HEMATOLOGY

Deals with the clinical, morphologic, and laboratory disorders of the blood and the blood forming organs

Study includes the analysis of the concentration, structure and function of cells in the blood; their precursors in the bone marrow; chemical constituents of plasma or serum function of platelets and proteins involved in the hemostasis and blood coagulation.

BLOOD: Heart Arteries Capillaries Veins Heart.

Historical review:

Aristotle and Plato- study of Hemostasis.

2nd century AD- moises Maimonides describes 2 male children who died in excessive bleeding after circumcision.

1658: Swammerdam: discovered erythrocytes.

1674: Anton van Leeuwenhook: discovered microscopes.

1803: Scholein: Hemophilia: love of Hemorrahage

1842: platelets were described

1846: Wharton Jones: distinguished PMN from leukocytes.

1879: Ehrlich: completely classified the leukocytes (basophil, Neutrophils, Monocytes, Lymphocytes).

1905: paul Morawitz: Blood coagulation theory

1930: Quick prothrombin time determination (Coagulation test)

Functions of the Blood:

1. Respiratory

It transports oxygen from the lungs to the tissues and eliminates carbon dioxide from the body tissues to the lungs.

2. Nutritional

It serves as a vehicle for transport of blood materials absorbed from the gastrointestinal tract to the different tissues of the body.

3. Excretion

It pick up metabolic end products of the tissues

4. Buffering action

Through the presence of buffer system, it helps to maintain the acid base equilibrium.

The maintenance of a normal water balance and fluid distribution throughout the body.

Assists in the preservation of an almost neutral reactions in the tissue and selective secretion of soluble substances.

5. Maintenance of constant body temperature

-it distributes the heat produced in active muscles and thus aids in the regulation of body temperature

6. Transportation of hormones and other endocrine secretions

It transports hormones from the glands in which they are produced to the target organs.

7. Body defense mechanism

It promotes body defense against bacterial invasion and disease through the activities of certain leukocytes and immune bodies in the blood stream.

Physical characteristics of Blood

1. In vivo, it is fluid because of a naturally circulating anticoagulants ( heparin)

2. In vitro, it coagulates within 5-10 mins

3. It is red in color due to hemoglobin

4. Volume: 6-8% of the total body weight

Adults: 5-6 or 60-85ml/kg body weight

Neonates: 250-350ml

Terms:

Normovolemia= normal blood volume

Hypovolemia= decreased blood volume

Due to:

Loss of whole blood

Loss of rbc

Loss of plasma

Loss of body water

Hypervolemia: increased blood volume

During excessive fluid intake

During blood transfusion

During IV injection of fluids

Oligemia: total reduction of blood volume (severely loss of blood)

5. Viscosity:

Resistance to flow; stickiness in comparison to distilled water

It is thick and viscous; 3.5-4.5 times thicker than water.

6. Specific gravity

This refers to the density of blood compared with distilled water

Average: 1.055

Whole blood (men) 1.055-1.064

Whole blood (women) 1.052-1.060

Plasma 1.025-1.029

Serum 1.024-1.028

7. Reaction or pH

Slightly alkaline (7.35-7.45)

8. Osmolality

This depends to the number of osmotic particles in the blood

With an approximately 20gm solid/ 100ml of blood

Serum- 281 to 291 mosm/kg H2O

Composition of Blood

-plasma

Liquid portion of unclotted blood

Protein fibrinogen

Pale yellow plasma

Serum

Liquid portion of clotted blood

Without fibrinogen, clotting factors II, V and VIII

Straw colored fluid

With high serotonin content due to breakdown of platelets during clotting

The following can be found in both plasma and serum:

a. 10% chemicals

NPN (Non protein Nitrogen)

Proteins (albumin and globulin)

Carbohydrates ( sugars)

Lipids (cholesterol, triglycerides)

Enzymes

Electrolytes (inorganic/organic constituents)

Minerals

Antibodies and antigens

Others: hormones, gases

b. 90%water

II cellular/ hemocytes/solids- 45%

a. Redblood cells (RBC)

Erythrocytes

Akaryocytes

Erythroplastids

Normocytes

Discoytes

-contains haemoglobin which binds oxygen

b. white blood cells (WBC)

- leukocytes

-leucoplastids

Defend the body against foreign substances

Types:

a. Granular WBC

= Neutrophil, Eosinophil and Basophils

b. Aggranular WBC

= lymphocytes, monocytes

c. Platelets

=thrombocytes

Thromboplastids

-primarily function in the stoppage of bleeding

d. hemoconia or blood dust of muller

III. Gaseous portion

-exchange between oxygen and carbon dioxide o2, co2 and N2

BLOOD COLLECTION:

Correct patient identification

Various collection techniques with precise methodology

Source of blood: Capillary/ Peripheral Blood and venous Blood

Collected in sterile containers

Microsampling

collection of blood from puncture made on skin

blood obtained :

a. capillary blood

b. peripheral blood

c. arteriolar blood

a. Infants