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.
Diastole includes the contraction of the atria and the filling of the ventricles. The cardiac cycle breaks systole and diastole down into five phases during one heartbeat. It describes changes in pressure, volume, and flow through the heart in each phase.