This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
The duration of atrial systole is: 
Select and explain. 
A. 0.80 second, B. 0.57 second, C. 0.11 second, D. 0.44 second
C: 0.11 second
Answer: C: 0.11 second 
Explanation: When the heart beats at a normal rate of 72/minute, duration of each cardiac cycle is about 0.8 second. 
ATRIAL EVENTS 
Atrial events are divided into two divisions: 

Atrial systole = 0.11 (0.1) sec.
Atrial diastole = 0.69 (0.7) sec. 

VENTRICULAR EVENTS 
Ventricular events are divided into two divisions: 

Ventricular systole = 0.27 (0.3) sec 
Ventricular diastole = 0.53 (0.5) sec. 

In clinical practice, the term 'systole' refers to ventricular systole and 'diastole' refers to ventricular diastole. Ventricular systole is divided into two subdivisions and ventricular diastole is divided into five subdivisions.