How many red blood cells does the bone marrow produce every second?
Red blood cells are formed in the red bone marrow of bones. Stem cells in the red bone marrow called hemocytoblasts give rise to all of the formed elements in blood. The formation of a red blood cell from hemocytoblast takes about 2 days. The body makes about two million red blood cells every second. Blood is made up of both cellular and liquid components. Blood consists of 45% red blood cells, less than 1% white blood cells and platelets, and 55% plasma.