How is Blood Produced?

Your blood is produced within the bone marrow and this bone marrow is referred to as red marrow. In the bone marrow there are stem cells called pluripotential hematopoietic stem cells where all blood cells come from. As the blood cells develop from these stem cells they pass through the red marrow and seep into the bloodstream. In the event the body needs more red blood cells, if the bodily oxygen levels become low, the kidneys produce erythropoietin, a hormone, which signals the stem cells to produce more red blood cells.