Introduction to Pathology.pptx

patho

1. Introduction to Pathology By: - Dr. Addisu Alemu (MD, Assistant professor of pathology)

2. Learning Objective To use pathology to facilitate medical education Understanding mechanisms, in a way which is more of logic than of a memory. To leave students with a lasting knowledge of pathology To use pathology as the scientific basis of the “art” of medicine

3. Definitions Pathology is Latin word: - Patho = disease or suffering; logy = study The study of disease by scientific methods or pathology is the study of disordered function. Disease Dis-ease = lack of ease Abnormal variation in structure or function of part of the body which often originate from alteration of a survival mechanism or respond adequately WHO defines health as as a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity .

4. Terms Symptoms sign Prognosis Prediction of the out come of a disease. That you may need to discuss with the patient or relatives in planning management and follow up works. Syndrome A group of symptoms, signs, laboratory findings, and physiological disturbances that are linked by a common anatomical, biochemical, or pathological history. E.g. AIDS Lesions A circumscribed area of pathologically altered tissue.

5. Introduction Pathology gives explanations of a disease by studying Etiology Pathogenesis Morphologic changes and Functional derangement and clinical manifestation

6. Etiology The study of cause of the disease Primary etiology – known cause Idiopathic – unknown cause Benefits of knowing the etiology Major etiologic factors Genetic Acquired

7. Pathogenesis It is the mechanism through which the etiology produce the pathological and clinical manifestation E.g. pathogenesis of CHF Pathogenesis leads to morphologic changes

8. Morphologic changes Structural alterations in cells or tissues which can be seen Naked eye – gross morphologic changes Or microscope – microscopic changes Morphologic changes are used To diagnose a disease Can lead to functional alteration and to the clinical sign and symptoms

9. Functional derangement and clinical significance. The morphologic changes in the organ influence the normal function of the organ Determine the clinical features Course Prognosis of the disease

10. In summary, pathology studies:- Etiology  Pathogenesis  Morphologic changes  Clinical features & Prognosis of all diseases .

11. Diagnostic techniques Most are based on Morphologic change Histopathology Cytopathology Hematopathology Immunohistochemistry Microbiological examination Biochemical examination Cytogenetic autopsy

12. Sources of sample Biopsy: - taken from a living person to identify the disease FNAC/fine needle aspiration cytology/: - cellular samples are taken through aspiration by a fine(small bore) needle from a living person. Autopsy:- is examination of the dead body sample to identify the cause of death for forensic or clinical purpose.

13. Tissue fixation Sample tissue like biopsy should be immediately fixed by putting it into adequate amount of 10% formaldehyde to Prevent autolysis and bacterial decomposition and putrefaction To coagulate the tissue to prevent loss of easily diffusible substances To fortfy the tissue against the deleterious effect of the various stages in preparation of sections and tissue processing To leave the tissues in a condition which facilitates differential staining with dyes and other reagents

14. Environmental causes of disease Are classified into Physical agents:- like trauma, radiation, extremes of temp., electrical power Chemicals :- cyanide, acids, bases, bleaches, CO, Nutritional deficiencies and excesses :- Infections & infestations Immunological factors Psychogenic factors

15. Genetic causes of disease Hereditary Sporadic Acquired

16. Course of disease The course of a disease in the absence of any intervention is called natural history of the disease. Stages of natural history of a disease Exposure :- to various etiologic agents latency :- period between exposure and biological onset of disease Biological onset of disease :- marks the initiation of the disease process without any sign or symptom. It may remain asymptomatic or subclinical. Incubation (induction) period :- time from exposure to the first clinical sign or symptom Clinical onset:- when clinical sings and symptoms became apparent Natural recovery can occur at any stage in the progression of disease

17. Following clinical onset, disease may follow Resolution without no sequelae Resolution with sequelae / permanent damage Death

18. Reference Mesele Bezabeh et. al, Lecture note, General pathology for health science students, University of Gondar,2005 Robbins and Cotran , Basic.Pathology.8th.Ed Tim D. Spector, John S. Axford ; An introduction to General pathology, 4 th Ed., 1999