A gas turbine engine includes a compressor, combustor, and high pressure turbine operatively joined together. The turbine includes a row of nozzle vanes followed by a row of rotor blades. The vanes and blades have corresponding forward and aft internal cooling channels. First, second, third, and fourth bleed circuits are joined in flow communication with different stages of the compressor for bleeding pressurized air therefrom at different pressures to provide coolant to the forward and aft channels of the turbine vanes and blades.