One complete contraction and relaxation of all four chambers of the heart is called what?

• A. Cardiac Cycle
• B. Blood Pressure
• C. Stroke Volume
• D. Heart Rate

Answer: (A)

The cardiac cycle describes the sequence of events that occur during one heartbeat, including the contraction and relaxation of all four chambers. It encompasses atrial systole helping fill the ventricles, followed by ventricular systole pumping blood into the arteries, and then diastole when the chambers relax and refill, with valve actions coordinating the flow. This single cycle captures the entire mechanical activity of the heart from one beat to the next. Blood pressure is the force of blood against vessel walls, not the overall sequence; stroke volume is the amount of blood moved per beat, and heart rate is how many beats occur per minute—both describe parts of the process or its rate, not the whole cycle itself.