Physiology > EKG > Flashcards

EKG Flashcards

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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
1st degree AV block:
abnormal prolongation of AV conduction time
26
2nd degree AV block:
all QRS complexes preceded by P wave, but not all P waves followed by QRS
27
3rd degree AV block:
atrial and ventricular rhythms entirely independent
28
Bundle branch block:
reentry arrhythmias | - can produce extra systoles
29
Cardiac cycle begins at...
SA node
30
A pressure graph records pressures from...
- L atria - L ventricle - aorta
31
Phonocardiogram shows...
closing of valves
32
3 graphs in cardiac cycle:
- pressure - volume - EKG
33
Pressure changes in a pressure graph is due to...
- volumes in each area | - contraction of atria and ventricles
34
Volume changes on the volume graph are due to...
changes associated with L ventricle
35
EKG shows the...
electrical events associated with the heart
36
EKG is influenced by...
extrinsic control mechanisms
37
Systole:
time period associated w/ contraction
38
What happens during systole:
- pressure rises | - blood moves out of contracted chamber
39
Diastole:
time period associated with relaxation
40
What happens during diastole?
- pressure drops | - blood moves into relaxed chambers
41
Before heart beat is initiated: what happens during quiescent time?
atria and ventricles in diastole - T-P interval on EKG - on isoelectric line
42
Before heart beat is initiated, which valves are open and which are closed?
- AV valve open - semilunar valve closed - no heart sounds
43
Before heart beat is initiated, blood moves from...
high pressure in aorta to low pressure in atria and ventricles
44
Before heart beat is initiated, ventricles are...
filling for about 70% of the time - 110 mL volume - happens because pressure is very low
45
Before heart beat is initiated, what valve prevents backflow of blood from aorta/pulmonary artery?
semilunar valves
46
Before heart beat is initiated, pressure in R atrium is...
0-3 mmHg
47
Before heart beat is initiated, pressure in aorta is...
slowly dropping as blood moves into arteries | - about 90 mmHg
48
At initiation of heart beat, SA node...
slowly depolarizes, which causes impulse to spread across atria - caused by funny Na+ channels
49
At initiation of heart beat, atrial fast myocytes...
depolarize and appears as P wave on EKG
50
At atrial systole, blood from where is being emptied?
atria into ventricles
51
Atrial systole occurs during...
ventricular diastole (at 0.1 second)
52
Atrial systole is represented by...
P-R interval on EKG
53
At atrial systole, atrial contraction begins at what part of EKG?
peak of P wave
54
At atrial systole, atrial contraction causes an...
increase in atrial pressure b/c atrium pushes blood into ventricle - leads to increase in ventricular pressure (preload)
55
At atrial systole, atrial contraction will cause a small amount of blood to...
move back into the veins since there is no valve to prevent backflow - this is the pulse in the jugular vein
56
At atrial systole, pressure in the aorta is...
dropping, but still above ventricular pressure | - means no blood is flowing to aorta
57
At atrial diastole, what is being relaxed?
atria | - decrease in pressure here
58
Atrial diastole occurs during...
ventricular depolarization QRS
59
T/F: you can see atrial diastole on an EKG
F
60
At ventricular systole, what is being emptied?
ventricles into the arteries (aorta and pulmonary trunk)
61
Ventricular systole occurs at how many seconds?
0.3 seconds
62
At ventricular systole, the ventricular depolarization is represented by what on the EKG?
QRS complex
63
At ventricular systole, the start of the QRS complex is the end of...
the filling period - end diastolic volume (EDV): max volume before contraction - L ventricle volume is about 120-130 mL
64
At ventricular systole, the middle of the QRS complex represents...
initial contraction of ventricle | - pressure in ventricle is greater than atrium
65
At ventricular systole, what valve is closed during the middle of the QRS complex?
- aortic semilunar valve | - mitral (AV) valve: makes LUBB noise
66
At ventricular systole, initial contraction of heart is what type of contraction?
isovolumetric: same amount of blood is entering and exiting the ventricles - leads to sharp rise in ventricular pressure
67
At ventricular systole, what happens when pressure in the ventricle is greater then the pressure in the aorta?
isovolumetric contraction ends | - aortic semilunar valve and pulmonary semilunar valve open
68
At ventricular systole, what happens after isovolumetric contraction?
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
At ventricular systole, what happens when blood is forced from ventricle through open semilunar valve into aorta?
- decrease of blood volume in left ventricle | - cuspid valve stays closed so no backflow into atria
70
At ventricular systole, what is represented by the T wave on the EKG?
ventricular repolarization, which begins and ends during ventricular systole
71
At ventricular systole, what happens during ventricular repolarization?
Ca2+ levels in ventricular myocytes drop
72
At ventricular systole, what happens at the end of the T wave?
- decreased force of contraction, which leads to decreased ventricular pressure - decreased volume of blood ejected - elastic recoil of aorta - atrial pressure rises slowly
73
At ventricular systole, what is the pressure comparison between aorta and ventricles during ventricular repolarization?
pressure in aorta > pressure in ventricles
74
At ventricular systole, what valve closes at the end of the T wave?
aortic semilunar valve | - makes DUBB noise
75
At ventricular diastole, what is being relaxed?
ventricles
76
Ventricular diastole occurs at how many seconds?
0.4 seconds
77
Ventricular diastole is represented by what wave interval on the EKG?
T-Q interval
78
At ventricular diastole, what mechanical events occur?
- isovolumetric relaxation - rapid filling phase - slow filling phase
79
At ventricular diastole, what occurs during isovolumetric relaxation?
