During the cardiac cycle, why do the aortic and pulmonic valves close after the ventricles relax?
◦ Papillary muscles relax, which allows the valves to close.
◦ Chordae tendineae contract, which pulls the valves closed.
◦ Reduced pressure in the ventricles creates a negative pressure, which pulls the valves closed.
◦ Blood fills the cusps of the valves and causes the edges to merge, closing the valves.