Electrical conduction system of the heart Electrical conduction system of the heart The electrical conduction system of the heart transmits signals generated usually by the sinoatrial node to cause contraction of the heart muscle. The pacemaking signal generated in the sinoatrial node travels through the right atrium to the atrioventricular node, along the Bundle of His and through bundle branches to cause contraction of the heart muscle. This signal stimulates contraction first of the right and left atrium, and then the right and left ventricles. This process allows blood to be pumped throughout the body. The conduction system consists of specialised heart muscle cells, and is
Node 4 Node 4 Node 4, also known as the Docking Hub System (DHS), is a proposed module of the International Space Station (ISS). As of 2011 NASA was considering a 40-month design and development effort for Node 4 that would result in its launch in late 2013. Node 4 would be built using the Node Structural Test Article (STA) and docked to the forward port of the Harmony module. The Structural Test Article was built to facilitate testing of ISS hardware and was intended to become Node 1. However, during construction, structural design flaws were discovered. The under-construction Node 2 was