Cardiovascular System #3 (pg 1 - 2) - [6.28.17]
ECG has three waves. What are they?
1) P wave 2) QRS complex 3) T wave
List each wave of the ECG and which electrical event is associated with each
1) P-wave -> atrial depolarization 2) QRS complex -> ventricular depolarization and atrial repolarization 3) T-wave -> ventricular repolarization
Which chambers of the heart is the myocardium surrounding?
All of the chambers
The P wave of the ECG represents what?
Atrial depolarization
When we say electrical activity, which electrical events are we referring to?
Depolarization Repolarization
What does ECG stand for?
Electrocardiograph
When does atrial repolarization occur?
It also occurs during the QRS complex. It's masked by the ventricular depolarization in the QRS complex. Atrial repolarization happens at the same time as the ventricular depolarization.
What must follow depolarization?
Repolarization
When you record a person's ECG, what are you recording?
The electrical activity of the myocardium
What does atrial depolarization mean?
This means the myocardial cells around the atriums (atria) have depolarized and can now contract
What does ventricular depolarization mean?
This means the myocardial cells of the ventricles have depolarized and can now contract
What does ventricular repolarization mean?
This means the myocardial cells of the ventricles have repolarized and can now relax
Therefore, the QRS complex of the ECG represents what in all?
Ventricular depolaization AND atrial repolarization
The QRS complex of the ECG represents what?
Ventricular depolarization
Which is stronger - atrial repolarization or ventricular depolarization?
Ventricular depolarization is stronger The contraction of the ventricles is a stronger event than the relaxation of the atria
The T wave of the ECG represents what?
Ventricular repolarization
With an ECG, we can only record what?
When the myocardial is depolarizing and repolarizing
What electrical sequence is missing from the ECG?
atrial repolarization
