General and Special Pathology objectives. Basic terminology, purpose, tasks, methods.
General and Special Pathology objectives
Pathology quite literally comes from ‘Pathos’ (suffering) ‘Logos’ (study), i.e. the study of suffering.
Pathology can be seen as having two main objectives:
- Etiology - causes of disease (why a disease develops)
- Pathogenesis - development of disease in the body (how a disease develops)
General pathology is common changes in all tissues, for instance, all tissues can undergo inflammation, cancer and aging, meanwhile, special pathology looks to examine the etiology and pathogenesis of particular specialized organs, e.g. pneumonia, breast cancer.
It can therefore be said that pathology provides the scientific foundation for the practice of medicine.
Basic terminology, purpose, tasks, methods
Here we will consider some core terms and their meaning in the context of Pathology:
- Disease
- ‘Expression of discomfort due to structural or functional abnormality’
- Disease can be:
- Inflammatory
- Acute/Chronic
- Congenital/Acquired
- Genetic/environmental
- Mild/Moderate/Severe
- Has four aspects
- Etiology (causal agent)
- Pathogenesis (mechanism of change)
- Morphology (structural change)
- Clinical expression
- Death
- Clinical Death (reversible cessation of blood circulation and breathing)
- Biological Death (irreversible)
Example: Tuberculosis through the four aspects: etiology – Mycobacterium tuberculosis; pathogenesis – cell-mediated (type IV) hypersensitivity; morphology – caseating granulomas with Langhans giant cells; clinical expression – chronic cough, haemoptysis, night sweats and weight loss.
The primary methods of Pathology are:
- Autopsy
- Clarifies cause of death and helps improve future treatment
- Two types
- Hospital - for patients that died of natural causes
- Or Forensic - legal case concerned
- Includes External examination, Dissection and Pathology protocol
- Biopsy (tissue from a living patient)
- Histological
- Investigation of tissue, methods include
- Surgery
- Endoscopy
- Large needle biopsy
- Cytological
- Investigation of isolated cells
- May be body fluids, fine needle biopsy or vaginal smears
Other methods in Pathology include
- Electron microscopy
- Immunofluorescence
- Immunohistochemistry
- Molecular pathological methods (e.g. PCR) and others.