What event characterizes ventricular systole?

Ventricular systole is defined as the phase of the cardiac cycle where the ventricles contract and pump blood into the large arteries. During this phase, the pressure within the ventricles rises, leading to the opening of the aortic and pulmonary valves. This allows for the ejection of blood into the aorta and the pulmonary arteries, effectively delivering oxygenated blood to the body and deoxygenated blood to the lungs for re-oxygenation.

The option that indicates blood is pumped into the pulmonary arteries highlights the critical action of the right ventricle during this phase, as it is responsible for sending deoxygenated blood to the lungs. Although this point is relevant, it's not wholly encompassing of the entirety of ventricular systole, which involves the pumping of blood from both ventricles into their respective arteries.

The focus on ventricular contraction clearly identifies the primary function occurring during this time, distinguishing it from the other options that either describe filling action or activities related to a different phase of the cardiac cycle. For instance, the filling of the heart with blood occurs during diastole, not systole, and the contraction of the atria and filling of the ventricles happen just before ventricular systole, thus reinforcing that the primary action of ventricular syst