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<3 > Cardiac Cycle And Sounds > Flashcards

Cardiac Cycle And Sounds Flashcards

1
Q

Where does the fast action potential occur inc radial tissue?

A

In atrial and ventricular myocytes

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2
Q

Where does the slow action potential of cardiac tissue occur?

A

In SA and AV nodes

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3
Q

What results in the slow action potential of the SA and AV nodes?

A

Influx of Ca instead of Na

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4
Q

What are the phases of the fast action potential in hte atrial and ventricular myocytes?

A

Phase 1 - initial repolarization

Phase 2 - plateau phase

Phase 3 - Repolarization

Phase 4 - heart at rest

Phase 0 - rapid upsweep

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5
Q

What occurs in Phase 1 of the Fast Action potential seen in cardaic tissue?

A

Initial repolarization

  • na channel closed (na doesn’t enter)
  • voltage gated k channel open (k leaves)

—> causes cell to become more negative and repolarize

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6
Q

What occurs in Phase 2 of the Fast Action potential seen in cardaic tissue?

A

Plateau phase

  • ca channels open, Ca (+) leaves
  • k channels still open
  • negative and positive charges leaving stabilize RMP at more positive value
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7
Q

Why is there no phase 2 in the Slow action potential of SA and AV node tissue?

A

Bc SA and AV node tisssue is NOT contractile

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8
Q

What occurs in Phase 3 of the Fast Action potential seen in cardaic tissue?

A

Repolarization

  • ca channels close
  • voltage gated k channels still open
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9
Q

What occurs in Phase 4 of the Fast Action potential seen in cardaic tissue?

A

Heart at rest

  • Na, K and Ca voltage gated channels = clsoed
  • cell at normal RMP = -70 - -90 mV
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10
Q

What occurs in Phase 0 of the Fast Action potential seen in cardaic tissue?

A

Rapid upswept

  • voltage gated Na Chanel opens
  • cell is rapid DEPOLARIZED
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11
Q

What are the phases seen in the SLow Action Potential of SA and AV nodal tissue?

A

Phase 4 - resting membrane potential (heart at rest)

Phase 0 - depolarization via Ca

Phase 3 - repolarization

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12
Q

What occurs in Phase 4 of the Slow Action potential seen in cardaic tissue?

A

Resting membrane potential

  • steady depolarization (never a plateua phase)
  • Open Funny Na channels
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13
Q

How do funny sodium channels contribute to heart rate?

A

How fast theses channels open
—> faster the depolarization
—> faster SA cells to threshold
—> faster HR

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14
Q

Where are most Funny Na channels located?

A

Most are at SA node

^why the SA node serves as heart’s pacemaker
(brought to threshold fastest)

2nd most at AV node (backup pacemaker)

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15
Q

What occurs in Phase 0 of the Slow Action potential seen in cardaic tissue?

A

Depolarization via Ca

  • influx of Ca from extracellular fluid via ca channels
  • ca is larger than Na causes a slower influx and overall slower rate of depolarization
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16
Q

What occurs in Phase 3 of the SLow Action potential seen in cardaic tissue?

A

Repolarization

-K leaves via its voltage gated channels

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17
Q

What does a P wave mean on a normal ECG?

A

Atrial depolarization

-initiated by SA node depolarization (influx of Na)

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18
Q

What does a QRS complex mean on a Normal ECG?

A

Represent Ventricular Depolarization

Sum of all phase 0s - depolarization

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19
Q

What wave is hidden in the QRS complex?

A

Wave for atrial REpolarization

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20
Q

What does the T wave represent on a normal ECG?

What permeability would be high?

A

Ventricular Repolarization

K potassium permeability is high

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21
Q

Where is the PR interval?

What does it represent?

A

P wave —> beginning of QRS

Represents time for depolarization to pass from ATRIA to VENTRICLES via AV node

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22
Q

What is the most important determinant of the PR interval?

A

Slow conduction velocity of the AV node

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23
Q

What would we see when there is damage to the AV Node?

A

Prolonged PR interval

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24
Q

Where is the ST Segment?

