Sinoatrial node action potentials, so that it can pass throughout the heart and cause contraction. An action potential is a change in voltage (membrane potential) across the membrane of the cell, produced by the movement of charged atoms (ions). Non-pacemaker cells (including the ventricular and atrial cells) have a period, immediately after an action potential, where the membrane potential remains relatively constant; this is known as a resting membrane potential. This resting phase (see cardiac action potential, phase 4) ends when another action potential reaches the cell. This produces a positive change in membrane potential (known as depolarisation), which initiates the start
Node (physics) the ratio of the amplitude of the wave at the antinode to the amplitude at the node. In resonance of a two dimensional surface or membrane, such as a drumhead or vibrating metal plate, the nodes become nodal lines, lines on the surface where the surface is motionless, dividing the surface into separate regions vibrating with opposite phase. These can be made visible by sprinkling sand on the surface, and the intricate patterns of lines resulting are called Chladni figures. In transmission lines a voltage node is a current antinode, and a voltage antinode is a current node. Nodes are