Question

The accompanying diagram shows the three stages in the cardiac cycle.


Which of the following is the correct sequence?

• A. B, A, C
• B. B, C, A
• C. C, A, B
• D. C, B, A

Answer 1

The correct option is A B, A, C

In the given image,
Diagram A = Atrial systole
Diagram B = Joint diastole
Diagram C = Ventricular systole

The cardiac cycle starts with a joint diastole (B) during which both the auricles and the ventricles remain relaxed. The auricles get filled with blood during this phase.
This is followed by auricular or atrial systole (A) during which the auricles contract and pump blood into the ventricles. At this time the ventricles undergo diastole and are relaxed.
Next is the ventricular systole (C) and simultaneous auricular diastole. The right and left ventricles contract to pump blood into the pulmonary artery and aorta, respectively. The auricles remain relaxed. The cycle ends here and at the end of the cycle the ventricles relax along with the auricles, thus marking the beginning of the joint diastole of the next cycle.
Hence, the order is B, A, C.