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Circulation > Cardiac cycle, ECG, Physiology > Flashcards

Cardiac cycle, ECG, Physiology Flashcards

1
Q

What is the normal sequence of heart contraction and relaxation?

A
  1. Atria contract
  2. Ventricles contract
  3. Ventricles and atria both relax
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2
Q

The tricuspid and mitral valves are called _

A

The tricuspid and mitral valves are called atrioventricular valves
* They are open during filling ventricles but close during contraction of ventricles

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3
Q

The pulmonary valve and aortic valve are called _

A

The pulmonary valve and aortic valve are called semilunar valves

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4
Q

The volume in the ventricles following atrial systole, just prior to their contraction is called the _

A

The volume in the ventricles following atrial systole, just prior to their contraction is called the end-diastolic volume (EDV)

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5
Q

At rest, atrial contraction only contribues about 10% of the blood that fills the ventricles; the other 90% comes from _

A

At rest, atrial contraction only contribues about 10% of the blood that fills the ventricles; the other 90% comes from passive venous return during diastole

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6
Q

When the heart beat is increased, both systole and diastole shorten; however, _ is shortened more

A

When the heart beat is increased, both systole and diastole shorten; however, diastole is shortened more than systole
* During tachycardia atrial contraction becomes more important
* Atrial contraction might account for 40% of blood in this case

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7
Q

Phase 1 of the cardiac cycle is _

A

Phase 1 of the cardiac cycle is atrial contraction

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8
Q

Phase 2 of the cardiac cycle is _

A

Phase 2 of the cardiac cycle is isovolumetric ventricular contraction
* This is the first phase of ventricular systole

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9
Q

What happens during isovolumetric ventricular contraction phase?

A
  • Isovolumetric = no blood moves out
  • The pressure in the pulmonary artery and aorta are still greater
  • The purpose is to increase the pressure in the ventricles so that ventricular ejection can occur
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10
Q

Once the pressure in the ventricles becomes greater than the pressure in the atria, the _ valves close

A

Once the pressure in the ventricles becomes greater than the pressure in the atria, the atrioventricular valves close
* This marks the start of isovolumetric ventricular contraction

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11
Q

What marks the end of isovolumetric ventricular contraction?

A

Semilunar valves open; this happens once the pressure in the ventricles exceeds the pressure in the great vessels –> semilunar open to allow blood flow –> begin rapid ejection phase

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12
Q

Phase 3 of the cardiac cycle is _

A

Phase 3 of the cardiac cycle is rapid ventricular ejection

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13
Q

Phase 4 of the cardiac cycle is _

A

Phase 4 of the cardiac cycle is reduced ventricular ejection

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14
Q

Phase 4 of the cardiac cycle, the last phase of ventricular systole is called _

A

Phase 4 of the cardiac cycle, the last phase of ventricular systole is called reduced ventricular ejection

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15
Q

In which phase of the cardiac cycle do venticules get to the end-diastolic volume?

A

Atrial systole: marks the EDV

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16
Q

After reduced ventricular ejection, is phase 5, _

A

After reduced ventricular ejection, is phase 5, isovolumetric ventricular relaxation
* The pressure within the great vessels is now greater than ventricular pressure so aortic and pumonary valves close
* Atriventricular valves are also still closed

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17
Q

Phase 6 is _ , when _ occurs

A

Phase 6 is rapid ventricular filling , when atrioventricular valves open and blood rapidly refills the ventricles

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18
Q

Phase 7 of the cardiac cycle is _

A

Phase 7 of the cardiac cycle is reduced ventricular filling
* Ventricular slows as the pressure gradient decreases
* Brings us back to phase 1, atria contraction

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19
Q

The dicrotic notch occurs just after _

A

The dicrotic notch occurs just after closing of the aortic valve
* Due to rebound of the elastic aorta

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20
Q

Coronary blood flow peaks during _ phase of the cardiac cycle

A

Coronary blood flow peaks during isovolumetric relaxation phase of the cardiac cycle

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21
Q

The greatest oxygen demand of the heart occurs during _ phase of the cardiac cycle

A

The greatest oxygen demand of the heart occurs during isovolumetric contraction

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22
Q

The QRS lines up with _ phase of the cardiac cycle

A

The QRS lines up with isovolumetric contraction phase; this is when ventricular depolarization occurs

