Red Blood Cell Production in the Human Bone
The Bone marrow contains two types of stem cells:
- Hematopoietic cells which can be used to make all the blood cell types in the body.
- Stromal cells which can produce fat, cartilage and bone.
Red blood cells, platelets and most white blood cells arise in the red bone marrow; some white blood cells develop in yellow marrow. Yellow marrow is yellow because it has a much higher number of fat cells.
Erythropoiesis - Red Blood Cell Production
A decrease in oxygen in the blood is detected by the kidneys which then secrete the hormone erythropoietin . This hormone stimulates Erythropoiesis, the process by which red blood cells (erythrocytes) are produced in the red bone marrow.
The body regulates the process of erythropoiesis so that a red blood cells are produced at a rate that is equal to the destruction of red blood cells. This enables the body to sustain adequate tissue oxygen levels.
A good example of how this works is when an athelete has to aclimatise if they travel to a higher altitude - the body is making more red blood cells to increase the oxygen levels in the blood.
Red marrow is not found in all the bones of the human body. It is found mainly in the flat bones, for example the hip bone, vertebrae and shoulder blades. Two types of osseous tissue form bones, compact bone and cancellous (spongy) bone. Red bone marrow is also found in the cancellous material found at the ends of the long bones - the femur and humerus. .
Bone Marrow Transplants
Bone marrow transplants are more commonly reserved for people with diseases of the blood, bone marrow or certain types of cancer. The procedure can have many complications so is only used on people with life threatening diseases. The process involves harvesting the healthy stem cells to replenish the bone marrow of the patient. These new stem cells then take over the production of the blood cells.