What are the two phases of the cardiac cycle?

The two phases of the cardiac cycle are indeed systole and diastole. Systole refers to the phase of the cardiac cycle when the heart muscles contract, pumping blood out of the chambers and into the arteries. This phase is crucial for circulating oxygen-rich blood to the body. Diastole, on the other hand, is the phase when the heart muscles relax, allowing the chambers to fill with blood. This process is essential for ensuring that there is enough blood available for the next contraction. Together, these two phases account for the rhythmic beating of the heart and are vital for maintaining effective blood circulation throughout the body.

Other options, while they may suggest processes related to the heart or body functions, do not encompass the specific cyclic phases that directly relate to the action of the heart in the context of blood circulation. Systole and diastole are the standardized terms used in cardiology to define the cardiac cycle clearly.