The cardiac conduction system
is a group of specialized cardiac muscle cells
in the walls of the heart that send signals to
the heart muscle causing it to contract. The
main components of the cardiac conduction system
are the SA node, AV node, bundle of HIS, bundle
branches, and Purkinje fibers. The SA node (anatomical
pacemaker) starts the sequence by causing the
atrial muscles to contract. From there, the signal
travels to the AV node, through the bundle of
HIS, down the bundle branches, and through the
Purkinje fibers, causing the ventricles to contract.
This signal creates an electrical current that
can be seen on a graph called an Electrocardiogram
(EKG or ECG). Doctors use an EKG to monitor the
cardiac conduction system’s electrical
activity in the heart.
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