The word erythropoiesis is derived from the Greek words erythro meaning red and poiesis meaning producing. The process by which red blood cells are produced is called erythropoiesis. Red blood cells are produced from bone marrow, liver, spleen and thymus. Again, it gets destroyed in the liver and spleen. There, the red blood cells change and produce bile acids called bilirubin and biliverdin. 10 million red blood cells are produced every second, while 10 million red blood cells are destroyed every second.