Hematopoiesis (The formation of Blood Cells)‏

Where Does it Happen? Occurs in the Red Bone Marrow Red Bone Marrow is Found in the flat bones of the: 1. Pelvis 2. Ribs 3. Sternum 4. Ends of the Femur and Humerus in adults.

How is it controlled? Each blood cell type is produced according to need Levels of the hormone Erythropoietin (EPO) control the rate of RBC production EPO is produced by the kidneys

How does EPO work? We always have a little EPO flowing through us to ensure constant RBC production If Oxygen levels fall, levels of EPO rise and more RBC’s are produced The increase in EPO stimulates the red bone marrow to produce the new cells High levels of oxygen in the blood will lower the amount of EPO and slow down RBC production

The Hematocytoblast Common stem cell that gives rise to all the formed elements of blood Located in the red bone marrow Forms two types of cells 1. Lymphoid Stem cell- produces all lymphocytes 2. Myeloid Stem Cell- produces all other formed elements (RBC’s plasma)

Formation and Destruction of Red Blood Cells Process Diagrams Step-by-Step Copyright © 2007 by John Wiley & Sons, Inc.

1 Key: Red blood cell death and phagocytosis Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

2 1 Key: Globin Heme Red blood cell death and phagocytosis Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

3 2 1 Key: Amino Reused for protein synthesis acids Globin Heme Red blood cell death and phagocytosis Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

3 4 2 1 Key: Amino Reused for protein synthesis acids Globin Fe3+ Heme Transferrin 1 Red blood cell death and phagocytosis Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

3 4 5 2 1 Key: Amino Reused for protein synthesis acids Globin Fe3+ Heme Ferritin Transferrin Liver 1 Red blood cell death and phagocytosis Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

3 6 4 5 2 1 Key: Amino Reused for protein synthesis acids Fe3+ Transferrin Globin 6 4 5 Fe3+ 2 Heme Ferritin Transferrin Liver 1 Red blood cell death and phagocytosis Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

7 3 6 4 5 2 1 Key: Amino acids Reused for protein synthesis Fe3+ Transferrin Globin 6 4 5 Fe3+ 2 Heme Ferritin Fe3+ Transferrin + Globin + Liver Vitamin B12 1 Red blood cell death and phagocytosis + Erythopoietin Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

7 3 6 4 5 2 1 8 Key: Circulation for about 120 days Amino acids Reused for protein synthesis Fe3+ Transferrin Globin 6 4 5 Fe3+ 2 Heme Ferritin Fe3+ Transferrin + Globin + Liver Vitamin B12 1 Red blood cell death and phagocytosis + Erythopoietin 8 Erythropoiesis in red bone marrow Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

7 3 6 4 5 2 9 1 8 Key: Circulation for about 120 days Amino acids Reused for protein synthesis Fe3+ Transferrin Globin 6 4 5 Fe3+ 2 Heme Ferritin Fe3+ Transferrin + Globin 9 + Biliverdin Bilirubin Liver Vitamin B12 1 Red blood cell death and phagocytosis + Erythopoietin 8 Erythropoiesis in red bone marrow Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

7 3 6 4 5 2 9 1 10 8 Key: Circulation for about 120 days Amino acids Reused for protein synthesis Fe3+ Transferrin Globin 6 4 5 Fe3+ 2 Heme Ferritin Fe3+ Transferrin + Bilirubin Globin 9 + Biliverdin Bilirubin Liver Vitamin B12 1 Red blood cell death and phagocytosis + 10 Erythopoietin 8 Erythropoiesis in red bone marrow Macrophage in spleen, liver, or red bone marrow Key: in blood in bile

7 3 6 4 5 2 9 11 1 10 8 12 Key: Circulation for about 120 days Amino acids Reused for protein synthesis Fe3+ Transferrin Globin 6 4 5 Fe3+ 2 Heme Ferritin Fe3+ Transferrin + Bilirubin Globin 9 + Biliverdin Bilirubin Liver Vitamin B12 1 Red blood cell death and phagocytosis 11 + 10 Erythopoietin Small intestine 8 Erythropoiesis in red bone marrow Bilirubin 12 Macrophage in spleen, liver, or red bone marrow Urobilinogen Bacteria Key: in blood Stercobilin in bile Feces

7 3 6 4 5 2 9 11 1 10 8 13 12 Key: Circulation for about 120 days Amino acids Reused for protein synthesis Fe3+ Transferrin Globin 6 4 5 Fe3+ 2 Heme Ferritin Fe3+ Transferrin + Bilirubin Globin 9 + Biliverdin Bilirubin Liver Vitamin B12 1 Red blood cell death and phagocytosis 11 + 10 Erythopoietin Small intestine Kidney 8 Erythropoiesis in red bone marrow Bilirubin 13 12 Urobilin Macrophage in spleen, liver, or red bone marrow Urobilinogen Bacteria Key: in blood Stercobilin in bile Urine Feces

7 3 6 4 5 2 9 11 1 10 8 13 12 Key: 14 Circulation for about 120 days Amino acids Reused for protein synthesis Fe3+ Transferrin Globin 6 4 5 Fe3+ 2 Heme Ferritin Fe3+ Transferrin + Bilirubin Globin 9 + Biliverdin Bilirubin Liver Vitamin B12 1 Red blood cell death and phagocytosis 11 + 10 Erythopoietin Small intestine Kidney 8 Erythropoiesis in red bone marrow Bilirubin 13 12 Urobilin Macrophage in spleen, liver, or red bone marrow Urobilinogen Bacteria Key: in blood Stercobilin Large intestine 14 in bile Urine Feces