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Bio 472 > The Heart, Cardiac Muscle Properties, the Electrocardiogram > Flashcards

The Heart, Cardiac Muscle Properties, the Electrocardiogram Flashcards

1
Q

location of the Heart

A

in the Pericardial Sac in the Mediastinal Cavity

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2
Q

Pericardial Sac

A

double walled sac containing the heart and the roots of the great vessels

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3
Q

Mediastinal Cavity

A

central compartment of the thoracic cavity,

surrounded by loose connective tissue

heart, vessels, esophagus, trachea, phrenic and cardiac nerves, thoracic duct, thymus and lymph nodes

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4
Q

Heart Wall parts

A
  1. Epicardium (visceral pericardium)
  2. Myocardium
  3. Endocardium
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5
Q

Epicardium (visceral pericardium)

A

serous membrane that makes up the innermost layer of the pericardial sac and the outermost layer of the heart wall

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6
Q

Myocardium

A

heart muscle, middle layer of the heart wall,

thickest layer of the heart

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7
Q

Endocardium

A

inner layer of the heart wall

similar to epithelial cells

makes up the surface of the valves

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8
Q

4 chambers of the heart

A

2 atria
2 ventricles

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9
Q

What blood enters the right atria?

A

deoxygenated blood from the vena cava

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10
Q

Where does the blood in the right ventricle go to?

A

pulmonary arteries which will take the blood to the lungs

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11
Q

What blood enters the left atria?

A

Oxygenated blood from the lungs/pumonary veins

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12
Q

Where does the blood in the left ventricle go?

A

aorta, which will carry blood throughout the body

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13
Q

Right Side of the Heart

A

deoxygenated blood, low pressure system, pumps blood to the lungs

“Pulmonary Circuit”

tricuspid valve, pulomonary semilunar valve

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14
Q

Left Side of the Heart

A

oxygenated blood, high pressure system, pumps blood to the body

“Systemic Circuit”

bicuspid valve (Mitral Valve), aortic semilunar valve

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15
Q

Cardiac Blood Supply

A
  1. Coronary Arteries(exit from Aorta)
  2. Capillaries
  3. Coronary Veins
  4. Coronary Sinus (outflow into Right Atrium)
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16
Q

Coronary Arteries

A

Branch off from the Aorta into the Left Coronary Artery and Right Coronary Artery

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17
Q

Coronary Veins

A

remove deoxygenated blood from the myocardium

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18
Q

Coronary Sinus

A

largest coronary vein, responsible for venous retuen for 55% of the cardiac blood supply

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19
Q

Cardiac Muscle Structure

A

distinct cells, striated,

Autorhythmicity, “Functional Synctium”

