Heart 11

1
Heart (11) contraction
Myocardial contractile cells functional
syncytium RMP -90 mV
Na influx
Voltage regulated Na channels open
contraction
Slow Ca channels in sarcolemma (Ca influx)
Ca channels in SR
2
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3
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4
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5
Heart (12) contraction
Myocardial autorhythmic cells
Fast Ca channels in sarcolemma (Ca influx)
Na influx
depolarization
6
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7
Heart (13) contraction
Myocardial autorhythmic cells
SinoAtrial node
AtrioVentricular node
AV bundle (of His)
Purkinje fibers
Bundle branches
8
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9
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10
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11
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12
Lead I
0O
R
S
Q
S
Q

-
R
13
Lead II
60O
-
R
S
Q
Q
S
R

14
Lead III
-
120O
Q
R
S
S
Q
R

15
Lead aVR
-150O

S
Q
S
Q
R
R
-
16
Lead aVL
-30O
R
S

S
Q
Q
R
-
17
-
Lead aVF
90O
R
Q
S
S
Q
R

18
Lead III
-
120O
Q
R
S
S
Q
R
Mean electrical axis 120-90 30o

19
Heart Cardiac cycle
Diastole relaxation/filling Systole
contraction/ejection
20
ECG
ECG
Aorta
Lt. Ventricle
Lt. Atrium
Ventricular volume
21
EDV
SV
ESV
22
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