Cardiac action potential that originates from the sinoatrial node is propagated via the His-Purkinje network, the fastest conduction pathway within the heart. The electrical signal travels from the sinoatrial node (SAN), which stimulates the atria to contract, to the atrioventricular node (AVN) which slows down conduction of the action potential, from the atria to the ventricles. This delay allows the ventricles to fully fill with blood before contraction. The signal then passes down through a bundle of fibres called the bundle of His, located between the ventricles, and then to the purkinje fibers at the bottom (apex) of the heart, causing ventricular contraction.
Longitude of the ascending node Longitude of the ascending node The longitude of the ascending node (☊ or Ω) is one of the orbital elements used to specify the orbit of an object in space. It is the angle from a reference direction, called the "origin of longitude", to the direction of the ascending node, measured in a reference plane. The ascending node is the point where the orbit of the object passes through the plane of reference, as seen in the adjacent image. Commonly used reference planes and origins of longitude include: In the case of a binary star known only from visual observations,