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23
Q

S1 heart sound occurs during _ phase of the cardiac cycle

A

S1 heart sound occurs during isovolumetric contraction

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24
Q

S2 heart sound occurs during _ phase

A

S2 heart sound occurs during isovolumetric relaxation

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25
Q

The pressure of the internal jugular vein is a good estimate of the _ pressure

A

The pressure of the internal jugular vein is a good estimate of the right atrium pressure

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26
Q

We often see _ sign in patients with disorders that involve elevated right atrial pressure

A

We often see jugular vein distention (JVD) in patients with disorders that involve elevated right atrial pressure

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27
Q

A measured JVD > 3 cm indicated elevated central venous pressure which is often seen in _

A

A measured JVD > 3 cm indicated elevated central venous pressure which is often seen in right sided heart failure (inability to empty the right ventricle)

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28
Q

The “a wave” represents _

A

The “a wave” represents atrial systole

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29
Q

The “c wave” represents _

A

The “c wave” represents ventricular contraction causing the tricuspid valve to protrude into the atrium
* C for cusp

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30
Q

The “x descent” represents _

A

The “x descent” represents atrial relaxation and less back pressure into the right atrium from the ventricle

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31
Q

The “v wave” represents _

A

The “v wave” represents atrial venous filling

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32
Q

The “y descent” represents _

A

The “y descent” represents ventricular filling where blood is leaving the right atrium

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33
Q

The S1 sound comes from the closing of the _ valves

A

The S1 sound comes from the closing of the tricuspid and mitral valves
* The pressure in the ventricles during systole causes these valve to close

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34
Q

_ is our “lub” sound

A

S1 is our “lub” sound

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35
Q

_ is our “dub” sound

A

S2 is our “dub” sound

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36
Q

S2 sound comes from the closing of _

A

S2 sound comes from the closing of aortic and pulmonary valves
* The ventricles begin to relax during diastole and the pressure drops below the pulmonary trunk and aorta which closes the valves

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37
Q

Describe physiologic splitting of S2

A

S2 is normally heard as two separate closures of the aortic and pulmonary valves in quick succession
* These are called A2 and P2
* Splitting of S2 can be heard in a normal individual during inspiration

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38
Q

The S2 sound is normally split during (expiration/ inspiration)

A

The S2 sound is normally split during inspiration

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39
Q

Name three types of pathologic S2 splitting

A
  1. Wide-split S2
  2. Fixed-split S2
  3. Paradoxical (reversed) splitting
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40
Q

Wide-Split S2

A

Wide-Split S2: means that a normal S2 split is exaggerated; during expiration a small split is heard and during inspiration, a widened split will be heard

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41
Q

Wide-Split S2 is caused by any condition that delays the closure of the _

A

Wide-Split S2 is caused by any condition that delays the closure of the pulmonary valve (P2)
* Pulmonary arterial hypertension right ventricle must pump against steeper pressure gradient
* Right bundle branch block depolarization of the right ventricle is slowed
* Pulmonary stenosis pulmonary valve is stiff and moves slowly

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42
Q

Fixed-Split S2

A

Fixed-Split S2: the S2 split can be heard equally wide in expiration and inspiration

43
Q

A fixed-split S2 is mostly associated with _ defects

A

A fixed-split S2 is mostly associated with atrial septal defect (ASD)
* There is an abnormal hole in the septum that separates LA from RA (blood flows left atrium–> right atrium)
* Extra blood goes to right ventricule –> extra blood goes to pulmonary valve –> delays closure

44
Q

Paradoxical Splitting

A

Paradoxical splitting occurs from a condition that delays aortic valve closure
* Aortic stenosis
* Involves splitting during expiration instead of inspiration
* P2 occurs before A2

45
Q

Sometimes we can have an additional heart sound, S3 during _

A

Sometimes we can have an additional heart sound, S3 during rapid ventricular filling (right after S2)
* Ken .. tuck-ky (S1.. S2,S3)
* We should not be able to hear ventricular filling normally –> indicates overfilled ventricle

46
Q

In a normal child or athlete, an S3 sound represents _

A

In a normal child or athlete, an S3 sound represents tensing of the chordae tendineae around the AV valve during ventricular filling
* S3 gallops are also normal pregnant women who have high cardiac output states

47
Q

Pathologically, S3 presents in patients with volume overload such as _

A

Pathologically, S3 presents in patients with volume overload such as aortic valve regurg or dilated cardiomyopathy

48
Q

S4 heart sound also occurs after S2 but later in diastole; it is generally pathologic and occurs from _

