Atrioventricular node the crista terminalis, and anteriorly, via the interatrial septum. Contraction of heart muscle cells requires depolarization and repolarization of their cell membranes. Movement of ions across cell membranes causes these events. The cardiac conduction system (and AV node part of it) coordinates myocyte mechanical activity. A wave of excitation spreads out from the sinoatrial node through the atria along specialized conduction channels. This activates the AV node. The atrioventricular node delays impulses by approximately 0.09s. This delay in the cardiac pulse is extremely important: It ensures that the atria have ejected their blood into the ventricles first before the ventricles
Lunar node about 0.94901 Gregorian year, as do descending-node eclipses. The nodes are called by different names in different areas of the world. In ancient European texts, the ascending node is referred to as the dragon's head ("Caput Draconis", or "Anabibazon"). Its symbol is , the astronomical and astrological symbol for the dragon's head. By the same analogy, the descending node is also known as the dragon's tail ("Cauda Draconis", or "Catabibazon"), and its symbol is the inversion of that of the ascending node: . In Hindu astronomy, the ascending node ☊ is called "Rahu" and the descending node ☋ is called