Electrical Conduction
What structure normally starts the electrical impulse of the heart?
SA Node
What does the P wave represent?
Atrial depolarization
What does the QRS complex represent?
Ventricular depolarization
Ventricular repolarization
What does the PR interval measure?
The start of atrial depolarization to the start of ventricular depolarization
Put these in the correct order.
AV Node -> Purkinje Fibers -> SA Node -> Bundle of HIS -> Bundle Branches
SA Node -> AV Node -> Bundle of HIS -> Bundle Branches -> Purkinje Fibers
Which chambers are electrically activated during the P wave?
The atria
Which happens first electrically: atrial or ventricular depolarization?
Atrial depolarization
What does the U wave represent?
Late repolarization of the ventricles
What structure(s) are involved in the delay represented by the PR interval?
AV node
Which electrolyte is abundant intracellular during depolarization?
Sodium
If you see a P wave before every QRS complex, what does that suggest about the rhythm?
The SA node is starting and sending the impulse down the atria and down for the ventricles to contract.
Why isn't atrial repolarization normally seen as a wave on an EKG?
It occurs at about the same time as ventricular depolarization.
Which comes first: ventricular depolarization or ventricular repolarization
Ventricular depolarization
What does the QT interval represent?
The time it takes for the ventricles to depolarize and then repolarize
Which structure takes over as the backup pacemaker if the SA Node stops functioning as the primary pacemaker?
AV Node
True or False: The P wave represents ventricular contraction.
Which parts of the electrical conduction system are responsible for ventricular depolarization?
Bundle of HIS, Bundle Branches, Purkinje Fibers
Put these in order:
T wave, P wave, QRS, U wave
P wave -> QRS -> T wave -> U wave
60 beats or less per minute
At what rate does the SA node fire at?
60-100 bpm
Describe how P waves might appear (think of the 3 examples covered in our notes)
Upright, inverted or biphasic
A normal QRS measures between _____ and _____
0.06-0.10
A QRS measuring greater than 0.12 indicates a potential _______________________
BBB - Bundle Branch Block
What is measured horizontally on an EKG?
Time