Which term describes ventricular contraction?

• A. Diastole
• B. Atrial systole
• C. Systole
• D. Diastolic filling

Answer: (C)

Ventricular contraction is systole. During the cardiac cycle, systole is the phase when the ventricles contract to generate pressure strong enough to eject blood into the pulmonary artery and aorta. This follows ventricular depolarization on the ECG (the QRS complex). In contrast, diastole is when the ventricles relax and fill, atrial systole is the contraction of the atria, and diastolic filling refers to ventricular filling during diastole.