Week One Flashcards
automaticity
electrical signals generated by pacemaker cells
pacemaker cells can generate stimulus without outside stimulation
Cardiac Cycle
Electrical (caused by automaticity)
mechanical (muscular) (contraction)
Electrical Activity
depolarization
repolarization
mechanical responses
systole
diastole
depolarization = ______ = contraction
systole
repolarization= ______ = resting or filing phase
diastole
Depolarization begins with?
SA node firing
atrial contraction and atrial kick
SA node beats?
60-100 bpm
AV node beats
40-60 bpm
Ventricles (purkinje fibers) beats?
15-40 bpm
What can the ECG tell us?
orientation of the heart in the chest
conduction disturbances
electrical effects of medication and electrolytes
mass of cardiac muscles
presence of ischemic damage
ELECTRICAL (not mechanical -contraction)
lead 1
records flow from right to left arm
lead 2
Records flow from right arm to left leg
lead 3
records flow from left arm to left leg
augmented limb leads
unipolar center of heart to lead
aVR
from heart to right arm
aVL
heart to left arm
aVF
heart to left foot
lead 2,3, aVF see what part of the heart?
inferior heart
V1 and V2 see?
septal (mid heart)
V3 and V4 see?
anterior heart
1, aVL, V5 and V6 see?
lateral heart
one small ecg square is how many seconds?
0.04 s
how many small squares make up a large square?
5
how many seconds is a large square?
0.20 s
P wave
atrial depolarization (SA node is firing)
normal P wave
round, upright, before every QRS complex, all look the same
QRS complex
ventricular depolarization
Q wave
less than 0.04 s
less than 1/3 the height of the R wave
PR interval
beginning of P wave to beginning of QRS complex
0.12- 0.20 sec (3-5 small blocks)