Hematology Lecture

INTRODUCTION TO HEMATOLOGY
Hematology - deals with the study of the clinical, morphologic and laboratory disorders of the blood and the blood forming organs.
Analysis of: concentration, structure and function of cells
- Precursors in the bone marrow
- Chemical constituents of plasma or serum
- Functions of platelets
- Proteins in hemostasis and coagulation
Circulation: heart - arteries - capillaries - veins - back to the heart
Blood is a: CT
Functions of blood:
1. Transports oxygen from lungs to tissues
2. Transports carbon dioxide from the tissue to the lungs for elimination
3. Transports food material
4. Picks up metabolic end products and deliver it to the organs for use or elimination (moves waste to the liver or kidney)
5. Aids in body temperature
6. Transports hormones
7. Maintains optimal pH of the acid (acid-base equilibrium) = 7.35 to 7.45
8. Regulates water balance
9. A mobile defense mechanism to protect the body from invasion and disease (leukocytes and immune bodies in the blood
stream)
10. Maintains a degree of irritability of the tissue cells so that functional activity can be carried on satisfactorily.
- Carries substances - tissue cells - answer stimulus = irritability
11. Transports glucose, proteins, and fats
12. Plasma contains coagulation enzymes that aids in protecting the vessel from trauma and maintain circulation
Average L in human: 5 liters

LIQUID PORTION
PLASMA (55%)
Function: transports and nourishes blood cells
Characteristics:
a. Fluid portion of blood
b. Straw colored
c. Remains when no coagulation is done
d. NO FIBRINOGEN
Constituents:
a. Water - 95%
b. Inorganic constituents (ELECTROLYTES) - sodium, calcium, potassium, magnesium, chloride, bicarbonate, phosphate, sulfate
c. Organic constituents: dissolved in plasma
- Plasma proteins:
I. Albumin - colloid osmotic (causes osmotic pressure in the capillary membrane)
- Prevents fluid of plasma to leak out of the capillaries into the interstitial spaces
II. Globulin
II.a. Alpha and beta globulins - transport substances by combining with them, acting as substrates that react with
other substances, transporting protein itself from one part of the body to another.
II.b. Beta and gamma globulins - protection against infection
II.c. Gamma globulins - provides immunity: how? Contains antibodies that prevent toxicity and resists infection
III. FIbrinogen - blood clotting
IV. Internal secretions (hormones) - antibodies and enzymes (amylase, protease[proteins], lipase[lipids])
V. Gases - O2, CO2, N

SOLID PORTION (41-45%)

- Cellular elements:
a. RBC
b. WBC
c. PLATELETS

Plasma - 55%
Buffy coat - 4% (wbc and platelets)
RBC - 41%

***Band - immature neutrophils / aka Stab cells

RED BLOOD CELLS

Characteristics: anucleate, biconcave, discoid cells
Contains: hemoglobin(red pigment)
Function: transports O2 and CO2
Color: pink to red
SIze: 6 to 8 μm
Why are they biconcave in shape? Because of the zone pallor that occupies ⅓ of the center portion
Detects: Anemia - insufficient amount of rbc = low HGB = low O2
 - loss of oxygen-carrying capacity and is often reflected in a reduced RBC count or decreased RBC hemoglobin concentration
Polycythemia - hyperviscosity // increased RBC count reflecting increased circulating RBC mass
Tests:
a. Hemoglobin (Cyanmethemoglobin method-Drabkin’s reagent)
- Drabkin reagent: potassium cyanide + potassium ferricyanide
- Converts hemoglobin to cyanmethemoglobin (hemoglobincyanide) and the color intensity of the solution is measured with
the use of spectrophotometer at 540 nm wavelength
- Replacement: sodium lauryl sulfate (ionic surfactant detergent) to reduce environmental cyanide
- Hyperchromic (high HGB content)
- Hypochromic (low HGB content)

b. Hematocrit count/packed cell volume (PCV)

