Which of the following does not occur during ventricular systole?

• A. Opening of the semilunar valves
• B. Closure of the atrioventricular valves
• C. Filling of the ventricles with blood
• D. Ejection of blood into the aorta and pulmonary artery

Answer: (C)

Verified step by step guidance

1. Understand the phases of the cardiac cycle: The cardiac cycle consists of two main phases, systole and diastole. Systole is the phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries.
2. Identify what happens during ventricular systole: During ventricular systole, the ventricles contract, leading to the closure of the atrioventricular (AV) valves (tricuspid and mitral valves) to prevent backflow into the atria.
3. Recognize the role of semilunar valves: As the ventricles contract, the pressure inside them rises, causing the semilunar valves (aortic and pulmonary valves) to open, allowing blood to be ejected into the aorta and pulmonary artery.
4. Determine what does not occur during ventricular systole: Filling of the ventricles with blood does not occur during ventricular systole. Instead, this occurs during diastole when the heart muscle relaxes, and the ventricles fill with blood from the atria.
5. Conclude the analysis: Based on the understanding of the cardiac cycle, the event that does not occur during ventricular systole is the filling of the ventricles with blood, as this is a characteristic of diastole.