WordNet (r) 3.0 (2006):

bloodstream
    n 1: the blood flowing through the circulatory system [syn:
         bloodstream, blood stream]

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "bloodstream":
   Rh factor, Rh-negative, Rh-positive, Rh-type, Rhesus factor,
   antibody, antigen, arterial blood, blood, blood bank, blood cell,
   blood count, blood donor, blood donor center, blood group,
   blood grouping, blood picture, blood platelet, blood pressure,
   blood serum, blood substitute, bloodmobile, circulation,
   clinical dextran, dextran, erythrocyte, globulin, gore, grume,
   hematics, hematologist, hematology, hematoscope, hematoscopy,
   hemocyte, hemoglobin, hemometer, humor, ichor, isoantibody,
   leukocyte, lifeblood, neutrophil, opsonin, phagocyte, plasma,
   plasma substitute, red corpuscle, serum, type O, venous blood,
   white corpuscle