What occurs during ventricular relaxation?

What occurs during ventricular relaxation?

• A. Decreased ventricular pressure causes AV valves to open and SL valves to close passively.
• B. AV valves close and SL valves open.
• C. Increased ventricular pressure causes SL valves to close.
• D. AV valves stay closed and SL valves stay closed.

Answer: (A)

During ventricular relaxation the ventricle’s pressure falls. This drop allows the atrioventricular valves (the ones between atria and ventricles) to open, so blood can flow passively from the atria into the ventricles. At the same time, the semilunar valves (the aortic and pulmonary valves) stay closed because the arterial pressures in the aorta and pulmonary artery are still higher than the ventricular pressure, preventing backflow. So the key idea is a fall in ventricular pressure enabling AV valve opening and SL valve closure, leading to passive ventricular filling.

During ventricular relaxation the ventricle’s pressure falls. This drop allows the atrioventricular valves (the ones between atria and ventricles) to open, so blood can flow passively from the atria into the ventricles. At the same time, the semilunar valves (the aortic and pulmonary valves) stay closed because the arterial pressures in the aorta and pulmonary artery are still higher than the ventricular pressure, preventing backflow. So the key idea is a fall in ventricular pressure enabling AV valve opening and SL valve closure, leading to passive ventricular filling.