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Physiology > Cardiac Cycle > Flashcards

Cardiac Cycle Flashcards

1
Q

What fraction of time does the heart spend in diastole? Systole?

A 
Diastole = 2/3
Systole = 1/3
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2
Q

True or false: the cardiac cycle reduces in time in equal proportion to the increase in heart rate

A

False–not exactly proportional, although they are inversely related

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3
Q

Where are the precordial leads positive (toward the outside of the body, or on the inside near the heart)?

A

Outside, on the body wall

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4
Q

What is R wave progression?

A

The fact that the R wave increases in amplitude as your move through the precordial leads

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5
Q

What is corresponding event in the cardiac cycle to depolarization of the SA node?

A

Blood is returning to the right atrium

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6
Q

What is corresponding event in the cardiac cycle to atrial depolarization?

A

Atrial contraction

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7
Q

What is corresponding event in the cardiac cycle to depolarization of the AV node (specifically, the delay here)?

A

Ventricular filling

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8
Q

What is corresponding event in the cardiac cycle to depolarization of the bundle of His and the Purkinje fibers?

A

Ventricular contraction

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9
Q

What is corresponding event in the cardiac cycle to ventricular depolarization?

A

Blood expulsion to lungs or periphery

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10
Q

What are the units for cardiac cycle?

A

time/beat (inverse of HR, but not proportional)

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11
Q

True or false: diastolic periods reduce less proportionally than systole when you increase the heart rate

A

False–more than proportionally (i.e. as the heart rate goes up, the heart spends a larger amount of time in systole than would be expected if it were a linear relationship)

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12
Q

When is the heart perfused, during diastole or systole?

A

Diastole

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13
Q

When does isovolumic contraction occur, in ventricular systole or diastole?

A

Ventricular systole

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14
Q

When does isovolumic relaxation occur, in ventricular systole or diastole?

A

Ventricular Diastole

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15
Q

When does rapid ejection occur, in ventricular systole or diastole?

A

Ventricular systole

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16
Q

When does rapid filling occur, in ventricular systole or diastole?

A

Ventricular Diastole

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17
Q

When does atrial systole occur, in ventricular systole or diastole?

A

Ventricular Diastole and systole (bridges the two)

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18
Q

When does reduced ejection occur, in systole or diastole?

A

Ventricular systole

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19
Q

What are the seven periods of the cardiac cycle?

A
  1. Atrial systole
  2. Isovolumic contraction
  3. Rapid ejection
  4. Reduced ejection
  5. Isovolumic relaxation
  6. Rapid filling
  7. Reduced filling
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20
Q

What accounts for the increase in atrial pressure in the isovolumic ventricular contraction phase?

A

AV valve will bulge back into atrium

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21
Q

What accounts for the steady increase in atrial pressure in the rapid and reduced ventricular ejection phases?

A

Refilling of the atria from the venous system

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22
Q

What accounts for the drop in the atrial pressure in the rapid filling phase of the ventricle?

A

Blood flowing from atria and into the ventricles

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23
Q

What is the “a” wave in the atrial pressure curve?

A

The contraction of the atria

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24
Q

What causes the AV valves to close?

A

Atrial pressure dropping below the ventricular

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25
Q

What is the purpose of the chordae tendiae?

A

Ensure that the AV valves do not fold back into the atria (do NOT pull the valves open as is commonly believed)

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26
Q

What is the event that corresponds to the “c” wave of the atrial pressure curve?

A

The bulging of the AV valves back into the atria

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27
Q

What is occurring in the atria as the ventricles contract?

A

They fill

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28
Q

When in the cardiac cycle do the AV valves open (what is the corresponding event in the ventricles)?

A

Ventricular isometric relaxation

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29
Q

What does the “v” point on the atrial pressure curve correspond to?

A

Opening of the AV valves

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30
Q

Pathologic increases in right atrial pressure leads to what physical exam finding?

A

JVD

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31
Q

What relieves the increase in the atrial pressure that is caused by the AV valves bulging back?

A

Overall contraction of the heart

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32
Q

In what phase does the ventricular pressure increase dramatically?

A

Isovolumic contraction

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33
Q

What causes the increase in ventricular pressure during atrial systole?

A

Movement of blood into the ventricles from the atria

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34
Q

What is the “atrial kick”? What effect does this have on ventricular filling?

A

An expulsion of blood into the ventricle from the atria

Fills about another 15-20%

35
Q

True or false: in a normal, healthy individual, the atrial kick does not do much. It utilized more if the heart is under stress

A

True

36
Q

What causes the isovolumic stage of ventricular contraction to end? What is the next stage?

A

Opening of the semilunar valves

Next stage = repid ejection

37
Q

What does the aorta do to accomodate the rapid rise in pressure?

A

Balloons out

38
Q

For what fraction of time does the rapid ejection phase last compared to total systolic time?

A

1/3

39
Q

For what fraction of time does the reduced ejection phase last compared to total systolic time?

A

2/3

40
Q

What does the end of the ejection phase/ start of the isovolumic relaxation phase correspond to on an EKG?

A

T wave

41
Q

What causes the reduced ejection phase to end?

A

Closure of the semilunar valve

42
Q

What causes the end of the isovolumic relaxation phase?

A

Opening of the AV valve

43
Q

What happens to both the ventricular and atrial pressure in the rapid fillig phase? Why?

A

Falls, because there is passive distention of the walls

44
Q

What causes the reduced filling phase / increase in pressure in the atria and ventricles?

