INTRODUCTION TO HEMATOLOGY

Hematology (Hema = blood, logy = study) is the study of blood and blood forming organs. Hematology deals with blood physiology as well as pathology.

BLOOD

Blood is a specialized mobile connective tissue that circulate in closed vascular system.
○ The cellular composition of blood was not recognized until the invention of the microscope
○ Leeuwenhoek (1632–1723) accurately described and measured the red blood cells (erythrocytes).
○ The discovery of white blood cells (leukocytes) and platelets (Thrombocytes) followed after microscope lenses were improved.

○ Karl Vierordt (KV) in 1852 published the first quantitative results of blood cell analysis.
○ Improved methods of blood examination described in 1920s.
○ In 1930s allowed anemia’s and other blood disorders to be studied on rational basis.
○ Later it was recognized that alterations in the components of blood are the result of disease.

Blood is composed of a liquid compartment, called plasma and cellular compartment called blood cells.
○ The normal adult has about 6-8 liters of this vital fluid, which composes from 7% to 8% of the total body weight.
○ Plasma makes up about 55% of the blood volume and about 44% of the volume is composed of erythrocytes, and 1% of the volume is composed of leukocytes and platelets.

BLOOD COMPOSITION

Liquid compartment (Plasma/Serum):
○ Water: 92%
○ Plasma Proteins: 7%
○ Albumin Coagulation factors 
○ Globulin: α, β, γ globulin
○ Electrolytes/ions: Na, K, Ca, Cl, Mg, Zn, Cu etc
○ Vitamins: A, B complex, C, D, E and K
○ Fats: TG, Cholesterol, HDL, LDL etc
○ Hormones: Thyroid, Growth, EPO, TPO etc
○ Enzymes: Reductase,oxygenase, phosphorulase

Cellular Compartment:
○ Erythrocytes (Non nucleated)
○ Leukocytes (Nucleated)
○ Thrombocytes (Non nucleated)

Leukocytes are further two types
1. Granulocytes: Contain granules in their cytoplasm
2. A granulocytes: No granules in their cytoplasm

1. Granulocytes are:
○ Neutrophils
○ Basophils
○ Eosinophils

2. A granulocytes are:
○ Monocytes
○ Lymphocytes

» On the basis of morphology Lymphocytes are:
1. Small Lymphocytes
2. Large Lymphocytes
3. Large granular lymphocytes (NK cell)

functions of blood

Plasma functions

○ Major part of plasma is water. It act as solvent and vehicle for the transport of blood cells and other component.
○ Regulation of fluid balance
○ Elimination of waste products
○ Regulation of body temperature
○ Maintenance of electrolyte balance

○ Albumin maintain osmotic pressure and also carrier protein for drugs, hormones, unconjugated bilirubin etc.
○ Coagulation factors: Maintain hemostasis
○ Globulin: Maintaining viscosity, peripheral resistance and blood pressure. It act as buffer by combing with Co2 to formed carbamino compound which help Co2 transportation
○ It is also act as a protein reservoir for new protein synthesis

β globulin is a carrier proteins i-e transfferin, ceruloplasmin, hemopexin and haptoglobins etc
○ Transport of waste product: Urea and creatinine.
○ Transport of nutrients: Glucose, amino acid, lipid, iron, calcium, etc.
○ Transport of hormone (endocrine hormones) and vitamins (Vitamin B complex, K etc ).
○ Maintenances blood pressure by the regulation of heart rate and peripheral resistance while center is in CNS.

Blood cells functions

1. Red blood cells
○ Transportation of oxygen.
○ Removal Co2.
○ Buffer system
○ Maintained of blood viscosity

2. White blood cells
○ Neutrophils combating against bacterial & fungal infections.
○ Lymphocytes major role in viral illness and synthesis of immunoglobulin
○ Eosinophils provide defense against worm infestation and other parasitic infections
○ Basophils causes allergic reaction by releasing histamine. They also contain heparin which is an anticoagulant and serotonin that mediates vasoactive response.
○ Monocytes: are the key cells in phagocytosis; they also play a major role in acquired immune response.

3. Platelets
○ Platelets form primary hemostatic plug and stabilize the secondary hemostatic plug.

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