Electrical System – Heart

The rhythmic contraction of the heart, the heart beat, although regulated by the sinoatrial node (or SA node) of the heart is the result of both the sinoatrial node and the atrioventricular node (AV node) of the heart.

As mentioned in previously, the heart’s electrical system or the cardiac conduction system, is comprised of the SA node and AV node.  However, these 2 main components are not the only parts that are responsible for the heart’s regular functioning as a pump.  

Cells:

There are 2 type of cells that assist in the heart pumping:

• Conducting or cardiac cells that generate and conduct an electric current
• Smooth Muscle cells that contract upon receiving an electric signal

Path and Order of Electrical Impulses:

1. Sinoatrial Node
2. Atrioventricular Node
3. Bundle of His
4. Right and Left bundle branches
5. Purkinje fibers

Sinoatrial Node (SA node):

• Referred to as the pacemaker of the heart
• Sets the rhythm and rate of the heart
• Generates electrical signals that 2 things:
• Cause the right and left atrium to contract pushing blood into the right and left ventricles
  • Pass electrical signal to the atrioventricular node
• Located near the top of the right atrium
• Impacted by the ANS (autonomic nervous system) and PNS (parasympathetic nervous system)
• Impacted by hormones