About basics of pathology- Its definition, terminologies, subdivision & branches and objectives & purpose of pathology study

1. Introduction to Pathology
Vandana Thakur
Ph.D. Research Scholar,
Department of Pharmacology,
LMCP, Ahmedabad

2. Introduction
• The word PATHOLOGY is derived from two Greek words-
‘Pathos’ meaning suffering and ‘logos’ meaning study.
• Pathology is a study of the structural, biochemical and
functional changes in cells, tissues and organs that underlie
disease.
• It serves as a bridge between basic science and clinical
practice.

3. • It involves the investigation of the causes of disease and the
associated changes at the levels of cells, tissues, and
organs, which in turn give rise to the presenting signs and
symptoms of the patient.
• The range of the structural changes is from those affecting
sub-cellular organelles (molecular pathology) up to
alterations seen by the naked eye (gross pathology).

4. Health And Disease
• Health- complete physical, mental and social well being, not
merely an absence of disease.
• Disease- is expression of discomfort due to structural or
functional abnormality.
• Illness- means a condition marked by pronounced deviation
from the normal healthy state.
• Syndrome: (meaning running together) is used for a
combination of several clinical features caused by altered
physiologic processes.

5. Terminology In Pathology
• Patient- is a person affected by the disease.
• Lesion- is characteristic changes in tissue and cells
produced by disease.
• Morphology- is examination of diseased tissue.
• Etiology- is the cause of the disease. (i.e. Why? Of
disease)
• Pathogenesis: Mechanism by which the lesions are
produced. (i.e. ‘how’ of disease).

6. What should we know about a
Disease?
• Definition.
• Epidemiology – Where & When.
• Etiology – What is the cause?
• Pathogenesis - Evolution of disease
• Morphology - Structural Changes
• Functional consequences
• Management
• Prognosis
• Prevention
Studied in
Pathology

7. Etiology
THE ETIOLOGICAL FACTORS ARE: -
• ENVIRONMENTAL FACTORS
• GENETIC FACTORS
• INDIRECT CAUSES
ENVIRONMENTAL FACTORS ARE:
– PHYSICAL AGENTS – Radiation, trauma or mechanical injury, thermal changes,
electrical, nuclear or X-rays, changes in atmospheric pressure
– CHEMICAL AGENTS – Chemicals, poisons like venoms or toxins, corrosive
agents like strong acids and alkalis
– NUTRITIONAL DEFICIENCES AND EXCESSES
– INFECTIONS AND INFESTATIONS - Abnormal immunological reactions
– PSYCHOLOGICAL FACTORS
GENETIC FACTORS: Abnormal genes
INDIRECT CAUSES: Pertain to the predisposing factors like age, sex,
environment, race, climate, state of nutrition, habits

8. Subdivisions of Pathology
Pathology is broadly divided into two categories:
1. General pathology: Deals with general principle of
disease. e.g. inflammation, cancer, ageing.
2. Systemic pathology: Study of disease pertaining to
the specific organs and body systems.
*In general the study of pathology includes morphological and non-
morphological disciplines

9. (Involves application of microscope)
Morphological branches

10. Morphological branches
1. HISTOPATHOLOGY
The study includes structural changes observed by
naked eye examination refered as gross or macroscopic
examination and the changes detected by microscopic which
may be further supported by numerous special staining
methods such as histochemistry and immunohistochemistry
to arrive at the most accurate diagnosis.
It is further divided into
a. Surgical pathology
b. Experimental pathology
c. Forensic pathology and autopsy work

11. a. Surgical pathology: It deals with the study of
tissues removed from the living body by biopsy or
surgical resection. It includes the study of tissue by
paraffin embedding techniques.
Intraoperative frozen section may be employed
for rapid diagnosis.
Morphological branches

12. b. Experimental pathology: (Study of disease in
experimental animal).
This is defined as production of disease in
experimental animals and study of morphological
changes in organs after sacrificing the animals.
Morphological branches

13. c. Forensic pathology and autopsy work: This includes
the study of organs and tissues removed at postmortem for
medicolegal work and for determining the underlying
sequence and cause of death.
These helps the pathologist to reconstruct the course of
events how they may have happened.
Postmortem anatomical diagnosis help the clinician to
enhance his knowledge about the disease and his judgement
While forensic autopsy helpful in medicolegal purposes
Morphological branches

14. 2. CYTOPATHOLOGY:
It includes the study of cells shed off from the lesion (Exfoliative
cytology) and fine needle aspiration cytology (FNAC) of
superficial and deep seated lesions for diagnosis.
3. HAEMATOLOGY:
Deals with the disease of blood. It includes laboratory
haematology and clinical haematology.
Morphological branches

15. (Qualitative, Semi-quantitative and
Quantitative determination )
Non-Morphological branches

16. It includes-
• Clinical Pathology
• Clinical biochemistry
• Microbiology
• Immunology
• Medical genetics
• Molecular pathology
Non-Morphological branches

17. Clinical pathology: Analysis of various fluids
1. Blood
2. Urine
3. Semen
4. CSF and other body fluids
(such analysis may be qualitative, semi-quantitative or quantitative)
Clinical Biochemistry: Quantitative determination of
various biochemical constituents in serum and plasma,
and other body fluids.
Non-Morphological branches

18. Microbiology: Deals with the study of disease
causing microbes implicated in human diseases.
Depending upon the type of Microorganisms
studied, it is further developed into such as
bacteriology, parasitology, mycology, virology etc.
Immunology: Detection of abnormalities in the
immune system of the body.
Non-Morphological branches

19. Medical Genetics: It deals with the relationship between
heredity and disease. There have been important developments
in the field of medical genetics. E.g. blood groups, inborn errors
of metabolism, chromosomal aberrations in congenital
malformations and neoplasms etc.
Molecular Pathology: Detection and diagnosis of abnormalities
at the level of DNA of the cells.
Included in molecular pathology such as insitu-
hybridisation, PCR etc.
Non-Morphological branches

20. Objective and Purpose of
pathological examination
• Diagnosis of disease
• Determining the treatment, prognosis, and
grading.
• Medico-legal conditions, to determine the
cause of death
• Researches and medical discovery

21. Reference
• Harsh Mohan, Textbook of pathology, 7th
Edition.

22. Thank you..!!!