A

S4 heart sound also occurs after S2 but later in diastole; it is generally pathologic and occurs from ventricular walls that are stiff and noncompliant
* Longstanding hypertension
* Aortic stenosis
* We are hearing the stiff walls recoil against the atrial kick

49
Q

Cardiac output equation

A

CO = SV * HR

50
Q

The heart rate is controlled by the autonomic nervous system and can be altered by changing the firing rate of _

A

The heart rate is controlled by the autonomic nervous system and can be altered by changing the firing rate of SA node

51
Q

_ is the volume of blood expelled from the heart during one heartbeat (mL)

A

Stroke volume is the volume of blood expelled from the heart during one heartbeat (mL)

52
Q

Stroke volume is proportional to contractility, which in most patients is determined by _

A

Stroke volume is proportional to contractility, which in most patients is determined by amount of calcium available in the cytoplasm

53
Q

Digoxin (increases/ decreases) contractility by _ calcium levels; it is called an _

A

Digoxin increases contractility by increasing calcium levels; it is called an inotrope

54
Q

An inotropic effect is one that _

A

An inotropic effect is one that increases intracellular calcium and contractility

55
Q

The sympathetic nervous system increases contracility of the heart (atria and ventricles) by activating _ receptors

A

The sympathetic nervous system increases contracility of the heart (atria and ventricles) by activating beta1 receptors

56
Q

The degree of ventricular stretching at the end of diastole is called _

A

The degree of ventricular stretching at the end of diastole is called preload
* Stroke volume is proportional to preload

57
Q

The two parameters that can estimate preload are _ and _

A

The two parameters that can estimate preload are end-diastolic volume and end-diastolic pressure

58
Q

Frank Starling Law

A

Frank starling law: stroke volume increases as preload increases

59
Q

As sarcomere length increases, the number of actin and myosin cross bridges _ and contractility _

A

As sarcomere length increases, the number of actin and myosin cross bridges increases and contractility increases

60
Q
A
61
Q

A decreases in intrathoracic pressure will cause preload to (increase/ decrease)

A

A decreases in intrathoracic pressure will cause preload to increase
* Inverse relationship between intrathoracic pressure and preload
* When you take a deep breath, more venous blood returns to the heart

62
Q

Afterload is the _

A

Afterload is the pressure against which the ventricle must work to eject blood from the heart

63
Q

In normal physiology, the afterload is mostly determined by _

A

In normal physiology, the afterload is mostly determined by systemic vascular resistance
* This can be estimated by arterial blood pressure
* Afterload is inversely related to cardiac output

64
Q

People with high blood pressure (hypertension) often have (high/low) systemic vascular resistance and (high/ low afterload)

A

People with high blood pressure (hypertension) often have high systemic vascular resistance and high afterload
* Aortic stenosis also increases afterload

65
Q

The cardiac function curve plots _ on the x-axis and _ on the y-axis

A

The cardiac function curve plots EDV on the x-axis and cardiac ouput on the y-axis

66
Q

Dobutamine and digoxin are both _ drugs which (increase/decrease) contractility

A

Dobutamine and digoxin are both inotropic drugs which increase contractility

67
Q

(True/ False) The greater the pressure difference between the venous system and the right atrium, the greater the flow back to the heart

A

True; The greater the pressure difference between the venous system and the right atrium, the greater the flow back to the heart
* So a higher right atrial pressure, the smaller the venous return

68
Q

The vascular function curve measures _ on the x-axis and _ on the y-axis

A

The vascular function curve measures right atrial pressure on the x-axis and venous return on the y-axis

69
Q

The right artrial pressure at which the venous return becomes zero is called the _ ; it is the point when venous pressure is equal to the right atrial pressure

A

The right artrial pressure at which the venous return becomes zero is called the mean circulatory filling pressure ; it is the point when venous pressure is equal to the right atrial pressure

70
Q

As venous tone increases, venous return (increases/ decreases)

A

As venous tone increases, venous return increases

71
Q

As afterload increaes, venous return (increases/ decreases)

A

As afterload increaes, venous return decreases but MCFP does not change!

72
Q

If we graph the cardiac and vascular function curves on the same graph, we get an intersection where the cardiac output matches the venous return and the system operates at a steady state; this is called the _

A

If we graph the cardiac and vascular function curves on the same graph, we get an intersection where the cardiac output matches the venous return and the system operates at a steady state; this is called the steady-state operating point

73
Q
A
74
Q

Which represents a vasoconstricting drug like NE and which represents a vasodilator like a calcium channel blocker?

