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Physiology > EKG > Flashcards

EKG Flashcards

1
Q

Sinus rhythm:

A
  • EKG pattern obtained under normal resting conditions

- spontaneous depolarization generated at SA node

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2
Q

Sinus rhythm is under…

A

parasympathetic dominated output

- 70 to 80 bpm

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3
Q

Arrhythmias:

A

changes in pattern or rate

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4
Q

Disturbances of impulse initiation can come from…

A

SA node or ectopic focus

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5
Q

Altered SA rhythms:

A

changes in rate and timing but not sequence of wave forms

  • waves all present and normal
  • cycle duration is altered
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6
Q

Altered SA rhythms are stimulated by…

A

ANS

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7
Q

Sinus tachycardia HR is…

A

> 100 bpm

- generated by SNS input

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8
Q

Sinus bradycardia HR is…

A

< 60 bpm

- generated by PNS input

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9
Q

Ectopic foci is where…

A

conduction is initiated from somewhere other than SA node

- at AV node and Purkinje fibers

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10
Q

Altered ectopic foci causes:

A

change in sequence or relative timing

  • some waves may be absent or timing is completely off
  • can produce extra systole or premature beat followed by compensatory pulse
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11
Q

Chronic/maintained activity:

A

repeated, rapid discharges

- greater frequency than SA node

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12
Q

Examples of chronic/maintained activity:

A
  • atrial/ventricular paroxysmal tachycardia
  • atrial fibrillation
  • ventricular tachycardia
  • ventricular fibrillation
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13
Q

Atrial/ventricular paroxysmal tachycardia is caused by…

A

irregular firing of initiating signals, pathway problems, and circuit rhythms

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14
Q

Atrial/ventricular paroxysmal tachycardia:

A
  • appears for short while
  • ventricular condition is more serious
  • predisposes someone to more serious arrhythmias
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15
Q

Atrial fibrillation:

A

atrial rate is greater then 350 bpm

- not usually life threatening

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16
Q

Causes of atrial fibrillation are often…

A

age related

  • HTN
  • mitral valve problem
  • smoking
  • alcohol
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17
Q

Dangers of atrial fibrillation:

A
  • lack of blood moving

- causes blood clots to form in atria

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18
Q

Ventricular tachycardia:

A

elevated ventricular contraction sup to 230 bpm

- more serious due to cardiac output

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19
Q

Causes of ventricular tachycardia:

A
  • obese
  • associated with heart diseases
  • post heart surgery
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20
Q

Ventricular fibrillation:

A
  • most serious
  • totally uncoordinated contractions, which causes ineffective pumping
  • life threatening if not treated ASAP
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21
Q

Causes of ventricular fibrillation:

A
  • sudden electrical shock of heart
  • ischemia of muscle, conducting system, or both
  • response to certain drugs
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22
Q

Ventricular fibrillation can cause unconsciousness w/in…

A

4-5 seconds of onset due to lack of blood flow to brain

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23
Q

Disturbances of impulse propagation leads to…

A

conduction blocks and reentrant rhythms

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24
Q

Blocks:

A

delay of transmissions along conducting system

  • 1st degree
  • 2nd degree
  • 3rd degree
  • bundle branch
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25
Q

1st degree AV block:

A

abnormal prolongation of AV conduction time

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26
Q

2nd degree AV block:

A

all QRS complexes preceded by P wave, but not all P waves followed by QRS

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27
Q

3rd degree AV block:

A

atrial and ventricular rhythms entirely independent

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28
Q

Bundle branch block:

A

reentry arrhythmias

- can produce extra systoles

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29
Q

Cardiac cycle begins at…

A

SA node

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30
Q

A pressure graph records pressures from…

A
  • L atria
  • L ventricle
  • aorta
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31
Q

Phonocardiogram shows…

A

closing of valves

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32
Q

3 graphs in cardiac cycle:

A
  • pressure
  • volume
  • EKG
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33
Q

Pressure changes in a pressure graph is due to…

A
  • volumes in each area

- contraction of atria and ventricles

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34
Q

Volume changes on the volume graph are due to…

A

changes associated with L ventricle

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35
Q

EKG shows the…

A

electrical events associated with the heart

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36
Q

EKG is influenced by…

A

extrinsic control mechanisms

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37
Q

Systole:

A

time period associated w/ contraction

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38
Q

What happens during systole:

A
  • pressure rises

- blood moves out of contracted chamber

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39
Q

Diastole:

A

time period associated with relaxation

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40
Q

What happens during diastole?

