Saturday, 21 November 2009  Cardiac conduction system  To be
able to pump blood and circulate it around the body, the heart
will need to continuously generate electrical impulses. These
impulses are normally transmitted through the heart via the
cardiac conduction system, this causing the heart to contract a
beat.   Sinoatrial (SA) node This is located in the right atrium
where the superior vena cava joins the atrial tissue mass,
normally the SA node acts as the main pacemaker in the heart.
Under normal resting conditions, the SA node fires at 60 to 100
beats per minute.  Internodal tracts and Bachmann's bundle: 
From the SA node, the impulse travels through the right and left
atrium, the impulse, may be transmitted along 3 internodal
tracts:    • Anterior   • Wenckebach's   • Thorel's
Atrioventricular (AV) node. The atrioventricular (AV) node is
positioned between the coronary sinus and the tricuspid valve's
septal cusp, the AV node itself doesn't possess pacemaker cells,
but the surrounding junctional tiss