During isovolumetric ventricular contraction, what happens to ventricular volume?

• A. It increases.
• B. It decreases.
• C. It remains constant.
• D. It fluctuates.

Answer: (C)

During isovolumetric ventricular contraction, the ventricle builds pressure while all valves are closed. Since both the atrioventricular valves and the semilunar valves are shut, no blood can enter or exit the ventricle, so its volume stays the same. The term isovolumetric reflects this constant-volume state. Once the ventricular pressure rises above the pressure in the aorta or pulmonary artery, the semilunar valves open and ejection begins, and the volume then decreases. So the correct idea is that ventricular volume remains constant during this phase.