The phase in the cardiac cycle where both the ventricles and atria are in a relaxed state.
Blood passively enters into both the atrium filling around 2/3rd of it.
It is for 0.3 secs before the atrium contraction.
Both AV and semilunar valves are closed during this phase.
Final Answer:
Joint diastole is a phase when both atria are in relaxed state for 0.3 seconds of cardiac cycle