Cardiac Conduction and Rhythm

Flashcards covering key concepts related to cardiac conduction and rhythms.

Internal Control

The electrical conduction system of the heart led by the pacemaker.

External Control

Influences heart rate, primarily through the cardiac centre of the brain.

Medulla Oblongata

Part of the brain that activates the parasympathetic and sympathetic systems.

Epinephrine and Norepinephrine

Hormones that increase heart rate.

Sinoatrial (SA) Node

Natural pacemaker of the heart with a firing rate of 60-100 bpm.

Atrioventricular (AV) Node

Delays electrical impulses, firing at 40-60 bpm.

Bundle of His

Conducts signals from the AV Node to the ventricles.

Purkinje Fibers

Spread electrical signals throughout the ventricles at 20-40 bpm.

Normal Sinus Rhythm

A regular rhythm of 60-100 bpm, with P waves before each QRS complex.

Sinus Bradycardia

A regular rhythm with a heart rate of less than 60 bpm.

Sinus Tachycardia

A regular rhythm with a heart rate greater than 100 bpm.

Atrial Fibrillation

An irregular rhythm with no clear P waves.

Atrial Flutter

Characterized by a 'sawtooth' pattern with multiple P waves.

Ventricular Tachycardia

Rapid heart rate with wide QRS complexes, may have a pulse.

Ventricular Fibrillation

Chaotic electrical activity with no organized contractions.

Asystole

Flatline, indicating no electrical activity in the heart.

Defibrillation

A process to restore normal rhythm; can shock Ventricular Tachycardia (if pulseless) and Ventricular Fibrillation.

Pulseless Electrical Activity (PEA)

Electrical activity present without heart contractions; cannot be defibrillated.