A-V Valves Open; Semilunar Valves Closed. This is the first phase of the cardiac cycle. It is initiated by the P wave of the electrocardiogram (ECG), which represents electrical depolarization of the atria. Atrial depolarization initiates contraction of the atrial musculature.
Community Q&A. You can calculate age on Excel for a many applications by combining an undocumented function and the date format for cells. Microsoft Excel internally stores dates as serial numbers, which is the number of days a date is from Jan. 1, 1900.
Dates are simply numbers. Excel's date range is Jan 1, 1900, day 1 through. Dec 31, 9999, day 2,958,465. If the age is in A1 then you could use. =(TODAY()-A1*365.25) to get an approximation and format the answer as a. date. But be aware that you could be off by almost a whole year.