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.
I know that during ventricular diastole the cuspid valves are open and the semilunar valves are closed. And during ventricular systole the cuspid valves close and semilunar valves are open. BUT atrial systole and diastole is sooo confusing :S. Please someone explain.