Where are the rbc's made?

Red blood cells (RBCs) are primarily produced in the bone marrow, a spongy tissue found in the center of certain bones. In adults, this process mainly occurs in the vertebrae, ribs, sternum, and pelvis. The production of RBCs, known as erythropoiesis, is stimulated by the hormone erythropoietin, which is produced by the kidneys in response to low oxygen levels in the blood.