Normal Haemopoiesis

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Tabuk University
Faculty of Applied Medical Sciences
Department Of Medical Lab. Technology
2nd Year – Level 4 – AY 1433-1434
Normal Haemopoiesis
‫إنتاج خاليــا الدم‬
Mr. Waggas Elaas, M.Sc, MLT
References
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For theory :
Essential Haematology, John Wiley & Sons Ltd ,6th Edition,Victor Hoffbrand.
Harmening, Denise. (2009) . Clinical Hematology and Fundamentals of Hemostasis. 5th
Edition, F. A. Davis Company
For practical :
Practical Haematology, Churchill Livingstone, Eighth edition, John V. Dacie, S. M. Lewis,
Fischbach and Dunning. (2009). A Manual on Laboratory Diagnostic Tests. 8th Edition.
Wolters Kluwer Health Lippincott Williams and Wilkins, PA
ATLAS:
Carr and Rodak. (2008). Clinical Hematology. 3rd Edition, Saunders/Elsevier
Internet site(s):
http://www.essentialhaematology6.com/default.asp = MCQs
http://www.hematologyatlas.com/
http://pathy.med.nagoya-u.ac.jp/atlas/doc/atlas.html
http://themedicalbiochemistrypage.org/
http://www.bloodline.net/
3
Marks
Final Theoretical exam : 40
 Final Practical exam : 20 (including written questions)
 1st Periodic exam : 10 theory, 5 Practical
 2nd Periodic exam : 10 theory, 5 Practical
 Homework and class activities : 5 Theory, 5 Practical
 Total : 100
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4
Objectives
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To introduce Hematology to the students as a new science.
To identify blood components and the function of each.
To know the sites of Hemopoiesis (blood production).
To know the different stages of cell production of each cell
linage.
To be able to differentiate between blood cells especially
white cells.
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What is hematology?

Hematology is the study of blood which is composed of
plasma (55%), and the formed elements which are:
– The erythrocytes (RBCs) (44%)
 Contain hemoglobin
 Function in the transport of O2 and CO2
– The Leukocytes (WBCs) and platelets (thrombocytes) (1%)
 Leukocytes are involved in the body’s defense against
the invasion of foreign antigens.
 Platelets are involved in hemeostasis which forms a
barrier to limit blood loss at an injured site.
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Functions of blood :
1.Transports O2 and Co2 between tissues.
2. Transports nutrients (Glucose, vitamins ..etc).
3. Take waste products such as lactic acid away from
the muscles ; and urea from the liver to the kidneys.
4. Maintain body temperature.
5. Defense – White blood cells.
6. Coagulation.
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Hematopoiesis = Hemopoiesis
Hematopoiesis is a term describing the formation
and development of blood cells.
 Hematopoiesis in the bone marrow is called
Medullary hematopoiesis.
 Hematopoiesis in areas other than the bone marrow
is called Extramedullary hematopoiesis
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Sites of Haemopoiesis
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Fetus :
0 – 2 months
Yolk sac
2 – 7 months
Liver
5 – 9 months
Bone marrow
Liver and spleen continue to produce cells until 2 weeks
after birth.
In infancy, all the B.M is hemopoietic with progression
to fatty tissues.
– Gradual replacement of active (red) marrow by inactive (fatty) tissue (50% of
hemopoietic B.M in adults is fatty tissues)
– Expansion can occur during increased need for cell production
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In adult life, hemopoietic B.M is restricted to
central skeleton – proximal ends of femurs
(‫ )عظم الفخذ‬and humeri.(‫)عظم العضد‬
 Hemopoiesis can extend to long bones.
 Liver & spleen can resume hemopoiesis =
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Extramedullary Hemopoiesis.
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First cell : Pluripotential Stem Cell (PCS)
Appear like small Lymphocyte.
 Rare in B.M : 1 in every 20 million nucleated
cell.
 Self – renewal capacity
B.M cellularity
remain constant.
Hemopoietic progenitors : When stem cells
differentiate
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1st progenitor cell : CFU-GEMM
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Colony Forming Unit – Granulocyte,
Erythrocyte, Monocyte, Megakaryocyte
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stem cell (self – renewal)
Stem cell
divide
Committed stem cell
(progenitor)
differentiation & division
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Stem cells are linked with Stromal cell
(adipocyte, fibroblast, endothelial cells,
macrophages).
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Stromal cells secrete substances needed by
stem cell to survive . ( collagen, fibronoectin,
growth factors).
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Growth factors are hormones that regulate
proliferation & differentiation of cells.
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Erythropoiesis and erythrocytes
Lifespan of Red cells – 120 days
 Non nucleated
 Biconcave disc
 Production regulated by Erythropoietin
 Needs Fe, B12, folate & other elements
for development.
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CFUe the first recognizable cell in this lineage. Large
cell with dark blue cytoplasm, central nucleus and
nuclei and slightly clumped chromatin. The
cytoplasm stains paler blue as it loses its RNA and
protein synthesis apparatus and nuclear chromatin
becomes more condense. The nucleus is finally
extruded from the late normoblast with in the
marrow and reticulocyte are formed which still
contains RNA and still can synthesize hemoglobin.
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WBCs = Leucocytes
Phagocytes
(granulocytes +monocytes)
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Immunocytes
(lymphocytes)
Neutrophils (polymorphs)
Eosinophils
Basophils
Monocytes
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Leucopoiesis
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Myeloblast
Promyelocyte
myelocyte
Metamyelocyte
Band/stab/juvenile
Neutrophil
Neutrophil
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Monocyte:
Monoblast
(myelomonblast)
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promonocyte
Monocyte
Macrophage
(in tissues)
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Lymphopoiesis
Primary lymphoid organs (lymphocytes develop)
 Bone marrow
 Thymus
Secondary lymphoid organs (specific immune responses are generated)
 Lymph nodes
 Spleen
 Lymphoid tissues
Lymphocytes
according to size : small & large lymphocytes
according to immunity : T & B lymphocytes
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B cells mature in the bone marrow and circulate in the peripheral blood until they
undergo recognition of antigen. The B-cell receptor is membrane-bound
immunoglobulin and after activation this is secreted as free soluble
immunoglobulin. At this point they mature into memory B cells or plasma cells
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T cells develop from cells that have migrated to the thymus where they
differentiate into mature T cells during passage from the cortex to the medulla.
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Thrombopoiesis
Platelets play a major role in primary hemostasis,
 Life span 7-10 days.
 Small discoid non nucleated.
 Produced in B.M by fragmentation of cytoplasm of
megakaryocytes.
 Megakaryocytes undergoes endomitotic division = DNA
replication without nuclear or cytoplasmic division.
 One megakaryocyte gives 1000 – 5000 plts
 Thrombopoietin hormone (produced by liver & kidney) is the
main regulator.
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Stem cell
megakaryoblast
promegakaryocyte
megakaryocyte
platelets
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Homework-1
1. List the organs or systems involved in adult hematopoiesis.
2. Describe a "pluripotent cell".
3. Define the following terms:
a. erythropoiesis
b. granulopoiesis
c. lymphopoiesis
d. megakaryopoiesis
4. Differentiate between a monocyte and a macrophage.
5. The hematopoietic stem cell is capable of :
a-Replication
b-Differentiation
c-Replication and differentiation
6. The process of hematpoiesis under the control of:
a- Growth hormone
b- Hematopoietic growth factorsc
c- Thyroid hormone
29
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