1. Dear Student,
Welcome to the exciting & fascinating world of
pathology! Up to now in your studies, you
have been learning the normal features of human beings (i.e. anatomy, physiology, etc...).
Now it is time to introduce you to the abnormalities that can occur in humans – i.e. to
diseases. Pathology is a scientific study of diseases. In this course, you will learn the basic
mechanisms of diseases.

2. INTRODUCTION TO PATHOLOGY

3. 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 .

4. Diseases may, in turn, be defined as an abnormal variation in structure or function of
any part of the body. Pathology gives
explanations of a disease by studying the
following four aspects of the disease.
1. Etiology: the cause of the disease.
2. Pathogenesis: the cause operates to produce the pathological and clinical manifestations.

5. 3. Morphologic changes: The morphologic changes refer to the structural alterations in cells or tissues that occur following the pathogenetic mechanisms
4. Functional derangements and clinical significance: The morphologic changes in the organ influence the normal function of the organ. By doing so, they determine the clinical features (symptoms and signs), course, and prognosis of the disease.

6. The knowledge and understanding of pathology is essential for all would be doctors and general practitioners. Unless they know the causes and mechanism of disease and understand the language spoken by the pathologists in the form of laboratory reports. They would not be able to institute appropriate treatment or suggest preventive measures to the patient.

7. HEALTH AND DISEASE:
Health: complete physical, mental and social wellbeing, not merely an absence of disease.
Disease: is expression of discomfort due to structural or functional abnormality.
Illness: is the reaction of individual to disease in the form of symptoms.

8. TERMINOLOGY IN PATHOLOGY:
Patient: is a person affected by the disease.
Lesion: is characteristic changes in tissue and cells.
Morphology: is examination of diseased tissue.
Aetiology: is the cause of the disease.
Pathogenesis: is the mechanism by which the disease is produced.
Physical signs: are the functional implications of the disease felt by the patient.

9. Pathology is broadly divided into two categories: 1
Pathology is broadly divided into two categories: General pathology: deals with general principle of disease, covers the basic mechanisms of diseases, E.g. inflammation, cancer, ageing, Cell injury, Healing, Hemodynamic disorders, Genetic diseases, Immunopathology, Metabolic diseases, & Selected infectious diseases.

10. Most of these topics represent the major categories of diseases that can occur in different organ systems. For example, acute inflammation can occur in different organs but wherever it occurs its mechanism is the same. That is, an acute inflammation in the skin has the same mechanisms & features as an acute inflammation of the meninges.

11. The same principle applies to the other topics covered in general pathology. Therefore, general pathology can be applied this knowledge to diseases in the various organ systems.

12. Hence, the general pathology knowledge will facilitate the understanding of systemic diseases (Systemic Pathology).
Therefore, the whole purpose of general pathology is to understand systemic diseases – i.e. Systemic Pathology.

13. 2. Systemic pathology:
covers diseases as they occur in each organ system, Study of disease pertaining to the specific organs and body systems.

14. It is further divided in to following branches: 1. HISTOPATHOLOGY: a
It is further divided in to following branches: 1. HISTOPATHOLOGY: a. gross or macroscopic examination b. microscopic examination. It is further divided in to: a. Surgical pathology b. Forensic pathology i.e .autopsy

15. 2. CYTOPATHOLOGY: a. Exfoliative cytology. b. FNAC
3. HAEMATOLOGY: deals with the disease of blood and blood related components.
4. MICROBIOLOGY: deals with the study of microorganisms.
5. CHEMICAL PATHOLOGY: analysis of biochemical constituent of blood, urine, semen, CSF etc.
6.IMMUNOLOGY detection of abnormalities in the immune system of the body.

16. 7. EXPERIMENTAL PATHOLOGY : study of disease in experimental animal
8. GEOGRAPHIC PATHOLOGY : study of diseases in populations in different parts of world.
9.MEDICAL GENETICS: it deals with the relationship between heredity and disease.
10.MOLECULAR PATHOLOGY: Detection and diagnosis of abnormalities at the level of DNA.