III lecture

Lecture Overview

  • Complete Blood Count (CBC): Examination of leukocytes, white blood cell differential, neutrophils, eosinophils, basophils, lymphocytes, monocytes, thrombocytes, erythrocyte sedimentation rate, and bone marrow examination. Includes understanding normal physiology and pathology. (Pages 531-539; 606-659)

Instructor Information

  • Professor Mzia Tsiklauri, Doctor of Medicine

White Blood Cells (Leukocytes)

  • White blood cells, or leukocytes, are nucleated and independently motile, playing a crucial role in the body's defense mechanisms.

  • Unlike red blood cells, leukocytes do not undergo mitosis in the bloodstream.

  • Normal range: 4,500 to 11,000 white cells per cubic millimeter, fluctuating with physical activity.

Types of White Blood Cells

Granulocytes

  • The most numerous type of white cells, larger than red cells, about 12-15 μm in diameter.

  • Types of Granulocytes:

    • Neutrophils: 50-80% of leukocytes, involved in phagocytosis of bacteria and fungi.

    • Eosinophils: Less than 3%, involved in killing parasites and allergic responses.

    • Basophils: Least numerous, involved in inflammation and allergic reactions.

Neutrophils

  • Characterized by a multilobed nucleus and pink-stained granules.

  • Typically live for only a few hours but are produced daily at a high rate (100 billion).

  • Neutrophils use chemotaxis to migrate to infection sites and are phagocytic, enclosing pathogens in vacuoles.

Conditions Related to Neutrophils

  • Neutropenia: Defined as less than 0.5 x 10^9 /L, increasing the risk of infection.

  • Kostmann’s syndrome: A congenital form of severe neutropenia.

Eosinophils

  • Similar in size to neutrophils but contain larger granules.

  • Involved in responses to parasites and in allergic reactions.

  • Eosinophilia is diagnosed when eosinophil count exceeds 0.35 to 0.5 x 10^9 /L.

Basophils

  • Involved in allergic responses, releasing histamine and leukotrienes.

  • Basophilia is an increase in basophils often related to allergic reactions or blood disorders.

Monocytes

  • Largest blood cells, averaging 15-18 μm in diameter, accounting for 7% of leukocytes.

  • They can ingest infectious agents and develop into tissue macrophages.

Lymphocytes

  • Comprising 28-42% of white blood cells, essential for adaptive immunity.

  • T Cells: Involved in cell-mediated immunity.

  • B Cells: Function in humoral immunity, producing antibodies.

Blood Cell Development

  • Arises from stem cells in the bone marrow, with differentiation into granulocytes, monocytes, and lymphocytes.

  • Thrombocytes (platelets) play a crucial role in hemostasis and are formed from megakaryocytes in the bone marrow.

Bone Marrow Examination

  • Used to diagnose conditions such as leukemias and lymphomas.

  • Involves obtaining samples through aspiration or biopsy for further analysis and diagnosis.

Risks Associated with Bone Marrow Examination

  • Minor pain or discomfort might occur, but severe complications are rare.