- 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
At ventricular diastole, when does isovolumetric relaxation end?
pressure of ventricle < pressure in atrium | - mitral valve opens
81
At ventricular diastole, what contributes to the rapid filling phase?
volume of blood accumulated in atrium during ventricular systole
82
At ventricular diastole, slow filling phase will continue to occur until...
next ventricular depolarization
83
Stroke volume:
volume pumped per cardiac cycle (mL/beat) | - can be found by EDV - ESV
84
What affects strength of contraction?
inotropic factors
85
Stroke volume is affected by...
preload - increased preload increases length of cardiac fibers, which will increase Ca2+ interaction with troponin and increase contractibility
86
Cardiac output is the volume of blood...
pumped by one ventricle per min
87
What is the cardiac output at rest?
5 mL/min | - total blood volume is circulated in 1 min
88
What is the cardiac output during exercise?
increases to about x4-5 rest level - gets adjusted to meet metabolic demand - minimizes O2 requirements
89
Cardiac output is increased by...
- lowering heart rate and a higher stroke volume - decreased afterload - usually comes from increased EDV
90
How do you find cardiac output?
HR x SV
91
What factors affect heart rate?
chronotropic factors b/c HR action is on SA node
92
Examples of local chronotropic factors:
- temperature | - stretch
93
Examples of outside chronotropic factors:
- ANS - hormones - plasma electrolyte concentration - age
94
HR can increase by...
- decreasing PNS | - increasing SNS
95
When PNS and SNS are both blocked, HR is...
at the intrinsic heart rate: 100 bpm
96
PNS is a ____ chronotropic factor
negative - through vagus nerve - lacks direct effect on cytosolic CA2+ and contraction
97
PNS uses what neurotransmitter?
ACh | - gets released at nerve terminals near SA and AV nodes
98
ACh binds to what receptor in PNS?
muscarinic (M2) receptors that are coupled to special G-protein
99
In the PNS, what happens when ACh binds to M2 receptor?
- K+ channels opened - leads to hyperpolarization - decreases Ca2+ permeability
100
In the PNS, ACh is rapidly broken down b/c of...
large amount of acetylcholinesterase
101
Increase of PNS tone leads to...
decreased rate of depolarization of SA node
102
PNS tone is predominant at...
rest | - resting HR of 70-80 bpm
103
Excess stimulation of PNS can...
stop HR for several seconds or produce blocks
104
SNS fibers will distribute as an...
extensive epicardial plexus (net) to chambers
105
SNS releases...
norepi>>epi
106
SNS has a ____ chronotropic and inotropic effect on SA node
positive
107
Norepi binds to what receptor?
beta receptor that is coupled to G-protein and cAMP mediated effects
108
What happens when norepi binds to beta receptor?
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
Nerve terminals uptake most of...
norepi released
110
What degrades norepi?
MAO
111
Norepi reuptake is increased by...
phospholamban | - gets phosphorylated by SNS
112
By re-uptaking most of the norepi released, there will be an increase Ca2+...
- 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
What happens if HR increases too much?
decrease in filling time and force due to decreasing frank-starling mechanism
114
Intrinsic regulation of myocardial performance:
contractile response to changes in resting length of myocardiocytes - frank-starling mechanism
115
Cardiac sensitivity of contractile protein changes as...
sarcomere length increases
116
At resting HR, fibers are...
shorter than optimum length for force development
117
Intrinsic regulation: When ventricular volume increases, what happens to the myocardial length?
increases
118
Increase in VR leads to...
increase in EDV -> increase in preload -> increase in SV
119
EDV is proportional to...
VR
120
VR is enhanced by...
- skeletal muscle pump - respiratory pump - sympathetic constriction of veins
121
VR is enhanced by skeletal muscle pumps because...
skeletal muscle activity pushes against blood vessels, which pushes blood toward heart
122
VR is enhanced by respiratory pumps because...
respiratory muscles expand thoracic cavity and lowers the pressure, which pulls blood toward heart
123
VR is enhanced by sympathetic constriction of veins because...
it pushes more blood toward heart
124
A chronologically enlarged heart leads to...
- hypertrophy: more E is required for dilated heart to perform a given amount of external work compared to normal heart - hypertension
125
Hypertension produces...
abnormal loads and hypertrophies often occur in selective chamber
126
Extrinsic regulation of myocardial performance:
NS and chemical controls it
127
inotropic factors affect force of contraction by...
altering intracellular Ca2+ levels
128
Extrinsic regulation: chemical control such as via...
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
intrinsic and extrinsic control mechanisms can...
work together (synergistic effects) to produce even greater stroke volume than either alone
130
Drugs that increase/decrease intracellular Ca2+ levels will affect...
heart rate and contractibility
131
Drugs: verapamil and other Ca2+ channel blocker leads to...
reduction in intracellular Ca2+ | - decreases contractibility
132
Drugs: digoxin and other cardiac glycosides lead to...
inhibition of Na+/K+ ATPase - increased Na+ inhibits activity of Na+/Ca2+ exchanger, therefore increased intracellular Ca2+ - increased contractibility
133
Myocardial contractility is influenced by...
preload and afterload
134
Preload:
stretching of ventricle - due to filling with blood that alters Frank-Starling forces - improves efficiency of heart
135
Afterload:
force opposing flow of blood from ventricles | - pressure in the aorta or pulmonary trunk
136
Afterload is caused by...
high resistance
137
Afterload decreases...
the efficiency of the heart
138
Efficiency of heart is determined by...
ejection fraction - SV/EDVx100 - usually 60-65% at rest
139
P wave:
atrial depolarization
140
QRS complex:
ventricular depolarization | - atrial repolarization included
141
T wave:
ventricular repolarization
142
PR interval:
atrial depolarization to ventricular depolarization
143
PR segment:
electrical impulse conducted through AV node
144
QT interval:
ventricular activity
145
Deviation from ST interval may indicate...
myocardial ischemic damage
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