Biology - Body Fluids and Circulation Question with Solution | TestHub

The standard duration of a cardiac cycle is $0.8$ seconds.

It comprises three main phases: Atrial systole ($0.1$ s), Ventricular systole ($0.3$ s), and Joint diastole ($0.4$ s).

In the given diagram, the event A spans from $0.4$ s to $0.8$ s, which is a duration of $0.4$ seconds. This corresponds to Joint diastole.

The event B spans from $0.8$ s to $0.9$ s, which is a duration of $0.1$ seconds. This corresponds to Atrial systole, marking the beginning of the next cardiac cycle.

Therefore, A stands for Joint diastole and B stands for Atrial systole.

Answer: Joint diastole, Atrial systole