Physiological Basis of ECG part 1 Flashcards
When the SA nodes causes atria to depolarize from right to left this creates what part of the ECG?
P wave
When the AV node delays signal this creates what part of the ECG?
PR Interval
When the ventricles depolarize generally from right to left, form apex to base, from interior to exterior this creates what part of the ECG?
QRS complex
When the AP phase 2 delayed repolarization of ventricles this creates what part of the ECG?
ST segment
When the ventricles repolarize generally from left to right, base to apex this creates what part of the ECG?
T wave
The p wave represents what phase of AP in atrial muscle?
Phase 0
At the end of P wave and at the ST segment, all cells are?
Depolarized
The QRS complex represents what phase of AP in ventricular muscle?
Phase 0
The T wave represents what phase of AP in ventricular muscle?
Phase 3
How long is the PR interval?
It should not be longer than?
1) 0.16 s
2) 0.2 s
How long is the QT interval?
0.35 ms
What is the trick to approximating HR on an ECG?
Start at QRS complex and count the boxes to the next QRS complex and start from 300, 150, 100, 75, 60, 50
Where is the placement for lead 1?
Lead 2?
Lead 3?
1) RA to LA
2) RA to LL
3) LA to LL
The augmented vector, foot lead (aVF), is placed?
aVR?
aVL?
1) RA+LA to LL
2) LL+LA to RA
3) LL+RA to LA
V1 and V2 are mainly?
V4, V5, V6 are mainly?
1) Negative
2) Positive
The mean electrical axis is the average direction of spreading AP in ventricles, where does it use the average amplitude of QRS?
Leads 1 and aVF
On a mean electrical axis, when going from right to left lead I is?
When going from left to right?
1) Positive
2) Negative
On a mean electrical axis, when going from top to bottom the aVF lead is?
When going from bottom to top?
1) Positive
2) Negative
On a mean electrical axis, when both leads I and aVF are positive then there is?
If only lead I is negative?
If only aVF lead is negative?
1) Normal mean electrical axis
2) Right axis deviation
3) Left axis deviation
Right axis deviation usually is present with?
Left axis deviation?
1) Right ventricular hypertrophy
2) Left ventricular hypertrophy
Atrial repolarization occurs during?
QRS complex
What is the state of the atrial myocytes at the peak of the T wave?
Ventricular myocytes?
1) Fully replarized
2) Partially repolarized
When is the calcium influx greatest for atrial myocytes?
PR interval
There are three pacemaker nodes within the heart, what are the bpm for:
SA node?
AV node?
Purkinje fibers?
1) 60-100
2) 40-60
3) 15-40
