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
Blank node Blank node In RDF, a blank node (also called "bnode") is a node in an RDF graph representing a resource for which a URI or literal is not given. The resource represented by a blank node is also called an anonymous resource. According to the RDF standard a blank node can only be used as subject or object of an RDF triple. Blank nodes can be denoted through blank node identifiers in the following formats, RDF/XML, RDFa, Turtle, N3, N-Triples, and RDFa. The following example shows how it works in RDF/XML. The blank node identifiers are only limited in scope