Lecture 14 - CO, BP, VR Flashcards

1
Q

cardiac output is equal to what

A

heart rate x stroke volume

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2
Q

cardiac index is equal to what

A

cardiac output / BSA

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3
Q

stroke volume is determined by

A

preload, contractility, afterload

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4
Q

what are the 4 determinants of cardiac output

A
  1. heart rate
  2. preload
  3. contractility
  4. afterload
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5
Q

describe preload

A

all factors contributing to passive ventricular wall stress or tension at the end of diastole

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6
Q

what is the most important factor in stretching cardiac muscle

A

venous return

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7
Q

what are the 3 outcomes of the frank-starling mechanism

A
  1. regulating moment to moment changes in SV
  2. responsible for balancing outputs of L and R ventricles
  3. prevents “back-up” of blood on one side of the heart
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8
Q

Venous return is equal to

A

the difference in mean systemic filling pressure and right atrial pressure

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9
Q

increased venous return will ____ ventricular filling and ____ stronger contractions

A

increase; increase

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10
Q

what 4 factors influence venous return

A
  1. blood volume
  2. venous compliance
  3. skeletal muscle pump
  4. respiratory pump
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11
Q

T/F: an increase in venous return will increase cardiac output

A

TRUE

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12
Q

what are 4 things used to estimate preload

A
  1. venous return
  2. hydration/dehydration
  3. pressure in atria/ventricle
  4. central venous pressure
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13
Q

what is compliance

A

relationship of V / P and the distensibility of ventricles

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14
Q

T/F: a compliant ventricle is stiff

A

FALSE - easily stretched

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15
Q

why would ventricles lose compliance

A
  1. ischemia
  2. age
  3. heart disease
  4. infiltrative disease
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16
Q

if a ventricle is ______ it will require higher pressure to fill

stiff or compliant

17
Q

describe afterload

A
  • tension generated in ventricular myocardium for ejection
  • inversely proportional to stroke volume
18
Q

how is the afterload estimated

A
  1. ventricular myocardial wall tension
  2. systemic vascular resistance
  3. diastolic BP
19
Q

T/F: systolic arterial BP is a good index of afterload

20
Q

define contractility

A

the speed with which myocytes would contract if no load were placed on the heart

21
Q

contractility will increase due to the increase in what

22
Q

stroke volume and contractility are ____ related

A

directly; increase/decrease with each other

23
Q

B1 adrenergic receptors

A
  • binds epinephrine and norepinephrine
  • increases intracellular calcium
24
Q

decreased contractility is a mark of

A

cardiac disease (DCM, myocarditis)

25
contractility is estimated by
1. LV ejection fraction 2. LV change in diameter
26
T/F: heart rate and pulse rate are different
TRUE
27
T/F: acetylcholine causes a negative chronotropic effect
TRUE
28
pressure drop across the vascular bed is
the product of cardiac output and systemic vascular resistance
29
systolic BP
highest pressure during ventricular systole
30
diastolic BP
the lowest pressure during ventricular diastole
31
Mean arterial pressure
organ perfusion pressure; correlates with diastolic value
32
normal blood pressure in dogs
120/80 (90)
33
what must be the mean arterial pressure to maintain organ perfusion
60 mmHg
34
what are the determinants of blood pressure
1. cardiac output 2. peripheral vascular resistance 3. blood volume 4. blood viscosity 5. elastic or arterial walls
35
how is BP directly measured
arterial catheter
36
how is BP indirectly measured
doppler flow oscillometric BP