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CardioPulmRenal > Cardiac Output & Contractility > Flashcards

Cardiac Output & Contractility Flashcards

1
Q

Define preload.

A

amt. of blood ready to be pumped

L ventricle end-diastolic volume

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2
Q

Define venous pressure

A

pressure in the vena cava

can be used to estimate atrial pressure

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3
Q

Why is ventricular end-diastolic pressure the most accurate estimate of preload?

A

it takes into account the amt of blood AND the muscle fiber length at the end of diastole

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4
Q

Define afterload.

A

-pressure against which the heart must work to eject blood during systole

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5
Q

What happens to afterload if arterial pressure increases?

A

afterload increases

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6
Q

What happens to cardiac output (in the immediate time) as preload increases and as preload decreases?

A
  • cardiac output increases as preload increases

- cardiac output decreases as preload decreases

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7
Q

What happens to cardiac output (in the immediate time) as afterload increases and as afterload decreases?

A
  • cardiac output decreases as afterload increases

- cardiac output increases as afterload decreases

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8
Q

What happens to cardiac output (in the immediate time) as contractility increases and as contractility decreases?

A
  • cardiac output increases as contractility increases

- cardiac output decreases as contractility decreases

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9
Q

What is the positive staircase effect?

A
  • as heartbeats get closer together, less calcium is removed from the cell b/w beats
  • thus, contractility increases d/t extra calcium being taken up in the sarcoplasmic reticulum
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10
Q

What is the equation for stroke volume?

A

SV = EDV - ESV

end-diastolic volume minus end-systolic volume

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11
Q

What is a normal approximate stroke volume in a healthy adult?

A

70mL

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12
Q

What is the equation for cardiac output?

A

HR x SV

heart rate multiplied by stroke volume

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13
Q

What is a normal approximate cardiac output in a healthy adult?

A

5 L/min

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14
Q

What is the equation for ejection fraction?

A

EF = SV/EDV

stroke volume divided by end-diastolic volume

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15
Q

What is a normal approximate ejection fraction in a healthy adult?

A

55%

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16
Q

What does it mean it something has a positive inotropic effect?

A

contractility is increased

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17
Q

What type of receptors affect cardiac contractility when receiving sympathetic input?

A

beta-1

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18
Q

What is the sympathetic influence on calcium channels in the sarcoplasmic reticulum?

A

phosphorylated

activated to release calcium

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19
Q

What is the sympathetic influence on troponin I?

A

phosphorylation

-reveals binding sites to allow for muscle ctx

20
Q

What type of receptor affects cardiac contractility when receiving parasympathetic input?

A

muscarinic

21
Q

True or False: the ventricles receive parasympathetic input

A

False

22
Q

During what phase of the action potential does parasympathetic input have the most influence?

A

phase 4

23
Q

What are the ionic effects of parasympathetic input?

A
  • decreases calcium entering the cell during the phase 2 plateau
  • increases K+ leaving the cell
24
Q

On a pressure-volume loop diagram, what does point 1 represent and what cardiac activity happens after reaching point 1?

A

end-diastolic volume

–isovolumetric ctx

25
Q

On a pressure-volume loop diagram, what does point 2 represent and what cardiac activity happens after reaching point 2?

A

aortic valve opens

–ventricular ejection

26
Q

At what part of the pressure-volume loop does the ventricular pressure reach its maximum?

A

b/w pts 2 and 3

27
Q

On a pressure-volume loop, what does point 3 represent and what cardiac activity happens after reaching point 3?

A

aortic valve closes

–isovolumetric relaxation

28
Q

On a pressure-volume loop, what does point 4 represent and what cardiac activity happens after reaching point 4?

A

tricuspid valve opens

–ventricular filling

29
Q

What is represented by the width of the pressure-volume loop?

A

stroke volume

30
Q

What is represented by the area within the pressure-volume loop?

A

stroke work

31
Q

How is the pressure-volume loop affected when afterload changes?

A
  • afterload increase
  • -loop gets taller
  • afterload decrease
  • -loop gets shorter
32
Q

How is the pressure-volume loop affected when the preload changes?

A
  • preload increase
  • -loop gets wider
  • preload decrease
  • -loop gets narrower
33
Q

How is the pressure-volume loop affected when the contractility changes?

A
  • increased contractility
  • -gets taller and wider (on the left)
  • decreased contractility
  • -gets shorter and narrower on the left
34
Q

What is stroke work?

A

work done by the L ventricle to eject blood during one cardiac cycle

35
Q

What is the equation for cardiac output in regards to oxygen (Fick Principle)?

A

CO = O2 consumption / ([O2pv] - [O2pa])

36
Q

What is the effect on cardiac output of blood returning to the heart with an abnormally low level of oxygen?

A

it takes more oxygen to re-oxygenate the blood and thus decreases cardiac output according to the Fick principle

37
Q

What happens to cardiac output as right atrial pressure iincreases?

A

cardiac output increases up to a certain point and then reaches a plateau

38
Q

What happens to venous return as right atrial pressure increases?

A

venous return decreases

39
Q

With a positive inotropic effect, what happens (in the immediate time) to cardiac output and venous return?

A

cardiac output increases

venous return increases

40
Q

With a positive inotropic effect, what happens (in the immediate time) to right atrial pressure so that cardiac output and venous return stay in equilibrium?

A

right atrial pressure decreases

41
Q

With a negative inotropic effect, what happens (in the immediate time) to cardiac output and venous return?

A

cardiac output decreases

venous return decreases

42
Q

With a negative inotropic effect, what happens (in the immediate time) to right atrial pressure so that cardiac output and venous return stay in equilibrium?

A

right atrial pressure increases

43
Q

What happens to cardiac output and venous return when total peripheral resistance changes?

A

as TPR increases, CO and venous return decrease

as TPR decreases, CO and venous return increase

44
Q

What happens to cardiac output and venous return (in the immediate time) when blood volume increases?

A

cardiac output increases

venous return increases

45
Q

What happens to right atrial pressure when blood volume increases, so that equilibrium b/w cardiac output and venous return is maintained?

A

right atrial pressure decreases

46
Q

What happens to right atrial pressure when blood volume decreases, so that equilibrium is maintained b/w cardiac output and venous return?

A

right atrial pressure increases

CardioPulmRenal (18 decks)

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