Described is an apparatus for oxygenating and controlling the temperature of blood in an extracorporeal circuit, the apparatus having an inlet and an outlet that is located radially outward from the inlet in order to define a flowpath through the apparatus, the apparatus comprising: a core in communication with the inlet such that blood from a patient can be supplied to the core, the core comprising a first element and a second element that interfit to define openings, wherein the elements and the openings together enhance flow of blood from the patient radially outward from the core; a heat exchanger that is arranged about the core and through which blood from the core can move radially outward; and an oxygenator that is arranged about the heat exchanger and through which blood from the heat exchanger can move radially outward before exiting the apparatus through the outlet.