Sinoatrial node therefore cause ischaemia and cell death in the SA node. This can disrupt the electrical pacemaker function of the SA node, and can result in sick sinus syndrome. If the SA node does not function, or the impulse generated in the SA node is blocked before it travels down the electrical conduction system, a group of cells further down the heart will become its pacemaker. The sinoatrial node was first discovered by a young medical student, Martin Flack, in the heart of a mole, whilst his mentor, Sir Arthur Keith, was on a bicycle ride with his wife. They made
Lunar node about 0.94901 Gregorian year, as do descending-node eclipses. The nodes are called by different names in different areas of the world. In ancient European texts, the ascending node is referred to as the dragon's head ("Caput Draconis", or "Anabibazon"). Its symbol is , the astronomical and astrological symbol for the dragon's head. By the same analogy, the descending node is also known as the dragon's tail ("Cauda Draconis", or "Catabibazon"), and its symbol is the inversion of that of the ascending node: . In Hindu astronomy, the ascending node ☊ is called "Rahu" and the descending node ☋ is called