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
Lunar node Lunar node A lunar node is either of the two orbital nodes of the Moon, that is, the two points at which the orbit of the Moon intersects the ecliptic. The "ascending" (or "north") node is where the Moon moves into the northern ecliptic hemisphere, while the "descending" (or "south") node is where the Moon enters the southern ecliptic hemisphere. A lunar eclipse can occur only when the full Moon is near (within 11° 38' ecliptic longitude) either lunar node, while a solar eclipse can occur only when the new Moon is near (within 17° 25') either lunar node. Because