<prompt> Duration of atrial systole is:0.53 sec0.28 sec0.08 sec0.11 sec  <response>: Ans: d 0.11 sec Ref: Ganong, 22nd ed, p. 568; Mahapathra, p. 219Duration of various cardiac events Cardiac cycle-0.8 sec Ventricular systole-0.27 sec Ventricular diastole-0.53 sec Action potential-0.25 sec Absolute refractory period-0.20 sec Relative Refractory period-0.05 sec Isovolumeetric contraction-0.05 sec Protodiastole-0.04 secEnd diastolic volume- 130mlEnd systolic volume- 50mlEjection fraction 65- 70-90mlS1- 0.15secS2- 0.12secS3- 0.1 sec 