A
  • pressure drops

- blood moves into relaxed chambers

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41
Q

Before heart beat is initiated: what happens during quiescent time?

A

atria and ventricles in diastole

  • T-P interval on EKG
  • on isoelectric line
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42
Q

Before heart beat is initiated, which valves are open and which are closed?

A
  • AV valve open
  • semilunar valve closed
  • no heart sounds
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43
Q

Before heart beat is initiated, blood moves from…

A

high pressure in aorta to low pressure in atria and ventricles

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44
Q

Before heart beat is initiated, ventricles are…

A

filling for about 70% of the time

  • 110 mL volume
  • happens because pressure is very low
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45
Q

Before heart beat is initiated, what valve prevents backflow of blood from aorta/pulmonary artery?

A

semilunar valves

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46
Q

Before heart beat is initiated, pressure in R atrium is…

A

0-3 mmHg

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47
Q

Before heart beat is initiated, pressure in aorta is…

A

slowly dropping as blood moves into arteries

- about 90 mmHg

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48
Q

At initiation of heart beat, SA node…

A

slowly depolarizes, which causes impulse to spread across atria
- caused by funny Na+ channels

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49
Q

At initiation of heart beat, atrial fast myocytes…

A

depolarize and appears as P wave on EKG

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50
Q

At atrial systole, blood from where is being emptied?

A

atria into ventricles

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51
Q

Atrial systole occurs during…

A

ventricular diastole (at 0.1 second)

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52
Q

Atrial systole is represented by…

A

P-R interval on EKG

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53
Q

At atrial systole, atrial contraction begins at what part of EKG?

A

peak of P wave

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54
Q

At atrial systole, atrial contraction causes an…

A

increase in atrial pressure b/c atrium pushes blood into ventricle
- leads to increase in ventricular pressure (preload)

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55
Q

At atrial systole, atrial contraction will cause a small amount of blood to…

A

move back into the veins since there is no valve to prevent backflow
- this is the pulse in the jugular vein

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56
Q

At atrial systole, pressure in the aorta is…

A

dropping, but still above ventricular pressure

- means no blood is flowing to aorta

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57
Q

At atrial diastole, what is being relaxed?

A

atria

- decrease in pressure here

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58
Q

Atrial diastole occurs during…

A

ventricular depolarization QRS

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59
Q

T/F: you can see atrial diastole on an EKG

A

F

60
Q

At ventricular systole, what is being emptied?

A

ventricles into the arteries (aorta and pulmonary trunk)

61
Q

Ventricular systole occurs at how many seconds?

A

0.3 seconds

62
Q

At ventricular systole, the ventricular depolarization is represented by what on the EKG?

A

QRS complex

63
Q

At ventricular systole, the start of the QRS complex is the end of…

A

the filling period

  • end diastolic volume (EDV): max volume before contraction
  • L ventricle volume is about 120-130 mL
64
Q

At ventricular systole, the middle of the QRS complex represents…

A

initial contraction of ventricle

- pressure in ventricle is greater than atrium

65
Q

At ventricular systole, what valve is closed during the middle of the QRS complex?

A
  • aortic semilunar valve

- mitral (AV) valve: makes LUBB noise

66
Q

At ventricular systole, initial contraction of heart is what type of contraction?

A

isovolumetric: same amount of blood is entering and exiting the ventricles
- leads to sharp rise in ventricular pressure

67
Q

At ventricular systole, what happens when pressure in the ventricle is greater then the pressure in the aorta?

A

isovolumetric contraction ends

- aortic semilunar valve and pulmonary semilunar valve open

68
Q

At ventricular systole, what happens after isovolumetric contraction?

A

period of rapid ejection

  • increased pressure ventricle as size of ventricle decreases due to contraction
  • blood is forced from ventricle through open semilunar valve into aorta
69
Q

At ventricular systole, what happens when blood is forced from ventricle through open semilunar valve into aorta?

A
  • decrease of blood volume in left ventricle

- cuspid valve stays closed so no backflow into atria

70
Q

At ventricular systole, what is represented by the T wave on the EKG?

A

ventricular repolarization, which begins and ends during ventricular systole

71
Q

At ventricular systole, what happens during ventricular repolarization?

