Pathology Overview

Study Notes

Pathology is the scientific study of disease, deriving from Greek words: "pathos" (suffering) and "logos" (study).
It combines basic science and clinical practice, focusing on structural and functional changes in cells, tissues, and organs.

General Pathology: Examines basic cellular and tissue reactions to abnormal stimuli across all diseases.
Systemic Pathology: Describes specific diseases affecting individual organs or organ systems, like appendicitis and lung cancer.

Originated by Rudolf Virchow in the 1800s, stating that all organ injuries begin with structural or molecular alterations in cells.
Key subcellular compartments involved include:
- Nucleus
- Mitochondria
- Endoplasmic Reticulum (ER)
- Golgi apparatus
- Lysosomes
- Cytosol

Etiology: The cause of disease, which can be genetic or acquired (infectious, nutritional, chemical, physical).
Pathogenesis: Sequence of events from cell/tissue injury to disease development.
Pathological Changes:
- Morphological changes: structural alterations detectable via gross examination, biopsy, and microscopy.
- Functional changes: alterations in pathophysiology.
Clinical Significance: Influences normal function and determines clinical symptoms, course, and outcomes (cure, complication, death).

Can occur due to genetic factors, environmental factors, or a combination of both.
Environmental Factors:
- Physical Agents: Trauma, radiation, temperature extremes, electrical injury.
- Chemicals: Toxic substances from drugs and home cleaners (e.g., cyanide, strong acids).
- Nutritional Issues: Deficiencies (e.g., iron deficiency anemia) and excesses (e.g., obesity leading to heart disease and high blood pressure).
- Infections:
  - Viral (e.g., poliomyelitis)
  - Bacterial (e.g., diphtheria, tetanus)
  - Fungal (e.g., candida)
  - Protozoal (e.g., malaria)
- Immunological Factors:
  - Hypersensitivity reactions (e.g., bronchial asthma).
  - Immunodeficiency conditions (e.g., AIDS).
  - Autoimmunity (self antigen attack).

Homeostasis: Cells maintain normal structure and function and can adapt in response to physiological demands.
Possible outcomes when exposed to injurious agents:
- Adaptation
- Reversible injury (restoration upon removal of stress)
- Irreversible injury leading to cell death via necrosis or apoptosis.

Hypertrophy: Increase in cell size, leading to larger organs, can be physiological (e.g., athletes) or pathological (e.g., cardiac hypertrophy in hypertension).
Atrophy: Decrease in cell or organ size due to loss of cell substance, concepts include:
- Decreased workload (e.g., immobilization).
- Denervation (e.g., paralysis).
- Ischemia (e.g., brain atrophy with aging).
- Inadequate nutrition.
- Loss of endocrine stimulation.
Hyperplasia: Increase in cell number in an organ or tissue, can occur due to various stimuli but specifics not provided in the text.