What does it represent?

What has high permeability at this time?

A

End of QRS —> beginning of T wave

Represent Phase 2 of fast actin potential (plateau)

Ca has high permeability (will leave to help counter-act the K leaving)

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25
Q

Where is the QR interval?

What does it represent?

A

Beginning of QRS —> end of T-wave

Represent total time any ventricular myocytes are depolarized

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26
Q

What does the Cardaic cycle start with in the Wigger’s diagram?

A

Starts w/ P wave in ECG

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27
Q

What does the x-axis of the Wigger’s diagram represent?

A

Time (ms)

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28
Q

What are the units of the Y-axis of the Wigger Diagram?

A

Volume (mL) or pressure (mmHg)

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29
Q

What are the 4 pressures tracked on the Wigger’s Diagram?

A

Aortic pressure

Ventricular pressure

Atrial pressure

Jugular venous pressure

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30
Q

What do changes in pressure produce?

A

Volume changes

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31
Q

What is the route of blood thru the heart after entering via the Inferior and Superior Vena Cava?

A
  1. Blood enters via inferior and superior vena cava
  2. O2 poor blood —> RA
  3. RA —tricuspid valve —> RV (atrial contraction)
  4. RV contracts (ventricular contraction)
  5. RV —pulmonic valve —> Pulmonary A. —> lungs
  6. Lungs —> Pulmonary Vs.
  7. Pulmonary Vs. w/ Oxygen rich blood —> LA
  8. LA —bicuspid valve (mitral) —> LV (atrial contraction)
  9. LV —aortic valve —> aorta —> body
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32
Q

What is the Dicrotic Notch produced by?

A

Produced by closing of the aortic valves as ventricles relax

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33
Q

What is the A-wave?

A

Result of atrial contraction

Increase in atrial pressure

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34
Q

What is the C -wave?

A

Coincides with ventricle contraction

Increase in atrial pressure bc of AV bulgin backward

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35
Q

What causes a V -wave?

A

Due to venous return accumulating in atria (causing increase in atrial pressure)

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36
Q

The jugualr pressure curve is same as what other pressure curve?

A

Atrial

Due to non-functional valve b/w jugular v. And RA

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37
Q

What is the End Systolic volume?

When is it measured?

A

Lowest volume of blood in the ventricle @ ~50 mL

Measured right after aortic valve closes (end of systole)

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38
Q

What is the End-diastolic volume?

A

When the volume is at maximum capacity

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39
Q

When is hte rapid filling phase?

A

Tuburlen blood flow into the ventricles rapidly increased ventricular volume

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40
Q

When is the first heart sound heard?

A

W/ closing of AV valves at beginning of Period of Isovolumetric Contraction

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41
Q

When is the 2nd heart sound heard?

A

W/ closing of Aortic/Pulmonic Valves

Aka same time as Dicrotic notch in aortic pressure wave

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42
Q

When is the 3rd heart sound heard?

A

Period of rapid filling of ventricle after AV valve opens

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43
Q

When is the 4th heart sound heart?

A

When blood is being forced into ventricle during atrial contraction

44
Q

What can cause abnormal heart sounds (2)?

A

Blood going in Wrong Direction (regurgitation)

Blood has trouble going in the RIght direction (stenosis)

45
Q

What do almost all murmurs reflect?

A

Changes to the valves

46
Q

What is stenosis of a valve?

A

Narrowing

Valve doesn’t fully open when it is supposed to making it hard for proper blood flow

47
Q

What is regurgitation?

A

Valve can’t close or stay close

Blood will flow in wrong direction

48
Q

What is a systolic Murmur?

A

Murmur is superimposed b/w lub and dub (during ventricular systole)

49
Q

What are the 2 things that can cause a systolic murmur?

A
  1. Stenosis of Aortic/pulmonic valves (would normally be open)
  2. Regurgitation of AV valves
    (Should be closed)
50
Q

What are the two things that can cause a Diastolic Murmur?

A
  1. Regurgitation of Aortic/pulmonic valves (should be closed)
  2. AV valve stenosis (should be open)
51
Q

At the P-wave, how are the atria and ventricles?