A

Ca2+ levels in ventricular myocytes drop

72
Q

At ventricular systole, what happens at the end of the T wave?

A
  • decreased force of contraction, which leads to decreased ventricular pressure
  • decreased volume of blood ejected
  • elastic recoil of aorta
  • atrial pressure rises slowly
73
Q

At ventricular systole, what is the pressure comparison between aorta and ventricles during ventricular repolarization?

A

pressure in aorta > pressure in ventricles

74
Q

At ventricular systole, what valve closes at the end of the T wave?

A

aortic semilunar valve

- makes DUBB noise

75
Q

At ventricular diastole, what is being relaxed?

A

ventricles

76
Q

Ventricular diastole occurs at how many seconds?

A

0.4 seconds

77
Q

Ventricular diastole is represented by what wave interval on the EKG?

A

T-Q interval

78
Q

At ventricular diastole, what mechanical events occur?

A
  • isovolumetric relaxation
  • rapid filling phase
  • slow filling phase
79
Q

At ventricular diastole, what occurs during isovolumetric relaxation?

A
  • both AV and semilunar valves are closed
  • ventricular pressure drops sharply
  • volume of ventricles is constant
  • end systolic volume (ESV): volume left in ventricle at end of systole (about 40-60 mL)
80
Q

At ventricular diastole, when does isovolumetric relaxation end?

A

pressure of ventricle < pressure in atrium

- mitral valve opens

81
Q

At ventricular diastole, what contributes to the rapid filling phase?

A

volume of blood accumulated in atrium during ventricular systole

82
Q

At ventricular diastole, slow filling phase will continue to occur until…

A

next ventricular depolarization

83
Q

Stroke volume:

A

volume pumped per cardiac cycle (mL/beat)

- can be found by EDV - ESV

84
Q

What affects strength of contraction?

A

inotropic factors

85
Q

Stroke volume is affected by…

A

preload
- increased preload increases length of cardiac fibers, which will increase Ca2+ interaction with troponin and increase contractibility

86
Q

Cardiac output is the volume of blood…

A

pumped by one ventricle per min

87
Q

What is the cardiac output at rest?

A

5 mL/min

- total blood volume is circulated in 1 min

88
Q

What is the cardiac output during exercise?

A

increases to about x4-5 rest level

  • gets adjusted to meet metabolic demand
  • minimizes O2 requirements
89
Q

Cardiac output is increased by…

A
  • lowering heart rate and a higher stroke volume
  • decreased afterload
  • usually comes from increased EDV
90
Q

How do you find cardiac output?

A

HR x SV

91
Q

What factors affect heart rate?

A

chronotropic factors b/c HR action is on SA node

92
Q

Examples of local chronotropic factors:

A
  • temperature

- stretch

93
Q

Examples of outside chronotropic factors:

A
  • ANS
  • hormones
  • plasma electrolyte concentration
  • age
94
Q

HR can increase by…

A
  • decreasing PNS

- increasing SNS

95
Q

When PNS and SNS are both blocked, HR is…

A

at the intrinsic heart rate: 100 bpm

96
Q

PNS is a ____ chronotropic factor

A

negative

  • through vagus nerve
  • lacks direct effect on cytosolic CA2+ and contraction
97
Q

PNS uses what neurotransmitter?

A

ACh

- gets released at nerve terminals near SA and AV nodes

98
Q

ACh binds to what receptor in PNS?

A

muscarinic (M2) receptors that are coupled to special G-protein

99
Q

In the PNS, what happens when ACh binds to M2 receptor?

A
  • K+ channels opened
  • leads to hyperpolarization
  • decreases Ca2+ permeability
100
Q

In the PNS, ACh is rapidly broken down b/c of…

A

large amount of acetylcholinesterase

101
Q

Increase of PNS tone leads to…

A

decreased rate of depolarization of SA node

102
Q

PNS tone is predominant at…

A

rest

- resting HR of 70-80 bpm

103
Q

Excess stimulation of PNS can…

A

stop HR for several seconds or produce blocks

104
Q

SNS fibers will distribute as an…

A

extensive epicardial plexus (net) to chambers

105
Q

SNS releases…

A

norepi»epi

106
Q

SNS has a ____ chronotropic and inotropic effect on SA node

A

positive

107
Q

Norepi binds to what receptor?