A

Active expansion of the walls of the heart

45
Q

What is the only factor that determines valve opening/closure?

A

Pressure differentials

46
Q

When does the abrupt rise in the aortic pressure curve end (which ventricular phase)?

A

Start of the rapid ejection phase

47
Q

What is the effect on systolic pressure of the aorta expanding to accommodate the blood its receiving?

A

Lowers the pressure

48
Q

What is the effect on the the aorta expanding to accommodate the blood its receiving on the flow of blood (once the valves are shut, that is)?

A

Increases the flow

49
Q

Why don’t the semilunar valves close after the ventricular pressure has fallen below aortic pressure?

A

Momentum of blood

50
Q

What accounts for the dicrotic notch (incisura) of the aortic pressure curve?

A

Due to the backward pressure wave returning from the periphery

51
Q

What causes the backward pressure wave (P aug on her graph) in the aorta?

A

The reflection of the pressure wave when it hits the bifurcation

52
Q

What is the first upstroke in pressure in the aorta caused by?

A

Blood flow from venticle to aorta

53
Q

What is the second upstroke in the pressure in the aorta caused by? (the “first shoulder”)

A

Due to the backward pressure wave returning from the periphery

54
Q

What is the third upstroke in the pressure in the aorta caused by? (the “secondshoulder”)

A

Systolic ejection

55
Q

What are the two major effects of a calcified aorta on aortic pressure? Why? (hint: one answer is obvious, the other has to do with the reflected pressure wave from the bifucation)

A

Increases greatly, because it cannot accommodate the rapid increase in pressure from the heart, AND the fact the blood flows faster through the calcified aorta down the artery, causing a larger reflected wave

56
Q

What determines the slope (rate) of the aortic pressure drop after systole?

A

The pressure in the periphery of the body

57
Q

What would happen to the slope of the aortic pressure line if peripheral resistance increased?

A

Become flatter

58
Q

What are the three events (in order) that occur when the AV valve opens?

A

Rapid ventricular filling
Decreased filling (diastasis)
Atrial contraction

59
Q

What happens once the AV valve closes?

A

isometric contraction

60
Q

What are the two events that occur when the semilunar valves open?

A

Rapid ventricular ejection

Decreased ventricular ejection

61
Q

What occurs when the semilunar valve closes?

A

Isometric relaxation

62
Q

When does the opening of the AV valves occur (systole or diastole)?

A

diastole

63
Q

When does the closing of the AV valves occur (systole or diastole)?

A

Systole

64
Q

When does the opening of the semilunar valves occur (systole or diastole)?

A

Systole

65
Q

When does the closing of the semilunar valves occur (systole or diastole)?

A

Diastole

66
Q

Through which period(s) of the cardiac cycle are the AV valves open?

(atrial systole, iso contract, rapid ejec, reduced ejec, iso relax, rapid filling, or reduced filling)

A

Atrial systole, then rapid and reduced filling

67
Q

Through which period(s) of the cardiac cycle are the semilunar valves open?

(atrial systole, iso contract, rapid ejec, reduced ejec, iso relax, rapid filling, or reduced filling)

A

Rapid ejection and reduced ejection

68
Q

When, in the cardiac cycle, are no valves open?

atrial systole, iso contract, rapid ejec, reduced ejec, iso relax, rapid filling, or reduced filling

A

Iso contraction and iso relaxation

69
Q

Review all of the things, including the ventricular volume changes during the cardiac cycle.

A

Don’t you dare click 5 yet

70
Q

What is the stroke volume?

A

The LVEDV - LVESV

left ventricular end diastolic volume - end systolic volume

71
Q

What cardiac event does S1 correspond to?

A

Closure of the mitral and tricuspid valves

72
Q

What cardiac event does S2 correspond to?

A

The closure of aortic and pulmonary valves

73
Q

What causes the physiological splitting of S2?

A

Delayed closure of the pulmonic valve OR

Early closure of the aortic valve

74
Q

Why would the pulmonary valve close late with inspiration (in terms of physiological splitting of S2)?

A

Greater venous return to the right heart increases the time it takes to expel all of the blood

75
Q

Why would the aortic valve close early with inspiration (in terms of physiological splitting of S2)?

A

Less blood returns to the left heart, so less time to change the pressure and close the valve

76
Q

If physiological splitting occurs, which event always comes first: closing of the aortic valve, or pulmonary valve?

A

Aortic before pulmonic

77
Q

When is an “opening snap” heard? What does this correspond to physiologically?

A

may be heard if the mitral or tricuspid is hard to open (e.g. in mitral stenosis d/t very fibrous, calcified mitral valve)

78
Q

What causes S3?

A

When the ventricular myocytes reach their maximum passive stretch length, and the chordae tendinae and AV ring are pulled taut by the stretched ventricle.

79
Q

What causes S4?

A

Pathological increase in ventricular pressure at the end of atrial systole (a stiffer ventricle)

80
Q

What causes a diastolic murmur?

A

Mitral valve stenosis

81
Q

What can cause a systolic murmur?

A

Leaflets not closing completely, causing turbulent blood flow through a partially closed valve

82
Q

What could be the causes of paradoxical splitting?

A

Any pathology that causes an increase in conduction through one ventricle more than another

83
Q

In a LBB, will a split be heard with inspiration or expiration? Why?

A

Expiration, since LV ia already delayed, and since the split will manifest itself as the pulmonic valve closing before the aorta

Physiology (75 decks)

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