Sinoatrial node also activates a potassium channel, which allows K to flow out of the cell, making the membrane potential more negative and slowing the pacemaker potential, therefore decreasing the rate of action potential production and therefore decreasing heart rate. A decrease in heart rate is known as negative chronotropy. The first cell to produce the action potential in the SA node isn’t always the same, this is known as pacemaker shift. In certain species of animals, for example, in dogs, a superior shift (i.e. the cell that produces the fastest action potential in the SA node is higher than previously) usually
Orbital node terms αναβιβάζων and καταβιβάζων were also used for the ascending and descending nodes, giving rise to the English words "anabibazon" and "catabibazon". For the orbit of the Moon around Earth, the plane is taken to be the ecliptic, not the equatorial plane. The gravitational pull of the Sun upon the Moon causes its nodes to gradually precess westward, completing a cycle in approximately 18.6 years. Orbital node An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined. A non-inclined orbit, which is contained in the reference plane, has