A

Both in diastol

52
Q

How is the electrical activity at time of the P wave?

A

P-wave = atrial depolarization

  • Both atrial and ventricular myocytes are in Phase 4 (RMP)
  • SA and AV node in Phase 4 (RMP w/ funny Na channels)
53
Q

What are the physical conditions of the heart during the P-wave?

A

P-wave = atrial depolarization

  • AV valve open, Aortic/pulm. Valves closed
  • both atria & ventricle at rest
  • blood is entering ventricles
54
Q

What is the atrial pressure @ diastole?

A

4 mmHg

55
Q

What is the ventricular pressure during Diastole?

A

Close to 0 (allows blodo from atria to get into ventricles)

56
Q

At the P wave, how are the pressures of the Pulmonary a., aorta and jugular v.?

A

PA and Aorta approaching diastolic values bc blood is moving to periphery

Jugualr v. Has higher pressure than both atria and ventricle (so blodo can leave it)

57
Q

The rate at which blood leaves the aorta/pulmonary a. Is determined by what?

A

By the resistance to blood flow

Vascoconstriction = high resistance = higher diastolic pressure

Vasodilation = low resistance = lower diastolic pressure

58
Q

Atrial contraction causes what changes in pressure?

A

Increases atrial pressure slightly

Increases ventricular pressure too

59
Q

What causes the delay in ventricular contraction?

A

Delayed ventricular depolarization due to slow conduction velocity thru AV Node

** this is crucial to normal functioning of the heart

60
Q

Ventricular contraction causes what changes in pressure?

A

Increases ventricular pressure to get up to systolic pressure (120 mmHg)

Slightly increases atrial pressure bc of reverse building of AV valve

61
Q

Ventricular relaxation causes what changes in pressure?

A

Decreases ventricular pressure until it is in diastole

62
Q

What are heart sounds a result of?

A

Result of vibrations produced by blood moving (to not being able to move)

63
Q

What does atrial systole do?

A

Atrial systole = atrial contraction

Will top off ventricular volume and produce the 4th heart sound

64
Q

What does Ventricular systole start rom?

A

Start from level added by Atria

65
Q

How is aortic pressure affected by atrial systole?

A

It is not affected

-it will continually decrease during as blood leaves aorta for periphery

66
Q

At the end of atrial systole, how are the conditions of the heart?

A
  • atria is relaxing, pressure decreasing
  • AV valves are open
  • aortic/pulmonary valves are closed
  • QRS complex has/is occurring
67
Q

What happens to ventricular pressure at the beginning of ventricular systole?

A

Rapidly increases and exceeds atrial pressure w/in milliseconds

Causes AV vlaves to close = first heart sound

68
Q

What is the first heart sound caused by?

A

Closing of AV valves that causes the blood entering the atria to hit the now closed valve/cardiac structure

69
Q

How are the aortic/pulmonic valves during ventricular systole?

What does this cause?

A

Aortic/pulmonic valves are closed

Causes Period of unchanged ventricular volume
—> Isovolumetric contraction period

70
Q

What happens during the Peirod of Isovolumetric contractioN?

A

Ventricle contract, increase the pressure

Causes AV valves to bulge back and increases atrial pressure
(thus increases venous pressure)

Aortic pressure decreases

71
Q

How are AV valves prevented from everting during the Period of Isovolumetric contraction?

A

Prevented from everting by contraction of the papillary muscles attached to the valve leaflets

72
Q

What will end isovolumetric contraction?

A

The opening of the Aortic/pulmonic valves

73
Q

What are the normal blood pressure of the Aorta?

A

120 = when aortic valve is opened

70 = when aortic valve is closed and just about to open

74
Q

What is the Normal blood presssure of the Pulmonary a.?

A

25 = when pulmonary valve open

15 = when pulmonary a. Is in diastole

75
Q

In order to open the pulmonary valve or aortic valve, ventricular pressure must be greater than what?

