Hematopoiesis is the formation of blood cells that occurs primarily in the red bone marrow found in flat bones such as the pelvis, ribs, sternum, and ends of long bones. The production of red blood cells is controlled by the hormone erythropoietin (EPO) which is produced by the kidneys and stimulates the bone marrow to make more red blood cells when oxygen levels fall. A common stem cell called the hematocytoblast located in the red bone marrow gives rise to all formed elements of blood including lymphocytes from lymphoid stem cells and other blood components from myeloid stem cells.

1. Hematopoiesis (The
formation of Blood Cells)

2. 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.

3. 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

4. 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

5. 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)

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

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

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

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

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

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

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

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

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

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

18. Amino
acids
Reused for
protein synthesis
Globin
Circulation for about
120 days
Bilirubin
Red blood cell
death and
phagocytosis
Transferrin
Fe3+
Fe3+ Transferrin
Liver
+
Globin
+
Vitamin B12
+
Erythopoietin
Key:
in blood
in bile
Erythropoiesis in
red bone marrow
Macrophage in
spleen, liver, or
red bone marrow
Ferritin
Heme
Biliverdin Bilirubin
Fe3+
1
0
9
8
7
6
5
4
3
2
1

19. Amino
acids
Reused for
protein synthesis
Globin
Stercobilin
Bilirubin
Urobilinogen
Feces
Small
intestine
Circulation for about
120 days
Bacteria
Bilirubin
Red blood cell
death and
phagocytosis
Transferrin
Fe3+
Fe3+ Transferrin
Liver
+
Globin
+
Vitamin B12
+
Erythopoietin
Key:
in blood
in bile
Erythropoiesis in
red bone marrow
Macrophage in
spleen, liver, or
red bone marrow
Ferritin
Heme
Biliverdin Bilirubin
Fe3+
1
2
1
1
1
0
9
8
7
6
5
4
3
2
1

20. Amino
acids
Reused for
protein synthesis
Globin
Urine
Stercobilin
Bilirubin
Urobilinogen
Feces
Small
intestine
Circulation for about
120 days
Bacteria
Bilirubin
Red blood cell
death and
phagocytosis
Transferrin
Fe3+
Fe3+ Transferrin
Liver
+
Globin
+
Vitamin B12
+
Erythopoietin
Key:
in blood
in bile
Erythropoiesis in
red bone marrow
Kidney
Macrophage in
spleen, liver, or
red bone marrow
Ferritin
Urobilin
Heme
Biliverdin Bilirubin
Fe3+
1
3
1
2
1
1
1
0
9
8
7
6
5
4
3
2
1

21. Amino
acids
Reused for
protein synthesis
Globin
Urine
Stercobilin
Bilirubin
Urobilinogen
Feces
Large
intestine
Small
intestine
Circulation for about
120 days
Bacteria
Bilirubin
Red blood cell
death and
phagocytosis
Transferrin
Fe3+
Fe3+ Transferrin
Liver
+
Globin
+
Vitamin B12
+
Erythopoietin
Key:
in blood
in bile
Erythropoiesis in
red bone marrow
Kidney
Macrophage in
spleen, liver, or
red bone marrow
Ferritin
Urobilin
Heme
Biliverdin Bilirubin
Fe3+
1
4
1
3
1
2
1
1
1
0
9
8
7
6
5
4
3
2
1