LAB+07+HEMATOLOGY

LAB 7: HEMATOLOGY

Overview

• Hematology is the study of blood, comprising:

  • Plasma: The liquid phase.

  • Cellular Phase: Formed elements including:

    • Red Blood Cells (RBCs): Erythrocytes, responsible for oxygen transport.

    • White Blood Cells (WBCs): Leukocytes, involved in immune response.

    • Platelets: Cell fragments essential for blood clotting.

• Use sheep blood for experiments.

  • Mix blood before starting tests.

  • Refer to Section 13.2 in the textbook for basic principles of hematology.

WBC Differential

• Purpose: Count and identify different types of WBCs.

• Use a prepared slide of stained blood smear.

• Procedure:

  1. Observe under low power microscope.

  2. Count each WBC among RBCs (noted visually). Reference wall poster and lab booklet.

  3. Each group member counts 25 cells; total = 100 cells for percentage calculation.

Hematocrit Measurement

• Definition: Ratio of packed RBC volume to total blood volume.

• Procedure:

  1. Use heparinized capillary tube to draw blood.

  2. Seal one end with clay, then centrifuge in microfuge.

  3. Measure hematocrit against scale card.

• Normal Values:

  • Male: 40-54%

  • Female: 37-47%

RBC Count

• Objective: Determine number of RBCs per mL of blood.

• Use Ery-TIC dilution system and hemocytometer for counting.

• Procedure:

  1. Draw blood into a small capillary tube.

  2. Mix with diluent, then use a long capillary tube to load it into hemocytometer.

  3. Count RBCs in designated squares (1, 2, 3, 4, 5) on the hemocytometer grid.

  4. Note that cells on the edge of counted squares can also be included.

  5. Calculate RBC count using dilution factor (e.g., 10,000).

• Normal Values:

  • Male: 4.5-6.0 million/mm3

  • Female: 4.0-5.5 million/mm3

Measurement of Hemoglobin Concentration

• Function: Hemoglobin (Hb) carries oxygen in RBCs.

• Structure: Composed of globin protein and heme molecules, each containing iron.

• Anemia: Reduced oxygen-carrying capacity can be due to low Hb or RBC count.

• Measurement: Use a colorimetric method with a hemoglobinometer.

  • Hemoglobin concentration expressed in g/dL (grams per deciliter).

  • Normal range: 12-18 g/dL.

MCV and MCHC

• Mean Corpuscular Volume (MCV): Volume of individual erythrocytes.

• Mean Corpuscular Hemoglobin Concentration (MCHC): Concentration of hemoglobin in RBCs.

• Relevance: Helps diagnose anemia by evaluating blood oxygen-carrying capacity.

• Calculation of MCV:

  • MCV = (Hematocrit x 10) / RBC count (million/mm3)

• Average MCV Value: 82-92

• Calculation of MCHC:

  • MCHC = (Hemoglobin in g/dL x 100) / Hematocrit

• Average MCHC Value: 32-36

Causes of Anemia

• Categories of Anemia:

  • Macrocytic: High MCV (deficiencies in B12, folic acid).

  • Normocytic: Normal MCV (acute blood loss, bone marrow damage).

  • Microcytic: Low MCV (iron deficiency);

Clotting Mechanism

• Process: Series of chemical and cellular events.

• Visualisation Method: Use of methyl violet stain to view fibrin strands.

• Key Steps:

  • Conversion of prothrombin to thrombin.

  • Thrombin’s role in transforming fibrinogen to fibrin.

  • Fibrin forms around platelet clumps at the damage site to create a clot.

Blood Types

• Components: Red blood cells have specific antigens (A, B, Rh factor).

• Agglutination: Potential reaction when different blood types mix due to antibodies in plasma.

• Blood Type Chart:

  • Type A: Antigen A, Anti-B antibodies

  • Type B: Antigen B, Anti-A antibodies

  • Type AB: Antigens A and B, no antibodies

  • Type O: No antigens, Anti-A and Anti-B antibodies

• Blood Typing Procedure: Add blood to slide, mix with Anti-A, Anti-B, Anti-D, and observe for agglutination.

Disposal Protocol

• Items and Disposal Methods:

  • Vials of blood: Chemical waste in hood

  • Capillary tubes: Sharps

  • Diluted blood: Chemical waste in hood

  • Hemocytometer: Soak in bleach for 10 mins, return to instructor

  • Hemocue cuvette: Soft waste

  • Gloves and gauze: Soft waste

  • Paper contaminated with blood: Soft waste