Introduction to Pathology

Introduction to Pathology

  • Definition of Pathology: Pathology is derived from the Greek words 'pathos' (meaning suffering or disease) and 'logos' (meaning study).

    • Combined, it refers to the scientific study of diseases

    • Focuses on biochemical, structural, and functional changes in cells and tissues affected by diseases.

Importance of Pathology

  • Understanding diseases is pivotal in modern medicine.

    • Goals: To identify the cause of disease.

    • Knowing the cause enables effective therapy and prevention.

    • Groundwork of modern medicine.

Divisions of Pathology

  1. General Pathology:

    • Examines how cells and tissues respond to injurious stimuli.

    • Key topics include:

      • Cellular adaptation to injury

      • Acute inflammation

      • Tissue repair/wound healing

      • Necrosis (cell death)

      • Neoplasia (tumor formation)

  2. Systemic Pathology:

    • Studies systemic changes due to disease.

    • Focuses on major systems:

      • Central nervous system

      • Cardiovascular system

      • Gastrointestinal system

      • Respiratory tract

Historical Perspectives on Pathology

  • Ancient Concepts:

    • Diseases seen as punishment for immoral behavior (supernatural explanations).

    • Early physicians treated disease using magic (divine ancient priests).

    • Modern interpretations link behavior with disease risk (e.g., lung cancer from smoking).

  • Hippocrates and Galen Era:

    • Introduction of the four humors (blood, phlegm, yellow bile).

    • Disease viewed as imbalances among these humors.

  • Shift to Organ Pathology:

    • Advocated by Morgagni, who studied autopsies to assess lesions in specific organs.

  • Molecular Pathology Paradigm:

    • Focuses on DNA changes and the molecular mechanisms of disease.

    • Uses techniques such as polymerase chain reaction and fluorescence in situ hybridization.

Pathological Techniques

  1. Autopsy:

    • Examination of dead bodies to determine cause of death.

    • Involves both external and internal examinations.

    • Two types of autopsy:

      • Hospital Autopsy: For those who died from natural causes in hospital.

      • Coroner's Autopsy: Required in specific cases (e.g., suspicious circumstances, sudden death).

  2. Microscopy:

    • Utilizes light and electron microscopes for cellular pathology.

  3. Histopathology:

    • Studies diseased tissues via biopsies from living patients.

    • Tissues are processed and stained with specific proteins (e.g., hematoxylin and eosin).

  4. Immunohistochemistry:

    • Uses antibodies to identify tissue antigens.

    • Enhances visualization using chromogens, crucial for oncology studies.

  5. Cytopathology:

    • Focuses on studying cellular changes.

    • Includes procedures like Pap smears to detect cervical lesions.

Biochemical and Microbiological Techniques

  • Biochemical Techniques: Tests for renal and liver function, electrolytes, liver enzymes, etc.

  • Microbiology Techniques: Culturing blood to isolate pathogens (bacteria, fungi, viruses).

  • Hematology Techniques: Complete blood count, sickling status, clotting factors.

Definitions and Terminology in Pathology

  • Health (WHO definition): A state of complete physical, mental, and social well-being and not merely the absence of disease.

  • Symptoms: Patient complaints (e.g., headache, diarrhea).

  • Signs: Clinically observed conditions (e.g., fever, pallor).

  • Etiology: Study of the cause of disease.

    • Examples of Causes:

    • Infectious agents (e.g., Plasmodium for malaria), congenital (e.g., Down syndrome), environmental (toxic agents).

  • Pathogenesis: Mechanism by which a disease develops.

  • Complications: Consequences of disease impacting organ function.

  • Prognosis: Prediction of disease outcome.

  • Epidemiology: The study of disease frequency and distribution in populations.

Common Pathological Suffixes and Prefixes

  • Suffixes:

    • -itis: Inflammation (e.g., prostatitis, hepatitis).

    • -oma: Tumor (e.g., leiomyoma, meningioma).

    • -penia: Lack of (e.g., thrombocytopenia).

    • -ectasia: Dilation (e.g., bronchiectasis).

    • -opathy: Disease condition (e.g., neuropathy).

    • -edema: Swelling (e.g., lymphedema).

    • -megaly: Enlargement (e.g., hepatomegaly).

  • Prefixes:

    • pan-: All (e.g., pancytopenia).

    • dys-: Disorderly (e.g., dysplasia).

    • hyper-: Excessive (e.g., hyperemesis).

    • hypo-: Low (e.g., hypoalbuminemia).

    • meta-: Change (e.g., metaplasia).

    • neo-: New (e.g., neoplasm).

Conclusion and Questions

  • Overview of all discussed topics.

  • Preparation for upcoming MCQs, highlighting that all topics will be included in exams.

  • Invitation for questions and discussion.