A

beta receptor that is coupled to G-protein and cAMP mediated effects

108
Q

What happens when norepi binds to beta receptor?

A

VGC Ca2+ is activated

  • releases Ca2+ from SR
  • increased intracellular Ca2+, which leads to increased rate of depolarization and force development and max force developed
109
Q

Nerve terminals uptake most of…

A

norepi released

110
Q

What degrades norepi?

A

MAO

111
Q

Norepi reuptake is increased by…

A

phospholamban

- gets phosphorylated by SNS

112
Q

By re-uptaking most of the norepi released, there will be an increase Ca2+…

A
  • storage capacity for stronger and faster contraction

- reuptake for shorter duration of contraction, which leads to a decrease in cardiac cycle length of time

113
Q

What happens if HR increases too much?

A

decrease in filling time and force due to decreasing frank-starling mechanism

114
Q

Intrinsic regulation of myocardial performance:

A

contractile response to changes in resting length of myocardiocytes
- frank-starling mechanism

115
Q

Cardiac sensitivity of contractile protein changes as…

A

sarcomere length increases

116
Q

At resting HR, fibers are…

A

shorter than optimum length for force development

117
Q

Intrinsic regulation: When ventricular volume increases, what happens to the myocardial length?

A

increases

118
Q

Increase in VR leads to…

A

increase in EDV -> increase in preload -> increase in SV

119
Q

EDV is proportional to…

A

VR

120
Q

VR is enhanced by…

A
  • skeletal muscle pump
  • respiratory pump
  • sympathetic constriction of veins
121
Q

VR is enhanced by skeletal muscle pumps because…

A

skeletal muscle activity pushes against blood vessels, which pushes blood toward heart

122
Q

VR is enhanced by respiratory pumps because…

A

respiratory muscles expand thoracic cavity and lowers the pressure, which pulls blood toward heart

123
Q

VR is enhanced by sympathetic constriction of veins because…

A

it pushes more blood toward heart

124
Q

A chronologically enlarged heart leads to…

A
  • hypertrophy: more E is required for dilated heart to perform a given amount of external work compared to normal heart
  • hypertension
125
Q

Hypertension produces…

A

abnormal loads and hypertrophies often occur in selective chamber

126
Q

Extrinsic regulation of myocardial performance:

A

NS and chemical controls it

127
Q

inotropic factors affect force of contraction by…

A

altering intracellular Ca2+ levels

128
Q

Extrinsic regulation: chemical control such as via…

A

hormones

  • adrenal medulla secretes epi»norepi
  • SNS output helps control secretion of epi
  • binds to same receptor as norepi and has same effects (beta 1)
129
Q

intrinsic and extrinsic control mechanisms can…

A

work together (synergistic effects) to produce even greater stroke volume than either alone

130
Q

Drugs that increase/decrease intracellular Ca2+ levels will affect…

A

heart rate and contractibility

131
Q

Drugs: verapamil and other Ca2+ channel blocker leads to…

A

reduction in intracellular Ca2+

- decreases contractibility

132
Q

Drugs: digoxin and other cardiac glycosides lead to…

A

inhibition of Na+/K+ ATPase

  • increased Na+ inhibits activity of Na+/Ca2+ exchanger, therefore increased intracellular Ca2+
  • increased contractibility
133
Q

Myocardial contractility is influenced by…

A

preload and afterload

134
Q

Preload:

A

stretching of ventricle

  • due to filling with blood that alters Frank-Starling forces
  • improves efficiency of heart
135
Q

Afterload:

A

force opposing flow of blood from ventricles

- pressure in the aorta or pulmonary trunk

136
Q

Afterload is caused by…

A

high resistance

137
Q

Afterload decreases…

A

the efficiency of the heart

138
Q

Efficiency of heart is determined by…

A

ejection fraction

  • SV/EDVx100
  • usually 60-65% at rest
139
Q

P wave:

A

atrial depolarization

140
Q

QRS complex:

A

ventricular depolarization

- atrial repolarization included

141
Q

T wave:

A

ventricular repolarization

142
Q

PR interval:

A

atrial depolarization to ventricular depolarization

143
Q

PR segment:

A

electrical impulse conducted through AV node

144
Q

QT interval:

A

ventricular activity

145
Q

Deviation from ST interval may indicate…

A

myocardial ischemic damage

Physiology (33 decks)

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