They make up the cardiac pacemaker, that is, the natural pacemaker of the heart. In most humans, the concentration of pacemaker cells in the sinoatrial (SA) node is the natural pacemaker, and the resultant rhythm is a sinus rhythm. Sometimes an ectopic pacemaker sets the pace, if the SA node is damaged or if the electrical conduction system of the heart has problems.
Use IE Tab for Chrome. The best way to use Java (or Silverlight, or other NPAPI-based technologies) going forward is to use IE Tab for Chrome. You can set up Auto URLs to automatically open certain urls using IE Tab, providing a seamless experience, as if Java support never went away. Get it here:
Java and Google Chrome Browser. Chrome no longer supports NPAPI (technology required for Java applets) The Java plug-in for web browsers relies on the cross platform plugin architecture NPAPI, which has been supported by all major web browsers for over a decade. Google's Chrome version 45 (scheduled for release in September 2015) drops support for NPAPI, impacting plugins for Silverlight, Java, Facebook Video and other similar NPAPI based plugins.