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BRS (Bioregulatory Systems) > Cardiac Cycle > Flashcards

Cardiac Cycle Flashcards

1
Q

What is the cardiac cycle?

A

The cardiac cycle is a series of consecutive and simultaneous contractions and relaxations of the heart, to ensure a continuous flow of blood & circulation around the body.

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2
Q

What is Ventricular diastole?

A

Diastole: Ventricular relaxation during which the ventricles fill with blood. Preload attributed to isometric contractions and stretching of an intracellular network of the cardiomyocyte.

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3
Q

How many phases are present during diastole?

A

4 phases

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4
Q

How many phases are present during systole?

A

3 phases

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5
Q

What is systole?

A

Systole: Ventricle contraction generates pressure, ejecting blood into the arteries for both pulmonary and systemic circulation. Ventricular systolic contractions are isotonic (Involves sarcomere shortening), exerting an active force.

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6
Q

What type of contractions occur during ventricular systole?

A

Isotonic contractions, exerting an active force

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7
Q

What type of contractions occur during ventricular diastole, and isovolumetric systolic contraction?

A

Isometric contractions

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8
Q

What is an isovolumetric contraction?

A

Pressure builds up in ventricles, however ventricles do not expel blood until pressure overcomes afterload.

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9
Q

At what point does ventricular ejection proceed?

A

Pressure generated during isovolumetric contractions exceeds afterload

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10
Q

What phases occur after isovolumetric contraction?

A

Ventricular ejection and relaxation

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11
Q

What enables ventricular filling?

A 
Passive filling of blood through pressure gradient into ventricle from atria.
Atrial contraction (Systole)
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12
Q

What is End Diastolic volume (EDV)?

A

Volume of ventricles prior to systole

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13
Q

What is End-systolic volume (ESV)?

A

Volume in the ventricles proceeding isotonic ventricular contraction, and expulsion of blood

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14
Q

What is stroke volume?

A

The volume of blood expelled from the left ventricle during ventricular systole
EDV-ESV

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15
Q

What is the ejection fraction (EF)?

A

Proportion of the end diastolic volume that is ejected into systemic circulation during systole.

SV/EDV

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16
Q

What does EF illustrate?

A

The contractility of the heart

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17
Q

What is the normal ejection fraction?

A

65%

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18
Q

What is the typical EF for patients with heart failure?

A

35%

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19
Q

How does blood passively fill the ventricles?

A

Prior to atrial systole, the blood passively flows through the atrioventricular orifice through the mitral and tricuspid valve

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20
Q

What is the valve between the right atrium and right ventricle?

A

Tricuspid Valve

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21
Q

What is the left atrioventricular valve?

A

Mitral valve

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22
Q

What happens to the pressure during atrial filling (Atrial diastole)?

A

Pressure of atrium increases

P of atrium > p ventricle

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23
Q

How is atrial contraction stimulated?

A

Waves of excitation from the sinoatrial node

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24
Q

How is atrial systole depicted on the ECG?

A

P wave

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25
Q

What is the abnormal heart sound due to valve incompetency?

A

S4

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26
Q

What is S4?

A

Turbulent blood flow through dysfunctional valve closure.

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27
Q

What causes s4?

A

Pulmonary embolism,
Congestive heart failure
Tricuspid incompetennce

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28
Q

Which valves are closed during isovolumetric contraction?

A

Atrioventricular and semi lunar valves are closed

pressure is accumulating

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29
Q

Describe the pressure gradient during an isovolumetric contraction?

A

Ventricular pressure > atrial pressure

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30
Q

Describe the interval of the isovolumetric contraction?

A

Interval between the AV valves closing, and the semi-lunar valves opening

31
Q

What signifies ventricular excitation on an ECG?

A

QRS complex

32
Q

What heart sound is heard during the atrioventricular valve closure?

A

S1

33
Q

What is S1?

A

The closure of the atrioventricular valves. (Lub)

34
Q

What phase proceeds isovolumic contraction?

A

Ventricular ejection phase

35
Q

What is the ventricular ejection phase?

A

Period at which the ventricular pressure exceeds aortic and pulmonary pressure (afterload)
Semi lunar valves open

36
Q

What type of contraction is associated with the ventricular ejection phase?

A

Isotonic contraction (Sarcomere shortening)

37
Q

What volume resides post-ventricular ejection?

A

End-systolic volume

Residual volume in the ventricles

38
Q

What is the C wave?

A

Atrial pressure caused by the right ventricular contraction *(Pushing tricuspid valve into atrium)

39
Q

What type of electrical activity is demarcated on the ECG during the ventricular ejection phase?