- Total ratio of RBC to the total ratio of whole blood
- Determines packed cell of RBC LAYER

c. RBC count
- Whole blood is diluted
- Lyse RBC and cellular debri
- Use of hemocytometer and is counted under the microscope

d. RBD indices
- MCV (mean cell volume) = recorded in femtoliters (fL), reflects RBC diameter on a Wright-stained blood film.
- MCH (mean cell hemoglobin) = picograms (pg), mass of HGB and parallels MCHC
- MCHC (mean cell hemoglobin concentration) = expressed in g/dL, reflects RBC staining intensity and amount of central
pallor.

e. RDW (RBC distribution width)

- Variation in RBC volume
- Anisocytosis = unequal in size / varies in diameter / anemia
- Wright stain blood film

f. Reticulocyte count
- Immature RBC / “retics”
- Wright-stained blood film, 0.5% to 2% of RBCs exceed the 6- to 8-mm average diameter and stain slightly blue-gray.
- Polychromatophillic (newly released rbc from bone marrow) - stains - diagnostic colors - blood smears
- Methylene blue dyes, called nucleic acid stains or vital stains, are used to differentiate and count these young RBCs.
- Vital (or “supravital”) stains are dyes absorbed by live cells.9
- Has RNA that's why it is called RETICULOCYTES

WHITE BLOOD CELLS 4500 to 11,500/mL.

Function: protection against injury and infection
Source: bone marrow or lymphoid tissue
*** colorless in an unstained cell suspension***
Detects: Leukocytosis - increased WBC count // inflammation
Leukopenia - decreased WBC count
Differentiation: Wright-stain and light microscopy
Types of WBC:
Granulocytes: prominent cytoplasmic granules
a. Neutrophils - phagocytosis
- Segmented neutrophils: multilobed nuclei
- Increase in neutrophils: neutrophilia (usually indicates bacterial infection)
- Decrease in neutrophils: neutropenia (medications or viral infections)
- Band neutrophils: less mature
- Increase in band neutrophils: Left shift
- Cytoplasm: pink or lavender granules used for bactericidal secretions

b. Eosinophils - involved in immune system regulation

- Increase in EO: eosinophilia (allergy or parasitic infection)
- Cytoplasm: bright red-orange, regular cytoplasmic granules

c. Basophil - allergic and antigen response

- Cytoplasm: dark purple, irregular cytoplasmic granules that obscure the nucleus
- Granules contains histamines and other proteins
- Increase in basophils: basophilia (rare, hematologic disease)
***leukemia - uncontrolled proliferation of WBC

Agranulocytes:
a. Lymphocytes - provides host immunity / recognizes Ag and mount humoral (Ab) and cell-mediated responses
- Nearly round, slightly larger than RBC
- Cytoplasm: nongranular (thin rim)
- Nuclei: round featureless
- Increase in lymphocyte: lymphocytosis (viral infection)
 - Decrease in lymphocyte: lymphopenia/lymphocytopenia (drug therapy or immunodeficiency)

b. Monocytes - identify and phagocytose foreign material

- Assist lymphocytes in assembly and presentation of epitopes
- Immature macrophage (blood) -> becomes macrophage in tissue
- More abundant
- Wright-stained blood smear
- Cytoplasm: blue-gray with fine azure granules
- Nucleus: indented or folded
- Size: slightly larger in diameter with other WBC
- Increase in monocytes: monocytosis (chronic and acute leukemia and collagen-vascular diseases)
- Monocytopenia: seldom

PLATELETS
Functions: maintain blood vessel integrity = vessel wall repairs
- Thrombosis or clot formation
- Controls hemostasis
Size: 2 to 4 μm
Shape: round or oval, anucleate
Granule: slightly granular
- Deep vein thrombosis, pulmonary emboli, acute myocardial infarctions (heart attacks), cerebrovascular accidents (strokes),
peripheral disease, spontaneous abortions (miscarriages)
- Use phase microscopy for easy identification
- Increase platelet count: thrombocytosis (inflammation or trauma)
- Thrombocytopenia: too low
- Essential thrombocypenia - rare malignant condition = extremely high platelet counts and uncontrolled platelet production.
- life threatening hematologic disorder

Blood Film Examination

3 types of blood smear:
- Cover glass smear
- Wedge smear
- Spun smear
- Buffy coat smear for WBCs
- Thick blood smear for blood parasites