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Lecture-1-fourth year Assist. Prof Dr. Hussein ttali-nt-snammari
Hemopoiesis (Blood cells formaiion)
Blood : Suspension of differentiated mature non-dividing cells, (RBC,WBC and
platelets), synthesis in the bone marrow and released to the peripheral blood.
1 . lntroduction and definition
2 Origin and Sites of hemoPoiesis
3. Structure of the bone marrow
4. Control of hemopoiesis
5. Assisment of haemoPoiesis
I ntroduction and defi nition
The various kind of blood cells have a finite life span in circulation.II
Red btood cells about 120 days Production rate 2 x 10 cells/day. Neutrophils
10
lifespan 6hours production rate 3 x 10 cell/day, platelets forT-10 days production
ll
rate1x10 cell/day.
All these cells are required continuous replacement by new cells by process called
hemopoiesis
Hemo: blood cells
Poiesis: "The development or production of "
The word Hemopoiesis refers fo the production & development of qll the blood cells
including:
cr. Erythrocytes: ErythroPoiesis
b. Leucocytesr LeucoPoiesis
c. Thrombocytes: ThromboPoiesis.
Normal developments (sites) of hemopoiesis
Haemopoesis development sites divided into two periods:
1. Fetat period ( embryonic period) (intrauterine hemopoiesis: IUH) :
A. yolk sac: First Stem cells originate in the yolk sac region. At first
week-2 months from ( mesenchymal stem cells in the yolk sac).
B. Liver .. Al 2-7 IUH months where Stem cells migrate to liver and spleen, the
main sites.
C. Bone marrow : At 3 month - to the end of pregnancy. Bone marrow of whole
bony skeleton is the main site (medullary) of hemopoiesis.
2. Extrauterine tife. (Bone marrow the only site of hemopoiesis)
1 Infancy and earlY childhood.
All bony skeleton ( central and peripheral bones) the site of bone marrow ano
hemopoiesis.
2. Childhood and adult: Flat central bones and proximal ends of long
bones.
3. Elderly Red marrow confined to the flat, short bones of central skeleton
(vertebrae, ribs, sternum, skull, pelvic bones)

Note: Normal bone marrow can expand 6-8 time its normal capacity to

compensate blood cells loss
Extra medullary temePoirsis:
Ftematopoiesis in &e bone marrqvr' is q.a*ed medultary' trematopoiesls
Henn*topoi .s[s fu, at'*us qtfte" then the b'o,nq rnarrqw'[s ca]led e-xtramedu]Iary
hematopeiesis
priiu*iOullary hematopoiesis W. occur when the normal bone marrow can not
replace loss of blood. MaY occur ln
l.fetal hematopoietic tissue (liver and spleen),This lead to hepatomegaly
and/or sPlenomegalY'
2. Corticalbone:1his lead to bone softing and deformities
Anatomy (structure) of bone marrow
fhe bone marrow consist two Parts ,
supportive tissue
consist of four main cells tYPes:
A. Stem cells.
g. Erytnroid series: precursors of red blood cells
C. nnyLtoiO series : Precursors of white blood cells
D. MegakaryocYtes
a. macrophages (storage of
to regulate hemoPoiesis' and
b. fatty cells: EnergY storage.
c. Fibroblast
d, dentretic cells
e. Microcirculation
(white marrowt.
ffin d"ttru.ti"n of aged red cells' release of cytokines
defense mechanism),
Types of hemoPorests :
1. Stem cells.
a. Self Renswal bjy, Sy,nunetrical rnitotic division to restore stem cell quantity'
(Abili'ty to give rise to new stem celts)
b. As.yr.lnretrisnl division: Abiiity to dif,'fbrent'iate into any blood cells lines
(Pturipqtent COmr,rritm"nts Cells linage of erythrod , rnyelod and r'n'egakaryocytes)
2.Erytropoiesisseries(Stemcetts--CFUE-Proeythroblase-earlyErythoblast'
intermediate and late erythroblast, reticulocytes mature red cells ' Each cell has four
mitotic division to give 16 mature red cell'
3. .mylelopoiesii series ( stem cell -cFUM-Blast-promyelocytes-
myelocytes,metamye|ocytes,bandcel|sandmaturegranulocytes.
4. Megakaryopoiesis: to give platelets
Control (regutation ) of hemopoiesis
Hemopoiesis is a controlled process to maintain peripheral blood cells count in
normal physiological limits according to the human sex and age ' The main factors
for regulation of hemoPoiesis are:
A. Normal bone marrow environment( stromal tissue and microcirculation)
red marrow (parenchyma tissue) and stoma

B. Normal supply of nutrients(DNA and Hemoglobin substrates).

1. Minerals( iron, coPPer, cobalt),
2. Vitamins (B12,folic acid)
3. Proteins (Amino acids) .
C. Hormones: erythiopoietin, thrombopoietin, thyroid hormones, androgen'
D. Hemopoietic growth factors: Like siem cell growth factor' colony-stimulating
factors; include GM-CsF(granulocytes monocytes stimulating factor)' G-
CSF, lnterlikins.
E. Celluar and extracelluar adhesive molecules'
F. Normal pnystlogical needs: tissue hypoxia, infections, inflammation,
bleeding, growth, and Pregnancy.
Erythropoitein: Cytok ine - 95%is produced in the kidney' Necessary for erythroid
proliferation and differentiation. Absence results in apoptosis (programmed cell
beath) of erythroid cornmitted cells. Stimulated by tissue hypoxia secondar to
anaemia
Anemia of renal failure due to lack of EPO
Age Distribution the bone marraw
7. lnfant and early chitdhood (75% redmarrow: 25%o yellow marrow)
2. Adulthood: (50 red :50 fattY)
3. Erderly: (25% yellow marrow:75% red marrow)
Red Marrow: The active parenchymal marrow of hemopoiesis'
Yellow marrow (Fatty marrow): suppottive marrow and increase with age due to
degeneration process of red marrow'
Classification of anaemia :
A. Functional classification:
Hypoproliferative destruction (infective hematopoiesi s)'
B. Clinical classification: According to the causes of anemia (blood loss,
IDA, hemolysis).
c. Quantitative classification: Severity of anaemia : Mild,. Moderate and
sevelr based on amount of Hematocrit, Hemoglobin RBC count
D. Blood cell indices (MCY MCH, MCHC)
MCV (mean corpuscular volume),The average volume of RBC (t{ct)
MCV: Hct (PCV)/ RBC count =Normal range (80-96) fl (90+-- 10)
MCH (mean corpuscular hemoglobin) The average content of t{b in average RBC
MCH: HbRBC count (NR= 27-32 Pg)
MCHC (mean corpuscular hemoglobin concentration)
Express the average concentration of hemoglobin per unit volume of RBC'
MCHC = Hb/Htc (NV= 32-36%)


رفعت المحاضرة من قبل: Ahmed monther Aljial
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