During atrial systole, which valve is open?

Step-by-step solution

Ventricular systole increases the ventricular pressure causing the closure of tricuspid and bicuspid valves due to attempted backflow of blood into the atria. As the ventricular pressure increases further, the semilunar valves guarding the pulmonary artery (right side) and the aorta (left side) are forced open, allowing the blood in the ventricles to flow through these vessels into the circulatory pathways . The ventricles now relax (ventricular diastole) and the ventricular pressure falls causing the closure of se