A

None

No heart sounds, no valves are closing

40
Q

What phase succeeds ventricular ejection?

A

Reduced ejection

41
Q

What is reduced ejection?

A

END of ventricular systole.

Blood is ejected from the ventricles at a reducing rate as ventricular pressure decreased with volume reduction

42
Q

What happens after reduced ejection?

A

Aortic and pulmonary pressure increases, exceeds ventricular pressure, and closes semi-lunar valves

43
Q

How is reduced ejection depicted on an ECG?

A

T wave

44
Q

Why is a T wave shown during reduced ejection?

A

Cardiac cells are undergoing repolarisation to resting potential

45
Q

What phase succeeds reduced ejection?

A

Isovolumetric relaxation

46
Q

What phase does isovolumetric ventricular relaxation belong to?

A

Diastole

47
Q

What happens during isovolumetric relaxation?

A

Ventricular muscle relaxes, pressure on blood within the ventricles decrease.
pressure ventricles

48
Q

What sounds is produced during isovolumetric relaxation?

A

Dicrotic notch

49
Q

What is the dicrotic notch?

A

Caused by the rebound pressure against aortic valve as distended aortic wall relaxes./

50
Q

What happens to semi-lunar valves during isovolumetric relaxation?

A

Semi-lunar valves (Aortic and pulmonary) close to prevent back flow to the ventricles
AV valves close

51
Q

Why does the ventricular volume remain unchanged during isovolumetric relaxation?

A

The atrioventricular valves and semi-lunar valves are closed, thus there is no blood flow exchange between chambers

52
Q

What is the second heart sound attributed to?

A

Closure of semi-lunar valves

53
Q

What stage succeeds isovolumetric relaxation?

A

Rapid ventricular filling

54
Q

What occurs during rapid ventricular filling?

A

Atrial pressure increases (ventricular pressure decreases via relaxation)
Generates pressure gradient,
Enables blood flow through atrioventricular orifice into the ventricles
This increases ventricular volume, simultaneously decreases atrial pressure

55
Q

How does rapid ventricular filling occur?

A

Filling of ventricles is passive, not due to atrial systole.

56
Q

Why does abnormal S3 occur?

A

Signifies turbulent ventricular filling, attributed to severe hypertension or mitral incompetence

57
Q

What is s3 referred as to?

A

Ventricular Galloop

58
Q

How is rapid ventricular filling depicted on an ECG?

A

Isoelectric ECG between cardiac cycles

59
Q

What cardiac phase succeeds rapid ventricular filling?

A

Reduced passive filling

60
Q

What are the changes to the ECG during reduced passive filling?

A

There are no changes to the ECG.

Atrial contraction is redundant

61
Q

What occurs during passive ventricular filling?

A

Slow filling of ventricles (Diastasis), ventricular volume increases slowly (Reduction in pressure gradient)

62
Q

How do the patterns of pulmonary circulation pressures compare on either side of the heart?

A

The patterns are identical, however quantitatively, the pressure in the right < left

63
Q

Quantitatively, how does the volume ejected by the ventricles compare?

A

Identical ejection volumes between left and right ventricles

64
Q

How can pressure changes in the pulmonary artery be detected?

A

Insertion of catheter with ballooon into the pulmonary artery, inflation of balloon prevents blood flow

Distal, pressure system of left atrium measured

65
Q

What is pulmonary artery wedge pressure (PAWP)?

A

Possible to measure the preload on the left side

PAWP is elevated when there is left atrium or mitral valve dysfunction

66
Q

What happens at Point A of the pressure-volume loop?

A

Mitral valve closure (increase in ventricular pressure) Isovolumetric contraction (Preload)

67
Q

What occurs between A-B within pressure-volume loops?

A

Ventricular systole isovolumetric contractions:

Increase in left ventricular pressure, volume remains same

68
Q

What occurs at stage B within pressure-volume loops?

A

Diastolic blood pressure

69
Q

What occurs between B and C within the pressure-volume loops?

A

Ejection of blood during isotonic ventricular contraction

Ventricular systole.

70
Q

How is pulse pressure measured on the pressure-volume loops?

A

Systolic blood pressure - Diastolic blood pressure

71
Q

How is systolic blood pressure measured on a pressure-volume loop?

A

Peak of the loop

72
Q

What occurs during point C on a pressure-volume loop?

A

Aortic valve closes (Dub)

73
Q

When does the aortic valve open?

A

Point B

74
Q

What happens between C and D on a pressure-volume loop?

A

Isovolumetric relaxation; Left ventricular pressure decreases for the same ventricular volume.
AV and semi-lunar valves closed.

BRS (Bioregulatory Systems) (38 decks)

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