Which of the following is/are true concerning the opening and closing of the cardiac valves? A. valves operate according to the pressures on either side of the valve B. valve operation is constantly...

Extracted text: Which of the following is/are true concerning the opening and closing of the cardiac valves? A. valves operate according to the pressures on either side of the valve B. valve operation is constantly being controlled by the medulla oblongata C. valve operation is determined directly by the cardiac action potential (electrical currents control the opening and closing of the valves.) D. valve operation is directly controlled by the papillary muscles within the ventricular wall. E. None of the above is correct.