A

Point 1: vasoconstricting drug like NE
Point 2: vasodilator like a calcium channel blocker

75
Q

When does the mitral valve close?

A
76
Q

When does the aortic valve open?

A
77
Q

When does the mitral valve open?

A
78
Q

When does the aortic valve close?

A
79
Q

Determine systolic and diastolic BP from the graph

A
80
Q

The area within the pressure-volume curve represents _

A

The area within the pressure-volume curve represents stroke work
* This is force exerted by LV times the volume ejected

81
Q

What does this PV loop represent?

A

Increased preload

82
Q

What does this PV loop represent?

A

Increased afterlod

83
Q

What does this PV loop represent?

A

Increased contractility

84
Q

Drugs that cause vasodilation like ACE inhibitors are useful in treating heart failure because they are able to _

A

Drugs that cause vasodilation like ACE inhibitors are useful in treating heart failure because they are able to decrease afterload

85
Q

With an increase in contractility, the end-systolic pressure-volume relationship (ESPVR) line gets (steeper/ flatter)

A

With an increase in contractility, the end-systolic pressure-volume relationship (ESPVR) line gets steeper

86
Q

Explain how the SA node, which can be spontaneously depolarized, gets activated by the sympathetic nervous system

A
  1. NE activates B1 receptors in the heart
  2. B1 receptor activation increases cAMP
  3. cAMP triggers the opening of more HCN channels (mixed Na+/ K+ channels that conduct funny current)
  4. Spontaneous depolarization
87
Q

Positive chronotropy means _

A

Positive chronotropy means elevation of heart rate (via SA node activation)

88
Q

Sympathetic innervation can also cause faster contraction through the AV node, which is called _

A

Sympathetic innervation can also cause faster contraction through the AV node, which is called positive dromotropy
* Instead of funny current, increasing inward Ca2+ steepens the AV node curve

89
Q

SNS also directly increases _ which is termed positive inotropy

A

SNS also directly increases cardiomyocyte contractility which is termed positive inotropy
1. Increases Ca2+ current
2. Increases SERCA activity, increasing amount of Ca2+ stored inside the sarcoplasmic reticulum

90
Q

Parasympathetic innervation of the heart via the vagus nerve is asymmetric; the right vagus mostly controls _ and left vagus mostly controls _

A

Parasympathetic innervation of the heart via the vagus nerve is asymmetric; the right vagus mostly controls SA node and left vagus mostly controls AV node

91
Q

PNS will decrease the rate of the SA node in what is called _

A

PNS will decrease the rate of the SA node in what is called negative chronotropy

92
Q

PNS will also decrease depolarization of the AV node in what is called _

A

PNS will also decrease depolarization of the AV node in what is called negative dromotropy

93
Q

(True/ False) PNS causes negative inotropy

A

False; the PNS does not innervate ventricular cardiomyocytes so it has little to no direct effect of myocardial contractility

94
Q

Blood pressure equation

A

BP = CO * SVR

95
Q

The SNS has implications in blood pressure regulation because of its influence on _ specifically

A

The SNS has implications in blood pressure regulation because of its influence on vascular tone (impacts SVR)

96
Q

Increasing SNS, (increases/ decrease) vascular tone

A

Increasing SNS, increases vascular tone (vasocontriction)

97
Q

The net effect of NE on the vasculature is _

A

The net effect of NE on the vasculature is vasoconstriction
a1: vasoconstriction
b2: vasodilation

98
Q

SNS is involved in BP control via three mechanisms:

A
  1. SNS stimulates renin from juxtaglomerular cells via b1 activation –> kidneys absorb sodium and water –> increase blood volume
  2. SNS constricts renal afferent arteriole (a1 receptors) –> decreases GFR
  3. Stimulates sodium reabsorption from renal tubules
99
Q

Pacemaker cells have action potentials that lack step _ and _

A

Pacemaker cells have action potentials that lack step 1 and 2

100
Q

What happens at each step of the cardiac myocyte AP?

A
101
Q

Explain the difference between a voltage-gated Na+ channel that is resting vs. inactivated

A

Resting channel: closed; there is no ion movement but it is able to open in response to depolarization
Inactivated channel: no ion movement and it is unable to open due to absolute refractory period; inactivation gate is blocking it

102
Q

Describe the steps of the nodal cell action potential

A
103
Q
A

Circulation (12 decks)

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