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Clin Med Cardio Exam 1 > Electrocardiography > Flashcards

Electrocardiography Flashcards

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1
Q

What is the #1 cause of death for males and females?

A

Cardiovascular disease

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2
Q

How many times does your heart beat/day? How many times/year?

A

100,000 daily

35 million yearly

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3
Q

How much does your heart weigh?

A

9-12 oz

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4
Q

How much of the chest cavity does the heart take up?

A

2/3 of the left sternal border

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5
Q

What provides the heart with its blood supply, oxygen, and nutrients?

A

Coronary arteries

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6
Q

Where do the coronary arteries originate?

A

Base of ascending aorta immediately above cusps of aortic valve

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7
Q

Does the heart receive blood during systole or diastole?

A

Diastole

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8
Q

Where is the myocardium most venerable to external forces?

A

Immediately to the left of the sternum, anterior side

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9
Q

supplies the SA node and the AV node

A

Right coronary artery

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10
Q

What happens when someone has an issue with their right coronary artery?

A

They’re going to have major electrophys changes due to the SA node and the AV node not having a good supply of blood

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11
Q

What feeds the lateral wall of the heart?

A

Left coronary

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12
Q

What feeds the inferior wall of the heart?

A

Right coronary

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13
Q

What wall is most concerning

to have an MI?

A

Anterior wall – one major concern over time – may eventually develop aneurism

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14
Q

99% of cardiac cells are?

A

Myocyte cells

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15
Q

Why are myocyte cells striated?

A

So they can contract

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16
Q

What is the purpose of gap junctions (intercalated discs)

in myocyte cells?

A

So that the impulse can jump from cell to cell

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17
Q

Myocyte cells are ______ controlled

A

Involuntarily

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18
Q

What is the other 1% of cardiac cells?

A

Pacemaker cells

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19
Q

What does it mean that pacemaker cells are autorythmic?

A

They can generate an AP on their own

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20
Q

Pacemaker cells are coupled to myocyte cells via?

A

Gap junctions

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21
Q

What is the resting membrane potential of a Pacemaker cell??

A

There isn’t one

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22
Q

What are the 3 types of pacemaker cells?

A

SA cells
AV cells
Purkinje cells

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23
Q

What is the last type of cardiac cell?

A

Specialized conducting cells

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24
Q

What is the pathway of an impulse through the heart?

