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What is During the Ventricular Systole, atrioventricular valves open, semilunar valves close. The statement is and explain in detail?
During ventricular systole, contraction of the ventricles causes pressure in the ventricle to increase. 
Almost immediately the AV valves close (the first heart sound). The pressure in the ventricle continues to increase. 
Continued ventricular contraction causes the pressure in the ventricle to exceed in the pulmonary trunk and aorta. As a result, the semilunar are forced open and blood is ejected into the pulmonary trunk and aorta.