A turbine blade (10) including an airfoil (12) having multiple interior wall portions (70) each separating at least one chamber from another one of multiple chambers (46, 48, 50, 58, 60). In one embodiment a first wall portion (70-2) between first and second chambers (60, 52) includes first and second pluralities of flow paths (86P, 86S) extending through the first wall portion. The first wall portion includes a first region R1 having a first thickness, t, measurable as a distance between the chambers. One of the paths extends a first path distance, d, as measured from an associated path opening (78) in the first chamber (60), through the first region and to an exit opening (82) in the second chamber (52) which path distance is greater than the first thickness.