Final answer:
The cardiac cycle refers to the events taking place between the onset of atrial contraction and the end of ventricular relaxation, encompassing both systole and diastole to pump blood effectively.
Step-by-step explanation:
The cardiac cycle is all events associated with blood flow through the heart in one complete heartbeat. This sequence includes periods known as systole and diastole. The cardiac cycle starts with the atrial contraction, pumping blood into the ventricles, a phase called atrial systole. Following this, the ventricles contract during ventricular systole, ejecting blood into the systemic circuit. During ventricular systole, the heart's muscle contracts, pumping blood into circulation, while ventricular diastole is the period of relaxation as the chambers fill with blood.
Both the systolic and diastolic phases need to be carefully regulated for efficient blood flow. The coordination of these cycles ensures that the heart functions effectively, distributing oxygenated blood throughout the body and then refilling with deoxygenated blood from systemic circulation. During the cardiac cycle, the atria and ventricles work together to efficiently pump blood throughout the body.