A

SA node, Interatrial pathway, internodal pathway, AV node,

bundle of his, right and left bundle branches, Purkinje fibers

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25
Minimal change in polarity required to produce an action potential
Threshold
26
Change in electrical potential that occurs inside and outside the cell when stimulated
Action potential
27
The SA node and the AV node have a ______ response action potential
slow
28
How do the SA node and AV node keep from firing at the same time?
They have different resting potentials
29
The SA node has a _____ resting membrane potential than the AV node
Higher
30
What is phase 4 of the SA and AV node action potential?
Spontaneous depolarization (pacemaker potential) that triggers an AP once the threshold is met
31
What is the threshold of the SA and AV node?
between -40 and -30 mV
32
What is phase 0 of the SA and AV node action potential?
Depolarization phase
33
What is phase 3 of the SA and AV node action potential?
Replarization
34
When does a pacemaker cell completely depolarize?
-60mV
35
SA/AV: At -60mV (phase 4), what is influxing into the cell?
Na+
36
SA/AV: At -50mV (phase 4), what is influxing into the cell
Ca++
37
SA/AV: At phase 0 (depolarization), what is influxing into the cell?
Ca++
38
SA/AV: At phase 3 (repolarization), what is happening in the cell?
Outward flux of K+ and inactivated channels of Ca++
39
What is required for pacemaker channels to become activated?
A hyper polarized state
40
What is happening in phase 4 of the Purkinje fiber AP?
Slow Na+ leaked inward at -90mV (resting membrane potential)
41
What is happening at phase 0 of purkinje fiber action potential?
Fast Na+ entry (depolarization)
42
What is happening at phase 1 of purkinje fiber action potential?
Na+ channels inactivated
43
What is happening at phase 2 of purkinje fiber action potential?
Slow Ca++ entry and K+ exit
44
What is happening at phase 3 of purkinje fiber action potential?
Repolarization - Fast K+ exit
45
Pacemaker cells have ____ which means they don't need a neighboring cell to tell them to fire
Automaticity
46
Once a pacemaker cell reaches -60mV, what happens?
The cycle spontaneously happens again, which is why pacemaker cells are said to have "no resting membrane potential"
47
Can myocyte cells be autorhytymic?
NO!
48
Myocyte cells have a ____ response and a _____ resting membrane potential
Fast | True
49
Is there more sodium on the outside of the cell or the inside?
Outside
50
Is there more K+ on the outside of a cell or the inside?
Inside
51
What is the resting membrane potential of a myocyte? What Phase is RMP?
-90mV | Phase 4
52
What is the threshold for depolarization of a myocycte? What phase is depolarization?
-70mV | Phase 0
53
What phase is it in a myocyte cell when the Na+ channels close and K+ leaves the cell slowly?
Phase 1
54
What phase is it in a myocyte cell when Ca2+ enters the cell slowly and K+ leaves the cell?
Phase 2
55
What phase is it in a myocyte cell when K+ channels close and Na+ rapidly influxes?
Depolarization! Phase 0
56
What phase is it when all channels are closed, but K+ is exiting the cell?
Phase 4, RMP
57
What phase is it when the calcium channels close, and K+ leaves the cell rapidly?
Phase 3, repolarization
58
No stimulus no matter how strong will depolarize the cell
Absolute refractory period
59
A sufficiently strong simtulus will depolarize the myocardial cell
Relative refractory period
60
How many times does the SA node cell depolarize per minute?
60 to 100
61
How many times does the AV cell depolarize per minute?
40 to 60
62
How many times does the purkinje cell depolarize per minute?
20-40
63
Which side of the heart pumps more blood?
They both pump the same
64
Does conduction velocity occur faster in the LBB or the RBB?
LBB
65
What causes ventricular myocytes to depolarize?
Na+ entering the cell
66
Which wall is opposite the inferior wall?
Lateral wall
67
If the HR is 50bpm, which autorhythmic cell is likely the pacemaker of the heart?
AV node cell
68
The primary ion responsible for depolarization of the AV node?
Ca2+
69
How long does it take for specialized conduction to go from the SA node to the far side of the left atrium?
0.09 seconds
70
How long does it take for specialized conduction to go from the SA node to the AV node?
0.03 seconds
71
How long does it take for specialized conduction to go from the SA node to the bundle of his?
.16s
72
How long does it take for specialized conduction to go from the SA node to the purkinje fibers?
.19s
73
How long does it take for specialized conduction to go from the SA node to the epicardial wall?
.22s (1/5 of a second)
74
Sympathetic innervation of the heart is accomplished by the hormones __?
Epinephrine and norepinephrine
75
What types of receptors do epinephrine and norepinephrine bind to?
Adrenergic
76
When the sympathetic system acts on the heart, heart rate, conduction velocity, and force of contraction all ??
Increase
77
Parasymphathetic innervation of the heart is accomplished by the hormone
acetylcholine
78
acetylcholine binds to what type of receptors?
muscarinic
79
When he parasympathetic system acts on the heart, the heart rate and conduction velocity ?
Decrease
80
The inside of myocardial cells is more _____ charged in relationship to the outside where it is more ____ charged
``` Inside = negative Outside = positive ```
81
A wave of depolarization or repolarization travels from cell to cell via ___ ___
Gap junctions
82
Whenever there is a difference in charge inside or outside the cell, a ___ is formed
Vector
83
When a vector is formed, this creates a _____
Wave (ECG)
84
What is the flow of electricity through the heart?
``` SA node Atria AV node Bundle of his Purkinje fibers Ventricles ```

Clin Med Cardio Exam 1 (3 decks)

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