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CV Final > Action Potential/ECG > Flashcards

Action Potential/ECG Flashcards

(59 cards)

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1
Q

hierarchy of conduction system

A

SA node - 60-80

AV node - 30-40

Purkinje - 20-30

Ventricular muscle - slowest

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2
Q

E-C coupling in the heart

A

AP - triggers Ca release - responsible for contraction

coupling! not same signal

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3
Q

Slow AP Conduction Tissues

A

SA Node

AV Node

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4
Q

I(k1)

A

highly expressed in most myocytes except the node!

keeps resting potential at about -80

basis of resting membrane potential in cell

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5
Q

Fast response action potential

A

Atrial, Purkinje, Ventricular Action Potentials

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6
Q

Phase 0

Fast response

A

Upstroke

Sodium is entering - I(Na)

I(K1) is closed - resting potential, close because Mg in the cell is trying to leave and it plugs the channel

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7
Q

Phase 1

Fast response

A

Early repolarization

I(to) - channel opens when in depolarized range and opens just for a short time

outward K+ current

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8
Q

Phase 2

Fast Response

A

Plateau

I(to) inactivated

I(k) - delayed rectifier! open and potassium leaves

I(ca) - trigger Ca - L type channels - voltage gated

plateau - balance of K out and Ca in

when inactivate I(Ca), delayed rectifier WINS and repolarization happens because K leaves

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9
Q

Phase 3

Fast Response

A

Final repolarization

I(k) [delayed rectifier] and I(k1) [resting current] both open and both letting out K!

back to rest

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10
Q

Phase 4

Fast response

A

Rest

I(K1) open - keeping resting potential

Na/K transporter working

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11
Q

Structure of Voltage gated K+ channel

A

4 separate subunits form channel

voltage sensor

Pore region

N-terminal - V-dependent inactivation

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12
Q

voltage sensor of K channel

A

S4

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13
Q

Pore region of votage gated K channel

A

S4-S5 linker

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14
Q

Voltage gated Na/Ca channel

A

same structure as K channel but single subunit has 4 repeats

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15
Q

I(K1)

A

inward rectifier current

resting membrane potential

outward current during phase 3

NOT voltage gated

closes at DEPOLARIZED membrane potentials

NOT in pacemaker cells

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16
Q

I(K)

A

delayed rectifier current

Outward current during phase 2 and 3

2 components:R and S

EXIST in pacemaker cells

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17
Q

Phase 0

Slow response

A

upstroke due to inward Ca current (L type Ca current

resting potential was already less negative (there is no I(K1))

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18
Q

Phase 3

Slow response

A
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19
Q

Phase 4

Slow response

A

slow diastolic depolarization

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20
Q

I(f)

A

current that contributes to phase 4 diastolic depolarization

inward Na+

induced by hyperpolarization and allows to oscillate toward depolarization

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21
Q

currents that contribute to diastolic depolarization in nodal cells

A

I(f) - inward Na - induced by hyperpolarization

I(ca) - inward Calcium

I(k) - outward delayed rectifier current (R and S

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22
Q

factors that influence pacemaker rate

A

slope of diastolic depolarization

threshold potntial

min diastolic potential

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23
Q

effect of parasympathetic stimulation

A

Activate I(k)ACH channels

lowers minimum diastolic potential

decreases slope of phase 4

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24
Q

effect of sympathetic stimulation

Study These Flashcards
A

activate I(f) channels

Increases slope of phaes 4

no change in min diastolic potential

25
unipolar limb leads
aVR, aVL, aVF Wilson's Central Terminal - average the other two! impossimble to flip
26
bipolar limb leads
I (right arm to left arm) II (right arm to left leg) III (left arm to left leg) possible to flip - true + and true -
27
precordial leads
V1-V6
28
lead diagram
29
augmented lead
aVR, aVL, aVF averaged vector
30
ventricle depolarization and ECG
starts on left side of septum moving toward right
31
Normal value of PR
.12-.2 seconds (less than 1 big box)
32
Normal QRS duration
.06-.10 seconds (less than half of a box
33
Normal QT interval duration
less than .44 in men and .46 in women (less than 2 boxes\_
34
time on EKG
1 big box is .2 sec, 200 msec 1 small box is .04 sec, 40 msec
35
voltage on ECG
1 big box = .5 mV
36
Count off method for HR
300-150-100-75-60-50 from QRS to QRS
37
left axis deviation
inferior wall MI left anterior fasciuclar block LVH -30 to -90 if up in I and down in II
38
right axis deviation
RVH acute R heart strain (PE) left posterior fascicular block +90-+180 down in 1 and up in 2
39
normal axis
up in limb I and limb II mean axis must fall between -30 and +90
40
RA enlargement on EKG
P wave lead II - higher at neginning V1 - biphasic
41
LA enlargement
P wave Lead II - higher at end V1 - p wave is negative!
42
Sign of RVH
R\>S in lead V1 R axis deviation
43
LVH
S in V1 + R in V5 R in aVL\>11 mm or R in I \>15 mm
44
ECG Read Order
1. rate 2. rhythm 3. axis 4. intervals (PR, QRS, QT) 5. Morphology - P, T, ST
45
RBBB
RSR' in V1 (rabbit ears) LV first (down in V1, Up in V6) Widneed QRS Prminent S in V5
46
LBBB
Early R added to big, late L and compound deeply negative in V1 rS Widened QRS broad, notched R in V6 absent R and prominent S in V1
47
RBBB contraction pattern
starts on R side of septum toward R big toward L then to R
48
LBBB contraction pattern
starts on right side of septum depol R then big swing to L
49
Left Anterior Fasicular block
Posterior to Anterior L axis deviation Small Q in aVL and I (first depolarization is away) Small R in inferior leads (II, III, aVF) - inital downward
50
Left posterior fasicular black
start anterior and swing posterior R axis deviation small R in aVL and I Small Q in inferior leads (II,III, aVF)
51
ST Elevation
ischemia acute-hours
52
Q wave
with ischemia begins hours after ischemia and deepens persists long after MI
53
T Wave Inversion
Days after ischemia will normalize
54
Pathologic Q Wave
fibrotic/bad conduction system - can't gt through (physical block) eventually jumps over it 25% QRS amplitude if seen in V1-V3
55
Hyperkalemia on EKG
Tall, peaked T wave
56
anteroseptal leads
V1, V2
57
anterolateral leads
V5, V6 I aVL
58
anteroapical leads
V3, V4
59
Inferior Leads
II, III, aVF

CV Final (6 decks)

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