1. Introduction to Pathology lecture 1 Dr. Nadia Sabry Al-Ani

2. Definition of pathology
Study of disease by Scientific method
"scientific study of the molecular, cellular, tissue, or organ and system response to injurious agents."

3. Pathology as a word means:
The study (logos) of suffering (pathos).

4. Branches of Pathology General Pathology: Systemic Pathology
Study of the Common changes in all tissues. e.g. Inflammation, cancer, ageing, edema, hemorrhage ….etc.
Systemic Pathology
Discussing the pathologic mechanisms in relation to various organ systems e.g. CVS, CNS, GIT.

5. What is the Disease?

6. Abnormal alteration of structure or function in any part of the body.
What is the Disease?
“State in which an individual exhibits an anatomical, physiological, or biochemical deviation from the normal”
Abnormal alteration of structure or function in any part of the body.

7. Classification of Diseases:
Genetically determined diseases: congenital , developmental
Acquired diseases:
*Inflammatory – Trauma, infections, immune,
*Neoplastic – tumors or cancers

8. What should we Know About A Disease
Definition.
Epidemiology – Where & When.
Etiology – What is the cause?
Pathogenesis - Evolution of dis.
Morphology - Structural Changes
Functional consequences
Management
Prognosis
Prevention
Pathology

9. Pathology focuses on 4 aspects of disease:
ETIOLOGY: Cause of disease.
PATHOGENESIS:
Mechanisms of development of disease.
MORPHOLOGY:
The structural alterations induced in cell and tissues.
FUNCTIONAL CONSEQUENCES:
Functional results of the morphologic changes, as observed clinically.

10. How can we Remember & Understand the disease

11. By a morphologic IMAGE
This can be:-
Gross appearance:- By the naked eye.
Microscope :- Light microscopic
Electron microscope
X-ray:- Radiograph
Molecular study:- Genetic, Histochemistry,…
In MOST cases it is: LIGHT MICROSCOPIC

12. Etiology: What is the cause?
Environmental agents:
Physical
Chemical
Nutritional
Infections
Immunological
Psychological
Genetic Factors:
Genes
Multifactorial:
As Diabetes, Hypertension
Cancer

13. Environmental causes of diseases
Physical agents: mechanical injury, heat, cold, electricity, irradiation….etc.
Chemicals & drugs: cyanide, strong acids and alkalins.
Deficiency diseases: e.g. iron deficiency.
Infective M.O. : bacteria, protozoa, fungi and viruses.
Immunological factors: Harmful effects result from the reaction of antibodies and lymphocytes with microbes and their toxic products.
Pscychogenic factors: e.g. schizophrenia and depression
Diseases of addiction: (Alcohol, various drugs, tobacco)

14. Methods used to study pathology:
 1- Histopathology: Examination of the diseased tissues by light or
electron microscope.
2- Cytopathology: Examination of isolated cells for diagnosis of
the disease.
3- Biochemistry: Examination of the metabolic disturbances of
diseases by evaluation of various compounds in
body fluids.
4- Microbiology: Identification of the causative microorganism of
the disease by examination of body fluids,
mucosal surfaces and excised tissues using
microscopical, cultural and serological techniques.

15. Methods used to study pathology Cont.
5- Haematology: Microscopical examination of blood.
6- Cytogenetics: Examination of chromosomal
abnormality.
7- Histochemistry: Detection of cells and tissues
constituents using special
immunohistochemical techniques.
8- Forensic pathology: Examination of tissues taken from
autopsy (dead body).

16. Histochemical stains used in pathology
Hematoxylin & Eosin staining (H &E) :
Hematoxylin:- Strong affinity for nucleus = blue color.
Eosin:- Bind tissue proteins = pinkish discoloration.

17. Demonstrates Glycogen & mucosubstances, Outlines basement membranes.
Special stains
most commonly:-
periodic acid Schiff stain.
(PAS)
It is used to :-
Demonstrates Glycogen & mucosubstances,
Outlines basement membranes.
Makes evident most types of fungi & parasites.

18. Stains for micro- organisms.
These include techniques for gram-positive and gram-negative bacteria, acid-fast mycobacteria, Fungi & parasites.
for example Gram stain, ziehl-Neelsen ( for acid-fast organisms)
Gram stain
ziehl-Neelsen

19. Amyloid stain (congo red) to detect amyloid.

20. Reticulin stains:- used to demonstrate:
- Reticular fiber (type III collagen presents in the
connective tissue throughout the body).
- Basement membranes (type IV collagen and laminin).
- The main use of this stain is in tumor pathology.

21. Giemsa stain:
It is most useful for the demonstration of various
lymphoreticular elements . (Bone marrow smear)

22. I hear, I forget I see, I remember I do, I understand
Chinese Proverb..