Wolff–Parkinson–White syndrome cardiac action potential arises in the sinoatrial (SA) node, which is located in the right atrium. From there, the electrical stimulus is transmitted via internodal pathways to the atrioventricular (AV) node. After a brief delay at the AV node, the stimulus travels through the bundle of His to the left and right bundle branches and then to the Purkinje fibers and the endocardium at the apex of the heart, then finally to the ventricular myocardium. The AV node serves an important function as a "gatekeeper", limiting the electrical activity that reaches the ventricles. In situations where the atria generate excessively
Orbital node Orbital node An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined. A non-inclined orbit, which is contained in the reference plane, has no nodes. Common planes of reference include the following: If a reference direction from one side of the plane of reference to the other is defined, the two nodes can be distinguished. For geocentric and heliocentric orbits, the ascending node (or north node) is where the orbiting object moves north through the plane of reference, and the descending node (or south node) is where it