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.
Systole: A period of contraction called systole. Phases of Cardiac Cycle: It can be divided into four distinct phases: (I) Contraction Phase and (Ii) Ejection Phase, Both Occurring In Systole; (Iii) Relaxation Phase and (Iv) Filling Phase, Both Occurring In Diastole.