A

Must be greater than the diastolic pressure in each artery

Greater than 70 and greater than 15

76
Q

What happens to the ventricular volume and pressure as ejection of blood occurs?

A

Ventricular volume decreases

Ventricular pressure initially increase to peak systolic pressure and as ejection occurs, it drops

77
Q

What causes the drop in ventricular pressure during the ejection of blood?

A

Due to,

  1. Less blood in ventricle
  2. Less able to generate pressure (squeezing on something empty)
78
Q

What is occurring, electrically, during the ejection of blood?

A

T-wave occurs (depolarization of ventricular myocytes)

-need this to occur so we can enter ventricular relaxation)

79
Q

What happens to the aortic pressure during ejection of blood

A

Initially increases and then slowly declines as blood leaves to go to periphery

80
Q

What happens t atrial prssure during the ejection of blodo?

A

Atrial pressure increases due to blood accumulating in atria

81
Q

What happens to ventricular and aortic pressure during ventricular relaxation?

A

Pressure drop

-ventricle pressure drops faster than aortic pressure

82
Q

What is the rate of blood moving into he periphery dictated by?

A

Total peripheral resistance (TPR)

83
Q

What is Total Peripheral resistance determined by?

A

By how much vasoconstriction/vasodilation there is

84
Q

When do the aortic/pulmonary valves close?

A

When Pventricle < Paorta/pulmonary

85
Q

What does the closing of the Aortic/pulmonic valves cause?

A

Causes S2 and dicrotic notch

86
Q

What causes the Dicrotic notch?

A

The dip and rapid rise in aortic blood pressure is cause by back flow of blood when aortic/pulmonic valves close

(Is quickly corrected as blood that moved backward resumes normal direction of flow)

87
Q

What is occurring during the Period of Isovolumetric relaxation ?

A

AV and aortic/pulmonic valves = closed

Ventricle is relaxing, pressure dropping

Pressure in aorta also dropping (though slow)

88
Q

When does the Peirod of Isovolumetric relaxation end?

A

When Patria > Pventricle

89
Q

What will the venous return of blood to the atrium cause?

A

Causes gradual increase in atrial pressure

Opens AV valves

90
Q

How is Ventricle filling initially?

A

Initially is a rapid process bc blood has acccumulated in atria

blood hitting left over blood = 3rd heart sound

91
Q

What causes the slow filling of the ventricle?

A

Filling slows down due to Elastic Recoil of Ventricle

92
Q

What is the Period of slowed filling called?

A

Diastasis

93
Q

What does the heart spend the majority of its time in?

A

Diastole

94
Q

What will a change in heart rate affect more, diastole or systole?

A

Diastole

95
Q

What will a fast HR sacrifice?

Causes a decrease in what?

A

Will sacrifice ventricular filling time, decreases BP

96
Q

What will a low HR do?

A

Causes prolonged diastole

97
Q

What is the A-wave in the jugular pressure graph:

A

Atrial contraction

Pressure generated by contraction is reflected back into the great veins bc of non functioning valves

98
Q

What is the C wave in the jugualr pressure curve?

A

C-wave = isovolumetric contraction Peirod

Bulging of AV valves, increases atrial pressure, therefore increasing jugular pressure

99
Q

What is the V-wave in the Jugular pressure curve?

A

V wave = ventricular contraction

  • blood begins to accumulate in atria, increasing pressure, therefore venous pressure is also higher
100
Q

How is pressure on the right side of the heart compared to the left?

A

Lower pressure due to low resistance in pulmonary vascular bed

101
Q

What is th pressure of the

Right ventricle compared to Left V.?

A

P-RV = 20/0

P-LV = 120/0

102
Q

What is the prssure of the

Pulmonary a. Vs the aortic a. ?

A

P-PA = 25/15

P-aorta = 120/80

103
Q

How does the amount of blood pumped differ form the RV to LV?

A

No difference

RV = LV

104
Q

How do the pressure curves change from R side of heart to L?

A

Pressure curves have the same shape but different amplitudes

105
Q

What side are normal heart sounds heard from?

A

They are heard from BOTH sides, not just left

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