Parasympathetic nervous system a healthy heart, the main pacemaker is a collection of cells on the border of the atria and vena cava called the sinoatrial node. Heart cells exhibit automaticity which is the ability to generate electrical activity independent of external stimulation. As a result, the cells of the node spontaneously generate electrical activity that is subsequently conducted throughout the heart, resulting in a regular heart rate. In absence of any external stimuli, sinoatrial pacing contributes to maintain the heart rate in the range of 60-100 beats per minute (bpm). At the same time, the two branches of the autonomic nervous system
Node (circuits) Dots used to mark nodes on a circuit diagram are sometimes referred to as "meatballs". Node (circuits) In electrical engineering, a node is any point on a circuit where the terminals of two or more circuit elements meet. In circuit diagrams, connections are ideal wires with zero resistance, so a node may consist of the entire section of wire between elements, not just a single point. According to Ohm's law, "V = IR", the voltage across any two points of a node with negligible resistance is showing that the voltage at every point of a node is the same. However,