How is Activity Monitor Pulling processes specific memory information?

How is SQL Server Management Studio's Activity Monitor pulling the following memory by processes information? The screen I am talking about is... Log into the database, right click on the server in the tree on the left and select activity monitor. Expand out processes. The Memory Use column - where is it coming? Is there an internal database table that it is pulling from? I ask because I am trying to figure what all goes into this metric so I can determine if one of the processes is growing without bound or growing as expected due to design.