thick and thin filaments, intercalated disks=glue, branched fibers = twist

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20
Q

Autorhythmicity

A

autodepolarization or self-excitable

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21
Q

Functional Syncytium

A

wave of contraction that allows the heart to work as a unit,

breakdown of this causes Fibrillation

thin membranes in between cells, stimulate one cell and they all contract

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22
Q

Atria Autorhythmicity

A

70/min

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23
Q

Ventricle Autorhythmicity

A

20/min

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24
Q

Types of Cardiac Muscle Fibers

A
  1. Fast Response
  2. Slow Response
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25
Fast Response Fibers
Atrial and Ventricular Cells | 5 phases ## Footnote -90 to +30 mV, 2 Na+ gates (M gates, H gates)
26
M Gates
activation gates, open for depolarization, allow Na+ entry
27
H Gates
inactivation gates, prevent Na+ entry, closed by end of depolarization
28
5 Phases of Depolarization in Fast Response Fibers
1. Phase 0 2. Phase 1 3. Phase 2 4. Phase 3 5. Phase 4
29
Phase 0 of Depolarization in Fast Response Fibers
depolarization, rapid influx of Na+ ions, | Fast Na+ channels ## Footnote Tetrodotoxin poisons this channel
30
Phase 1 of Depolarization in Fast Response Fibers
Initial repolarization, partial efflux of K+ ions
31
Phase 2 of Depolarization in Fast Response Fibers
plateau phase, Slow Ca++ influx ## Footnote Ca++ influx is balanced by K+ efflux
32
Phase 3 of Depolarization in Fast Response Fibers
final repolarization, closure of Ca++ channels ## Footnote large efflux of K+
33
Phase 4 of Depolarization in Fast Response Fibers
stabilize resting membrane potential (Na+/K+ ATPase pump)
34
Effective Refractory Period
absolute refractory period
35
Slow Response Fibers
higher resting membrane potential (-70 to +10 mV), unstable membrane potential | no plateau on the depolarization curve ## Footnote slow depolarization "pacemaker tissue"
36
Phases of Depolarization in Slow Response Tissue
1. Phase 0 2. Phase 3 3. Phase 4
37
Phase 0 of Depolarization in Slow Response Tissue
action potential spike due to Ca++ influx, some K+ efflux ## Footnote Tetrodotoxin does not affect it, not steep, not fast Na+ channels,
38
Phase 3 of Depolarization in Slow Response Tissue
decrease in Ca++ influx, increase in K+ efflux ## Footnote repolarizes similar to other excitable tissue
39
Phase 4 of Depolarization in Slow Response Tissue
leaky channels, net effect -> Na+, Ca++ influx>K+ efflux, leak to threshold | Na+/K+ ATPase Pump
40
Order of Electrical Flow in the Heart
1. SA Node or pacemaker 2. AV Node 3. Bundle of His 4. Right and Left Bundle Branches 5. Purkinje Fibers
41
SA Node
sinoatrial node, most irritable part of the heart
42
AV Node
atrioventricular node
43
3 Standard Bipolar Leads
RA, LA, LL
44
3 Augmented Unipolar Leads
AVR, AVL, AVF
45
Eintoven's Triangle
triangle around the heart formed by standard bipolar leads and augmented unipolar leads
46
P Wave
deerpolarization of the Atria
47
QRS Complex
depolarization of ventricles S marks closure of AV Valves | "Lub" sound
48
T Wave
repolarization of the ventricles, | "Dub" sound ## Footnote same deflection as QRS in most leads, opposite deflection or abnormal height is indicative of myocaridal damage
49
Mean QRS Complex
vector sum of bipolar leads or vector sum of unipolar leads ## Footnote defines a coordinate axis system
50
Finding the Mean QRS Complex
1. look for the most biphasic wave and its corresponding lead, mean QRS will be perpendicular to it 2. confirm mean QRS direction by looking at two surrounding leads in that SAME LEAD GROUP (either bipolar or unipolar) 3. mean QRS is their vector sum
51
"Normal" Mean QRS
-30 to 100 degrees ## Footnote 60 degrees average
52
Causes Mean QRS to Negative
Right Coronary Infarct Left Ventricular Hypertrophy Aortic Stenosis Atherosclerosis ## Footnote Left side gets bigger or right side gets smaller
53
Causes Mean QRS to Positive
Left Coronary Infarct Right Ventricular Hypertrophy Pulmonary Emoblus Pulmonary Contriction ## Footnote Left side gets smaller or right side gets bigger
54
Right Axis Deviation
mean QRS from +100 to +180
55
Left Axis Deviation
mean QRS from -30 to -90
56
1 large block on EKG chart paper
.20 seconds
57
1 small block on EKG paper
.04 seconds
58
Calculating Heart Rate Using an EKG
300 dovoded bu the number of large blocks between 2 "R"s ## Footnote or the # of Rs in 3 seconds times 20
59
Tachycardia
heart rate greater than 100 bpm
60
Bradycardia
heart rate less than 60 bpm
61
P-R interval
0.10-0.20 ## Footnote longer means heart block
62
QRS segment
0.10 seconds
62
S
closure of AV valves
62
Q-T segment
0.40 seconds
62
Heart Blocks
Issue with SA to AV
63
1st Degree Heart Block
prolonged P-R interval (>0.20 seconds) | usually delay in the AV node
64
2nd Degree Mobitz Type 1(Wenchebach)
increasing PR interval, finally P wave does not produce QRS ## Footnote Longer, longer, longer, drop, now we have a Wenchebach
65
2nd Degree Mobitz Type 2
repeating P to QRS ratio of 2:1, 3:1, bradycardia | not all P waves produce QRS deflections ## Footnote usually problem with conducting through the bundle of His, Pacemaker for treatment
66
3rd Degree Heart Block
multiple P waves per QRS AND varying P-R interval, bradycardia | P waves do not evoke a QRS response, "Complete" Block ## Footnote slow, regular ventricular rhythm, pacemaker for treatment
67
Paroxysmal Tachycardia
abrupt onset and termination of rapid electrical(contractile) events
68
Supraventricular Tachycardia
normal QRS except high rate, recurrent AV junction impulse
69
Ventricular Tachycardia
huge and wide QRS complexes, aberrant impulse conduction within ventricle | Treat with IV Adenosine, Paced Shock, Vagal Manuevers, Pericardial Thump ## Footnote Very Dangerous!! Often leads to Ventricular Fibrillation
70
Fibrillation
unsynchronized, rippling contractoins
71
Atrial Fibrillation
not immedietly life threatening, blood pooling and subsequent clotting is biggest risk
72
Ventricular Fibrillation
nearly immediate unconsciousness lack of cooridinated contraction | little blood pumped ## Footnote death unless defibrillation occurs
73
Coronary Infarct Indicators
multiple events, not visible from all leads, exaggerated Q wave, notched QRS complex, Elevated "ST segment" with "J Point", inverted T waves with respect to QRS ## Footnote shift of mean QRS
74
STEMI
ST Elevated Myocardial Infartion
75
Inverted T waves
Non-Stemi Myocardial infarction ## Footnote can be normal in small children depending on lead placement

Bio 472 (23 decks)

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