Electrical Conduction System

What is the Sinoatrial Node (SA)?

Starts electrical impulse and triggers atrial contraction. 60-100 bpm

• main pacemaker

Which node is known as the main pacemaker?

Sinoatrial Node (SA)

What is Bachmann Bundle?

Sends signal from SA node to the Left atrium

What is the Internodal Pathways?

Consists of the anterior, middle, and posterior pathways that signal from SA node to the AV node

What is the Atrioventricular Node (AV node)?

Delays signal from Sa node and allows atria contract to fill ventricles

• secondary pacemaker; 40-60 bpm

What is the only route between the atria and ventricles?

Bundle of His

The right bundle of his branch sends signals to the ____ ventricle and the left bundle branch sends signals to the ____ ventricle

right, left

Which node is known as the secondary pacemaker?

Atrioventricular Node (AV)

What is known as the last-ditch pacemaker?

Purkinje FIbers

What are the functions of purkinje fibers

Initiates depolarization within muscle cells for contraction

• connects with myocytes, 20-40 bpm

What is the order of the cardiac conduction system?

1. SA Node (primary pacemaker)

2. AV Node (secondary pacemaker)

3. Bundle of His and Bundle Branches

4. Purkinje Fibers (last-ditch pacemaker)

In a ECG, where does the heart rhythm begin?

In the Sinoatrial Node and leads to atrial depolarization

What does the P wave represent?

Atrial Depolarization (contraction)

• first phase of the cardiac cycle

What does the QRS wave represent?

Ventricular Depolarization (contraction)

What does the T wave represent?

Ventricular Repolarization (relaxation)

Where does atrial repolarization occur in a ECG?

QRS complex

What is PR Interval?

Beginning or atrial depolarization to the beginning of ventricular depolarization

What is the ST segment?

Period in which the ventricle is completely depolarized

What does the QT interval represent?

Entire action potential