Heart Electrical System

What controls the rhythm of the heart?

SA Node sends electrical impulses that cause the heart muscle to contract.

What does the electrical conduction system do?

It coordinates the contraction of the atria and ventricles so blood pumps efficiently.

What is depolarization in the heart?

electrical activation of heart muscle cells that causes contraction.

Where does the heartbeat normally start?

The Sinoatrial (SA) node.

What heart rate does the SA node normally produce?

About 60-100 beats per minute.

What happens when the SA node fires?

Electrical signals spread across the atria causing atrial contraction.

How does the electrical signal spread from the SA node?

Through the atria and internodal pathways to the AV node.

What happens to the atria when the signal spreads?

The atria depolarize and contract, pushing blood into the ventricles.

What is the intrinsic rate of the AV node?

About 40-60 beats per minute.

What is the AV Bundle of His?

A pathway that carries the electrical signal from the AV node to the ventricles.

Where is the AV Bundle of His located?

In the interventricular septum.

What happens after the Bundle of His?

The signal splits into right and left bundle branches.

What do the bundle branches do?

They carry the electrical impulse toward the apex of the heart.

What are Purkinje fibers?

Specialized fibers that spread the electrical signal throughout the ventricles.

What happens when Purkinje fibers activate?

The ventricles contract and pump blood

What is the intrinsic rate of Purkinje fibers?

About 20-40 beats per minute.

What ECG wave represents atrial depolarization?

P wave

What ECG complex represents ventricular depolarization?

QRS complex

What ECG wave represents ventricular repolarization?

T wave

What is the correct order of the heart's electrical conduction?

S A A B B P

What is S A A B B P

SA node👉🏼

Atria👉🏼

AV node👉🏼

Bundle of His👉🏼

Bundle branches👉🏼

Purkinje fibers