ECG Demonstration

Anatomy

What is the resting state of a cardiomyocyte?

Polarized

What does polarized mean?

There is a charge differential across the cell membrane

What is the resting membrane potential of a polarized cardiomyocyte?

Voltage -70mV

What allows the cell to achieve polarization?

Sodium and Potassium pumps turn on

What causes depolarization? What is it?

Opening of sodium channels, flipping of the voltage differential across the cell membrane

What is the voltage of a depolarized cell?

+40

What is a synonym for depolarization?

Action potential

What initiates a heart beat on the ECG?

SA Node

What happens during the P Wave?

Depolarization of both atria

What happens during the PR Interval?

AV nodal pause

What is the QRS complex?

Purkinje fibers depolarize

What results from the Purkinje Depolarizaiton

Contraction of both ventricles

What is the ST segment?

Repolarization of both ventricles

What happens during ventricular repolarization?

Ventricle cells become polarized

What is Q on T

Initiation of depolarization during the ST segment

What is the significance of Q on T

It can create idio-ventricular rhythms

What 2 ventricular rhythms come from Q on T

ventricular tachycardia and fibrillation