Introduction to Pathology

Study Notes

Pathology is the study of disease, derived from Greek words meaning "experience" or "suffering" and "study of".
It's vital in medical diagnosis and research, focusing on the causes of diseases, whether infectious or physiological.
Pathology studies how healthy organs and tissues change in disease.
This involves examining surgically removed organs, tissues (biopsies), bodily fluids, or even whole bodies (autopsies).

General Pathology: Focuses on the basic reactions of cells and tissues to abnormal stimuli, underlying all diseases.
Systemic Pathology: Examines the pathological aspects of diseases affecting specific tissues or organs (body systems).

This is a specialization concerned with diagnosing illnesses by examining organs, tissues, and the whole body (like in an autopsy), using methods like gross (naked-eye), microscopic, chemical, immunological and molecular assessments.

Definition and categorization of disease: The identification and classification of diseases.
Etiology: The cause or causes of a disease.
Pathogenesis: The mechanisms of how a disease develops.
Morphological changes (pathological features):
- Gross changes: Observable changes detectable by the naked eye, like size, colour, and consistency changes.
- Microscopic changes: Cellular and extracellular changes visible under a microscope, useful for disease identification and understanding the cause.
Functional consequences: The effects of morphological changes, including clinical symptoms, eventual outcome (fate), disease prognosis, and potential complications.

It uses microscopic examination of tissues to diagnose diseases, often from biopsies or surgical samples.
Examination begins with preparing tissue samples and staining them for better visualization.
Histochemistry: This is the science of using chemical processes to reveal cellular components and details within tissues.

Reversible cell injury (degeneration): Early stages of cell damage that can potentially be reversed.
Irreversible cell injury:
- Necrosis: Cell death resulting from injury or lack of blood supply.
- Apoptosis: Programmed, controlled cell death.
Cellular adaptations: Changes in cell growth and differentiation, such as atrophy (shrinkage), hypertrophy (enlargement), hyperplasia (increased cell number), and metaplasia (change in cell type).
Intracellular accumulations: Buildup of abnormal substances within cells (e.g., fat, proteins).
Extracellular depositions: Buildup of materials outside cells (e.g., calcium).
Inflammation and repair processes: The body's response to injury or damage.
Vascular disturbances: Changes in blood vessels (thrombosis, edema).
Cell growth abnormalities:
- Dysplasia: Abnormal cell growth but not yet cancerous.
- Neoplasia (tumors): Uncontrolled cell growth (can be benign or cancerous).