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.
1 Excel's DATEDIF Function If you regularly work with dates and times in Excel, then it is worth learning how some of Excel's date-related functions operate. 2  There are over 20 functions in this group, â¦. 3  How to Quickly Sum a Column in Excel SUM is one of the commonly used functions in Excel. One of the most useful functions in Excel is the IF function. What it does is test a value in a specific cell to see if that value meets a certain condition. If the valu â¦ e does meet the condition, one result will happen, if false, a different action will occur.