Intro to EKGs Flashcards
What are the properties of cardiac cells?
Automaticity
Excitability
Conductivity
Contractility
What is automaticity
The ability to spontaneously initiate an impulse.
What is excitability
Results from ion shifts across the membrane and indicates how well a cell responds to an electrical stimulus.
What is conductivity
The ability of a cell to transmit an electrical impulse to another cell.
What is contractility
How well the cell contracts after depolarization/receiving a stimulus.
What is a normal duration for the QRS complex?
<0.11 seconds
What are the two phases of the QRS complex?
- ) depolarization of the inter ventricular septum from left to right.
- ) simultaneous depolarization of the right and left ventricles.
What is contained in the PR interval
The P wave and the PR segment
How long is a normal PR interval
0.12-0.20 seconds (not larger than one big box)
As heart rate increases, what happens to the PR interval and the QT interval
They shorten
What doe the PR interval represent?
The time between atrial depolarization and ventricular depolarization (the delay of the AV junction)
What is a normal duration for a QRS complex?
0.8 to 0.12 seconds
What is contained in the QT interval
the beginning of the QRS complex to the end of the T wave
What does the QT interval represent
the total ventricular activity (depolarization to depolarization)
What is the normal duration of the QT interval
0.44 to 0.46 seconds.
