Which of the Following is Responsible for the Opening and Closing

Question

Which of the following is responsible for the opening and closing of the heart valves?
A) Pressure exerted on the valves as the heart contracts and relaxes
B) Electrical signals arising in the SA node
C) The degree of oxygen concentration of blood in the ventricles
D) The amount of blood in the heart

Accepted Answer

The opening and closing of heart valves is due to the pressure exerted on them as the heart contracts and relaxes. The pressure difference forces the valves to open and close, ensuring one-way blood flow through the heart. Electrical signals in the SA node initiate the heartbeat, but they are not responsible for opening and closing the valves. The degree of oxygen concentration in the blood and the amount of blood in the heart do not directly affect the opening and closing of valves.