What would happen if there were no valves between the atria and ventricles?
The valves prevent backflow from the ventricles into the atria when the ventricles contract, so without them, the blood would rush back into the atria.
What prevents the AV valves from opening back into the atria?
As the ventricles begin to contract, they force the AV valves to close, which in turn pull on the chordae tendineae. The chordae tendineae pull on the papillary muscles. The papillary muscles respond by contracting, opposing the force that is pushing the valves toward the atria.
