What causes the opening and closing of heart valves? Contraction of the papillary muscles of the ventricles Changes in the shape of the fibrous skeleton Changes in the oxygen content of the blood Changes in blood pressure across the valves
What causes the opening and closing of heart valves? Contraction of the papillary muscles of the ventricles Changes in the shape of the fibrous skeleton Changes in the oxygen content of the blood Changes in blood pressure across the valves