Understanding Cardiac Electrical Activity

These flashcards cover essential terms and concepts related to cardiac electrical activity and heart rhythm.

Electrical activity in the heart

The electrical signals that trigger heart contractions, beginning with the SA node and involving depolarization and repolarization of the atria and ventricles.

SA node

The sinoatrial node, which initiates the electrical impulses that control heart rhythm.

AV node

The atrioventricular node, which delays the electrical signal from the SA node to allow ventricles to fill.

Depolarization

The process by which heart muscle cells become more positively charged, leading to contraction.

Repolarization

The recovery phase for heart muscle cells when they return to their resting state after contraction.

QRS complex

The graphical depiction on an ECG representing ventricular depolarization.

T wave

The graphical representation of ventricular repolarization on an ECG.

Bradycardia

A heart rate that is slower than normal, typically below 60 beats per minute.

Tachycardia

A heart rate that is faster than normal, typically above 100 beats per minute.

Atrial fibrillation

An irregular, often rapid heart rate that results from chaotic electrical signals in the atria.

First degree heart block

A type of AV block where electrical signals are delayed but still reach the ventricles.