WellStar Health System announced Tuesday that it had agreed to buy Tenet Healthcare's five metro Atlanta hospitals for $575 million. The deal, if approved by regulators, would make Marietta-based WellStar easily the largest health system in the state of Georgia. WellStar would acquire North Fulton Hospital in Roswell, Spalding Regional Hospital in Griffin, Sylvan Grove Hospital in Jackson, Atlanta Medical Center and its South Campus, as well as Tenet's physician practices in Atlanta. In all, the Tenet facilities include 1,192 licensed hospital beds supported by about 4,300 team members and a medical staff of 1,390 physicians and advanced practice professionals, WellStar said.