HEMATOLOGY INTRODUCTION
Organization of blood and blood forming organs
CLS245
WHAT IS HEMATOLOGY?
 Hematology
is the study of blood which is
composed of plasma (~55%), and the
formed elements which are:

The erythrocytes (RBCs) (~45%)
Contain hemoglobin
 Function in the transport of O2 and CO2


The Leukocytes (WBCs) and platlets
(thrombocytes) (~1%)
Leukocytes are involved in the body’s defense against
the invasion of foreign antigens.
 Platelets are involved in hemostasis which forms a
barrier to limit blood loss at an injured site.

COMPOSITION OF BLOOD
TYPES OF FORMED ELEMENTS IN THE
BLOOD
WHAT IS HEMATOLOGY?
 Hematology
is primarily a study of the
formed cellular elements.
 Alterations in the formed elements in the
blood are usually a result of disease
rather than being the primary cause of
disease.
WHAT IS HEMATOLOGY?

Hematopoiesis is a term describing the formation
and development of blood cells.
HEMATOPOIESIS
Mesoblastic stage



Nucleated RBCs - Yolk sac and Mesothelial layers of the placenta –
3rd week
Hepatic stage

Primitive erythroblast > migrate to liver and spleen (6wks) – includes
other myeloid and lymphoid cells.
Myeloid stage

•
From the third month onwards - the bone marrow gradually
becomes the principal source of the RBCs
•
Last month (9th month) – Bone marrow exclusively
HEMATOPOIESIS
•
At birth the bone cavities are the only site of
hematopoietic activity - Starts at the 7th months
•
Yolk sac > fetal liver/spleen > BM
ORIGIN OF HEMATOPOIESIS
Relative rates of red blood cell production in the
bone marrow of different bones at different ages.
HEMATOPOIESIS
Hematopoietic stem cell pool
Pluripotential - multipotential stem cells (MSCs)
 morphologically identical
 Continuous self-renewal

Unipotential - committed progenitor cells
 Restricted to single cell line
 No self-renewal
 Lymphoid or myeloid

MATURE RED CELL
(RBC)
Size: 6 to 8 μm
 Appearance: Diskshaped cell filled with
hemoglobin, having an
area of central pallor
of 1 to 3 μm

MATURE RBCS




Size: 6 to 8 μm, having an
area of central pallor of 1
to 3 μm,
Biconcave discs, no
nucleus, essentially no
organelles.
Filled with hemoglobin
(Hb), a protein that
functions in gas transport.
Contain the plasma
membrane protein spectrin
and other proteins that
give erythrocytes their
flexibility and allow them
to change shape as
necessary.
HEMOGLOBIN
HB is a highly specialized
intracellular erythrocyte protein,
responsible for transport O2 from the
lung to the tissues and CO2 from
tissues to the lung.
 It is a tetramer, consisting of two
pairs of similar polypeptide chains
called globins, To each of the four
chains is attached a prosthetic
group, heme, a complex of iron and
protoporphyrin.

RED BLOOD CELLS DISORDERS
Anemia
Is a reduction of circulating red blood cells,
hemoglobin, and packed cell volume to a level lower
than the normal range.
It can be classified according to the etiology, or to the
morphological appearance of the RBCs under light
microscope.
1- Morphological classification:
 Microcytic hypochromic anemias:
Ex. Iron deficiency anemia
 Macrocytic normochromic anemias:
Ex. Megablastic anemia
 Normocytic normochromic anemias:
Ex. Sickle cell anemia
2- Etiological classification:
 This classification is based on the cause of anemia.
 Increase destruction.
 Decrease production.
 Blood loss (hemorrhage).
TYPES OF WBCS NORMALLY SEEN ON SMEAR
WHITE BLOOD CELLS DISORDERS


Leukemia = lymphoid and myeloid malignant bone marrow
neoplasms
 when abnormal cells are seen in both the bone marrow and
the peripheral blood
Lymphoma = abnormal proliferation of lymphoid cells within the
lymphatic tissue or lymph nodes
Leukemia:



Acute leukemia = rapid onset with abnormal expansion of
immature cells
Chronic leukemia = slow progression with abnormal expansion
of mature cells
Divided by two cell types: myeloid and lymphoid
 Acute myeloid leukemia (AML), or chronic myeloid leukemia
(CML)
 Acute lymphoid leukemia (ALL), or chronic lymphoid
leukemia (CLL)
HEMOSTASIS
Hemostasis can be defined as: the stoppage of
bleeding from the blood vessels
 It is a complex process in which several factors
work together or in sequence to stop the flow of
blood from an injured blood vessel.
 The five major components of normal hemostasis
are blood vessels constriction, platelets,
coagulation factors, coagulation inhibitors and
fibrinolysis.

PLATELETS

Platelets are small fragments of cytoplasm
derived from megakaryocytes. On average they
are 1.5–3.5 μm in diameter but may be larger in
some diseases.
HEMOSTASIS DISORDERS
EX. Immune thrombocytopenic purpura (ITP) is
one of the most common autoimmune disorders.
ITP is caused by autoantibodies to platelets. The
antigenic target in most patients appears to be the
platelet GP IIb/IIIa complex. Platelets with
antibodies on their surface are trapped in the
spleen, where they are efficiently removed by
splenic macrophages.
HEMATOLOGY LAB TESTS
1- The complete blood count, or CBC
lists a number of many important values. Typically, it includes the following:
White
WBC
Red
blood cell count (WBC or leukocyte count)
differential count
blood cell count (RBC or erythrocyte count)
Hematocrit
(Hct)
Hemoglobin
(Hbg)
Mean
corpuscular volume (MCV)
Mean
corpuscular hemoglobin (MCH)
Mean
corpuscular hemoglobin concentration (MCHC)
Red
cell distribution width (RDW)
Platelet
Mean
count
Platelet Volume (MPV)
HEMATOLOGY LAB TESTS
2- Sickle cell test
3- peripheral blood film
4- Erythrocyte Sedimentation Rate
nonspecific test “ look for general infection only “
5- Hb Electrophoresis
6- Coagulation tests “ PT, APTT, TT, D-Dimer”
7- Bone marrow aspiration.