lectures series in basic hematology

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2.  Also known as:
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3.  RES is an essential component of
the immune system.
 The main organs include the liver,
spleen, lymph nodes, bone marrow,
thymus and intestinal tract
associated lymphoid tissue.
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4. Cellular components of RES
1. Monocytes.
2. Macrophage Located in all
tissues such as skin (Langerhans
cells ), liver (kupffer), spleen,
bone marrow, lymph nodes, lung.
3. Endothelial cells: bone marrow,
spleen, lymph node.
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5. Macrophages
 Often remain fixed to their
organs. They filter and destroy
objects which are foreign to the
body, such as bacteria, viruses.
 Some macrophages are mobile, and
they can group together to
become one big phagocytic cell in
order to ingest larger foreign
particles.
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6. Formation of
Macrophages
1. Begin by Stem cell in Bone Marrow:
- Monoblast promonocyte mature monocytes
(released into blood).
2. Stay for 10-20 hours in circulation.
3. Then leave blood to tissues transforming
into larger cells macrophage.
4. Macrophage life span is longer up to few
months in tissues.
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7. FIXED TISSUE MACROPHAGES
 Known by different names in different sites.
The nameThe organ
Kupffer cellsLiver
Alveolar macrophagesLung
Langerhans cellsSkin
HistiocytesConnective tissue
MicrogliaCNS
OsteoclastsBone
Reticular or Dendritic
cells
Spleen/Bone
marrow/Lymph nodes
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8. Characterized by an increase in:
 Cell size.
 Number and complexity of
intracellular organelles Golgi,
mitochondria, lysosomes.
 Intracellular digestive enzymes.
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9. FUNCTIONS OF THE RES
1. Phagocytosis: Bacterial, dead
cells, foreign particles (direct).
2. Immune function: processing
antigen and antibodies production
(indirect).
3. Formation of bile pigments.
4. Breakdown of aging RBC.
5. Storage and circulation of iron.
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10. Phagocytosis
 Phagocytosis is part of the
natural or innate immune process.
 Macrophages are a powerful
phagocytic cells:
 Ingest up to 100 bacteria.
 Ingest larger particles such as old
RBC.
 Get rid of waste products.
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11. Direct anti-inflammatory
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12. Mechanism of phagocytosis
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13. Indirect Immune role Of RES
 Indirect immune function of RES:
◦ Ingest foreign body, process it and
present it to lymphocytes.
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14. Antigen processing
 Antigen processing: degradation of
proteins into peptides that can be
presented on MHC I or MHC II
◦ MHC I presents peptides derived from
cytoplasmic antigens
◦ MHC II presents peptides derived from
extracellular or intravesicular antigens
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15. Antigens are derived from cytosolic
or vesicular compartments
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16.  The lymphatic system is composed of:
1. Primary lymphoid organs: include the
bone marrow and the thymus.They create
special immune system cells called
lymphocytes.
2. Secondary lymphoid organs: These organs
include the lymph nodes, the spleen, the
tonsils and certain tissue in various mucous
membrane layers in the body (e.g. in the
bowel).
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17.  Lymph nodes filter lymph before it is
returned to the blood
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18.  Leukocyte defense cells within
lymph nodes:
◦ Macrophages – engulf and destroy
foreign substances
◦ Lymphocytes – provide immune response
to antigens
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19.  Thymus:
◦ Produces hormones (like thymosin) to
program (“educate”) certain lymphocytes
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20.  Tonsils:
◦ Small masses of lymphoid tissue around
the pharynx
◦ Trap and remove bacteria and other
foreign materials
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21.  Peyer’s Patches:
◦ Found in the wall of the small intestine
◦ Capture and destroy bacteria in the
intestine
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22.  It is a soft purple gray in color located in the
left upper quadrant of the abdomen.
 It is a highly vascular lymphoid organ.
 It is the part of RES and its absence leads to
a predisposition toward certain infections.
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23. : provides
the immune function of
the spleen.
 Red pulp: surrounds
white pulp, composed
of Venous sinuses filled
with whole blood and
Splenic cords of
reticular connective
tissue rich in
macrophages.
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24. 1. Haematopoiesis: fetal life.
2. Spleen is a main site for
destruction of RBCs specially old
and abnormal e.g. spherocytosis.
3. Blood is filtered through the
spleen.
4. Reservoir of thrombocytes and
immature erythrocytes.
5. Recycles of iron.
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25. 1. Because the organ is directly
connected to blood circulation, it
responds faster than other lymph
nodes to blood-borne antigens.
2. Destruction and processing of
antigens.
3. Reservoir of lymphocytes in white
pulp.
4. Site for Phagocytosis of bacteria
and worn-out blood cells.
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26.  Impaired splenic function or
splenectomy lead to:
Reduce the ability to make antibody,
particularly to capsulated organisms.
Reduces clearance of intracellular
organisms (e.g. parasitized red
cells).
Impairs defense against organisms
and toxins in the portal circulation.
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27. It is the central factory for production of
all adult hematopoietic cells.
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28.  Bone marrow is a highly cellular,
viscous , and highly vascular tissue
present within the hollow cavities of
hard bone and is specially designed
to support the proliferation,
differentiation, and maturation of
hematopoietic cells .
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29.  Depending on proportion of adipocytes &
hemopoietic cells.
1. RED: (rich in haemopoietic cells).
2. YELLOW: (composed of fat cells)
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30. 1. Vascular compartment
2. Hematopoietic compartment
a) Hematopoietic cells
b) Stromal cells
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31.  Cells of the BM:
Erythroid series
Myeloid series
Megakaryocytic series
Monocytic series
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32. Cellularity
(hematopoietic/fat cell)
SiteAge
100/0All bones, liver &
spleen
Newborns
70/30Most bonesChildren
50/50Axial bonesAdults
30/70Axial bonesOld age
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Marrow cellularity vary according
to age.

33. Myeloid : Erythroid ratio (M:E)
 The M:E ratio is the ratio of all
granulocytic plus monocytic cells
(Myeloid) to all erythroblasts
(Erythroid).
 Lymphocytes, monocytes and plasma
cells are not included in the M:E ratio.
 The normal ratio of 3:1 to 4:1 reflects
the relationship between production
and life span of the various cell types.
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34. Alteration in M:E ratio
 Normal M:E:
Does not reflect changes, as both series
are equally affected—e.g., in aplastic
anaemia, myelosclerosis, chloramphenicol
toxicity.
 Decreased M:E:
- Haemolytic and megaloblastic anaemias.
 Increased M:E:
- CML, leukaemoid reactions.
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