systole
mL/beat
SV = EDV - ESV

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10
Q

what is ejection fraction

A

fraction (%) of blood pumped out of LV relative to total volume of LV
EF = SV / EDV

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11
Q

what is the difference in SV and EDV in trained individuals

A

SV and EDV higher in trained
- bigger and stronger heart

ejection fraction is almost the same because it’s measured as a percentage (more blood in = more blood out)

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12
Q

what is cardiac output

A

total volume of blood pumped by heart in 1 min
CO = HR x SV
- one of the most important determinants of exercise performance

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13
Q

what is the difference in CO at rest between trained and untrained

A

similar
- trained have higher SV but lower HR

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14
Q

what is the fick equation

A

oxygen uptake is equal to the product of Q and oxygen extraction

VO2 = Q x a-VO2 difference

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15
Q

how to measure the variables in the fick equation

A

VO2 = measured on metabolic cart - non invasive

Q = calculate indirectly - non invasive (similar to ECG)

a-VO2 difference = calculate directly
- invasive - not easy to measure
- need to insert catheter in artery and vein and measure the difference between the two

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16
Q

how do HR, SV, and a-VO2 difference change with exercise intensity

A

HR - increases linearly
SV - increases and plateaus (around 30-50% of VO2 max)
a-VO2 difference - increases linearly

17
Q

what is intrinsic regulation of HR

A

heart can maintain it’s own rhythm (~100bpm)
- SA node = pacemaker

18
Q

what are the factors involved in extrinsic regulation of HR

A

PNS/SNS
central motor command
endocrine (norepi/epi)
peripheral input

19
Q

what is the effect of PNS and SNS on HR

A

PNS decreases HR - predominate at rest
- inputs to SA node, and AV node (concentrated in the atria)

SNS increases HR - predominate during exercise
- inputs to myocardium (whole heart)

20
Q

what is the effect of central motor command on HR

A

signals for motor activity
increases HR

21
Q

what is the effect of norepi/epi on HR

A

increases HR (part of SNS)

22
Q

what is the effect of peripheral input on HR (mechanoreceptors)

A

decrease HR
- baroreceptors keep HR down during rest
- muscle metaboreceptors decrease HR (parasympathetic)

23
Q

what is the effect of peripheral input on HR (chemoreceptors)

A

increases HR
- group III/IV afferents more active during exercise

24
Q

what are the factors determining EDV (not infinite)

A

venous return
- how much blood from periphery can push back to the heart

ventricular distensibility
- how much the heart can increase in size (elasticity of the heart)

25
Q

what are the factors determining ESV (not infinite)

A

ventricular contractility
- how hard the heart can contract

aortic (or pulmonary artery) pressure
- limited capacity

26
Q

what are the 3 factors affecting venous return

A

muscle pump
- helps the most during exercise

respiratory pump
- vacuum that chest cavity can create

valves located in veins

27
Q

why is there a gradual decrease in SV during prolonged constant intensity exercise

A

less venous return due to water loss (sweating), fluid shifts, and blood flow redistribution

results in increased HR to make up for low BP

28
Q

what is the frank starling law of the heart

A
  • stretching ventricle increases force of contraction
  • greater EDV yields a greater SV
  • due to heart contraction and elasticity (within physiological limits)

KNES 373 (28 decks)

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