1. Introduction to Pathology DR:Gehan mohamed

2. Definition of pathology
It is the “Scientific study of disease" .
"scientific study of the molecular, cellular, tissue, or organ system response to injurious agents."
Pathology serves as a "bridge" or "link" between the preclinical sciences (anatomy, physiology, ……etc.) and the courses in clinical medicine.

3. 2. Classification: Autopsy Biopsy (1) Human pathology Cytology
(2) Experimental pathology

4. Seven Branches of Pathology
General Pathology
Systemic Pathology
Surgical Pathology
Gross Pathology
Cellular Pathology
Clinical Pathology
Immunopathology 4

5. General Pathology
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…..etc.

6. Techniques of Pathology
1. Human pathology
(1) Autopsy
(2) Biopsy
(3) Cytology: smear, fine needle aspiration
2. Experimental pathology
(1) Animal experiment: animal model
(2) Tissue and cell culture

7. Necropsy: Gross examination of the animal cadaver by systematic dissection in order to evaluate any abnormal changes (lesions) that may be present.
Autopsy: Synonymous to necropsy in human medicine
Biopsy: Removal and examination of tissue obtained from the living body

8. What is the Disease?
It is the “State in which an individual exhibits an anatomical, physiological, or biochemical deviation from the normal”
Disease may be defined as :
an abnormal alteration of structure or function in any part of the body.

9. Classification of Diseases:
(A)Developmental – genetic, congenital.
(B)Acquired:
(1)Inflammatory – Trauma, infections, immune, etc.
(2)Neoplastic – tumors cancers
(3)Degenerative – ageing.
(4)Metabolic.
(5)Iatrogenic: Drug induced.

10. 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

11. Etiology “Study of the cause of a disease"
Knowledge of etiology remains the backbone of:
Disease diagnosis
Understanding the nature of diseases
Treatment of diseases.

12. Etiology “Study of the cause of a disease"
An etiologic agent :
is the factor (bacterium, virus, etc.) responsible for lesions or a disease state.
Predisposing Causes of Disease:
Factors which make an individual more susceptible to a disease (damp weather, poor ventilation, etc.)
Exciting Causes of Disease:
Factors which are directly responsible for a disease (hypoxia, chemical agents , virus, bacteria …. etc.). 

13. Etiology Disease Disease Disease
One etiologic agent several diseases, as smoking.
One etiologic agent one disease, as Malaria.
Several etiologic agents one disease, as cancer .

14. Pathogenesis
The sequence of events in the response of the cells or tissues to the etiologic agent, from the initial stimulus to the ultimate expression of the disease. 35

15. CELLS Response to injurious agent
Either :
ADAPTING
SUSTAINING REVERSIBLE INJURY
SUFFERING IRREVERSIBLE INJURY AND DYING 32

16. Clinical Symptoms & Signs
Clinical symptoms are the patient’s complain usually by its own words as pain.
Clinical signs are seen only in the living individual as organomegaly.

17. MORPHOLOGY Morphology remains at the heart of diagnostic pathology.
Morphologic change
Characteristic of the disease
Diagnostic of the etiologic process
Functional derangements 37

18. Morphology (1)Gross appearance: size, shape weight color consistency
surface
edge, section

19. (2)Microscopic examination for tissue sections fixed in formalin then stained by
HE (hematoxylin and eosin) to be examined by light microscope for Histologic and cytologic changes.
Hemangioma

20. Histochemistry using PAS stain
PAS→BM

21. Immunohistochemistry
1. Ag-Ab specific reaction
2. Applications : in diagnosis of tumor histogenesis

22. Leiomyosarcoma
Actin (+)

23. (3)Ultrastructural observation
By using electron microscope)
Filtering membrane

24. SEM (scanning electron microscope)
Podocyte

25. (4)Flow cytometry (FCM)
In neoplastic diseases Can determine :
1- If there is One kind of cells→quantitative assesment
2. DNA ploidy analysis (amount of DNA)

26. （5）Image analysis (IA)
it can determine Nuclear diameter; circumference; area; volume; morphology

27. （6）Molecular biology technique
1. Polymerase chain reaction (PCR)
2. DNA sequencing

28. Polymerase chain reaction (PCR)

29. prognosis
Expected outcome of the disease, It is the clinician's estimate of the severity and possible result of a disease.