Annual deaths from tornadoes, earthquakes and floods together total fewer than 200. The most deadly heat wave in recent years occurred in Chicago over a week in July 1995, when temperatures hovered around 100 degrees.
Cardiac Cycle: 1st Systole Phase. During the systole phase, the right ventricle receives impulses from the Purkinje fibers and contracts. The atrioventricular valves close and the semilunar valves open. The de-oxygenated blood is pumped into the pulmonary artery.
Â§ events during systole: Â§ at the beginning of systole Ã  ventricular contraction occurs â A-V valves close , pressure begins to build up in the ventricles â no outflow of blood occurs during the first 0.2-0.3 seconds of ventricular contraction Ã  isovolumic contraction Â§ left ventricular pressure exceeds the aortic pressure of 80mm Hg â right ...