General Pathology Lesson 1

Study Notes

Pathology combines the Greek words "pathos" (suffering) and "logos" (study), referring to the scientific study of disease and its effects on the body.
It establishes a scientific foundation for medicine by focusing on cellular and molecular changes in diseases.

General Pathology: Covers fundamental principles and mechanisms of disease, including both morphological and non-morphological aspects.
Systematic Pathology: Focuses on diseases related to specific organs and body systems.

Etiology: Investigates the origin of a disease, categorized into primary etiology (known causes) and idiopathic (unknown causes).
Pathogenesis: Describes the sequence of events that lead to the development of a disease.
Morphologic Changes: Examines structural alterations in cells or tissues, classified into:
- Gross changes (visible to the naked eye)
- Microscopic changes (observed under a microscope)
Functional Derangements: Looks at clinical features (signs and symptoms) and prognosis related to diseases.

Histopathology: Study of tissues at the microscopic level.
Cytopathology: Examination of cells from various body tissues.
Hematopathology: Focuses on blood and its disorders.
Immunohistochemistry: Uses antibodies to detect specific antigens in tissues.
Microbiological Examination: Analysis of microbes to identify infectious agents.
Biochemical Examination: Tests for biochemical changes in body fluids.
Cytogenetics: Studies chromosomal alterations.
Molecular Techniques: Involves DNA/RNA analysis for genetic disorders.
Autopsy: Examination after death to understand disease causes.

Biopsy: Obtains tissue samples for analysis, either incisional (part of tissue) or excisional (entire tissue).
Fixation: Uses 10% formaldehyde to preserve tissue and prevent decomposition.
Processing Steps:
- Dehydration: Removes water from tissue using alcohol.
- Clearing: Replaces alcohol with a solvent for embedding.
- Infiltration: Saturates tissue with molten wax for embedding.
- Embedding: Placing tissue in molds with wax.
- Trimming/Sectioning: Cuts tissue into thin slices using a microtome.
- Staining: Adds color to highlight structures.
- Mounting: Places tissue sections on slides with coverslips.
- Labelling: Assigns unique identifiers to sections.

Cytopathology focuses on diagnosing diseases by examining cells from lesions.
Applications include:
- Screening for asymptomatic cancers.
- Diagnosing symptomatic cancers.
- Monitoring cancer patients post-treatment.
Advantages of cytopathology:
- Cost-effective.
- Quick results.
- Non-invasive sampling methods.
Methods include:
- Fine-Needle Aspiration Cytology (FNAC): Obtains cells using a thin needle with imaging guidance for deep lesions.
- Exfoliative Cytology: Examines shed cells from body fluids.
- Abrasive Cytology: Uses tools to dislodge cells from surfaces (e.g., Pap smears).