Pathology Introduction



Your practice of medicine is as good as is your knowledge and understanding of Pathology”. -Sir William Osler


Pathology is the “scientific study of disease”. It is the “scientific study of the molecular, cellular, tissue, or organ system response to injurious agents.” It “is the foundation of medical science and practice. Without pathology, the practice of medicine would be reduced to myths and folklore”.

Pathology serves as a “bridge” or “link” between the preclinical sciences (anatomy, physiology, etc.) and the courses in clinical medicine. It is the study of what is abnormal or wrong or disease…!

This brings us to the question what exactly is disease?

Disease is the “state in which an individual exhibit an anatomical, physiological, or biochemical deviation from the normal”. It may be defined as an abnormal alteration of structure or function in any part of the body.

The word “pathology” comes from the Greek words

“pathos” meaning “disease” and

 “logos” meaning “a treatise” = a treatise of disease. 

As a field of general inquiry and research, pathology addresses four components of disease:

1) Aetiology (cause).

2) Mechanisms of development (pathogenesis)

3) Structural alterations of cells (morphologic changes) and

4) The consequences of changes (clinical manifestations).


Branches of Pathology

  • General pathologydeals with fundamental processes that are common to more than one tissue or organ
  • Systemic pathologyis study of diseases peculiar to certain systems or organs
  • Special pathologyis study of diseases caused by specific microbial pathogens
  • Clinical pathologyis that branch of pathology used in the diagnosis of the diseases in the hospital at the patient’s bedside. Pathology applied to find the solution to clinical problems especially the use of laboratory methods in clinical diagnosis.
  • Comparative pathologyis the study of diseases of animals and comparing them to those occurring in man.
  • Nutritional pathologyis the study of disease processes resulting from deficiency or excess of essential foods
  • Experimental pathologymeans the study of disease artificially produced in animals
  • Chemical pathologydeals with alterations in biochemical processes in diseases
  • Toxicopathologymeans the study of diseases caused by toxic substances
  • Oncologyis study of tumours.



Objectives of studying Pathology are: –

  1. To find out the correct diagnosis and prognosis of diseases, whether it is curable, incurable, medical, surgical etc.
  2. To prevent & cure diseases.
  3. To manage the treatment of the patient suitably with proper diet regimen etc.
  4. The knowledge of Pathology of the disease is necessary to interpret the symptomatology obtained and to prescribe the Similimum.
  5. Finally, to a physician it gives all the information for the treatment and management of the patient.