Introduction to pathology


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This powerpoint will allow you to know about the background of pathology.

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Introduction to pathology

  1. 1. Introduction To PathologyThe Discipline Of Pathology
  2. 2. GOAL• The principal goal of the second yearpathology course in medical schools is tofoster understanding of the mechanismsof disease(pathogenesis) as a foundationfor dealing with a vast amount of clinicalinformation the student will encounter inlater clinical years2
  3. 3. The Principal Objectives• To use pathology to facilitate medicaleducation• understanding mechanisms is more afunction of logic than of a memory• To leave students with a lastingknowledge of pathology• To use pathology as the scientific basisof the” art” of medicine3
  4. 4. What Is Pathology• Pathology literally is the study (logos) ofsuffering (pathos)• Pathology is the scientific study of disease• Pathology is the foundation of medicalscience & practice• Pathology is a bridging discipline devotedto the study of the structure & functionalchanges in cells, tissues & organs thatunderlie diseases4
  5. 5. • Pathology attempts to explore the “ whys” and “wherefores” of the signs and symptoms ofdiseases• Pathology much of it has a visible expressions _Radiographs_CT-scans_MRI (magnetic resonanceimaging) _Ultrasound_Clear drawingsMOLECULAR abnormalities5
  6. 6. History Of Pathology• Era of Medical Antiquitythe early dominance of animismPLATO & PYTHOGORAS• Era of Morbid AnatomyAutopsies performed scientifically fromabout 1500A.D,19thcentury in GermanyROKITANSKY&ASCHOFF6
  7. 7. • The application of MICROSCOPYrevolutionized medicinePasteur’s demonstrationRudolf Virchow (1821-1902)CELLULAR PATHOLOGYThe impact of pathology in the realm ofmolecular changesCancer,Congenital diseases7
  8. 8. The scope of Pathology• Scientific knowledge about human diseases isderived from observations on patients or , byanalogy, from experimental studies on animals &cell cultures.• Clinical medicine is based on a longitudinalapproach to a patient’s illness• Clinical pathology is more concerned with across-sectional analysis at the level of thedisease itself, studied in depth- the cause &mechanisms of the disease, & the effects of thedisease upon the various organs&systems8
  9. 9. Subdivisions of Pathology• Histopathology: the investigation &diagnosis of disease from the examinationof tissues• Cytopathology:the investigation & thediagnosis of disease from the examinationof isolated cells• Haematology:the study of the disorders ofthe cellular & coagulable components ofblood9
  10. 10. • Toxicology: the study of the effects ofknown or suspected poisons• Forensic pathology: the application ofpathology to legal purposes( e.g.investigation of death in suspiciouscircumstances)• Chemical pathology : the study &diagnosis of disease from the chemicalchanges in tissues & fluids10
  11. 11. Techniques Of pathology• Light Microscopy- the structure of tissues& cells in health & disease• Histochemistry- is the study of thechemistry of tissues• Immunohistochemistry- employantibodies( immunoglobulins with antigenspecificity) to visualize substances intissues sections or cell preparations11
  12. 12. • Electron Microscopy- study of disorders atan organelle level, & to the demonstrationof viruses in tissue samples• Biochemical techniques-fluid & electrolytehomeostasis, serum enzyme assayse.g.raised levels of cardiac enzymes inthe blood• Haematological techniques- in thediagnosis & study of blood disorders12
  13. 13. • Molecular Pathology-many advancescome from the relatively new science ofmolecular pathologydefects in the chemical structure ofmolecules arising from errors in thegenome, using IN SITU HYBRIDISATIONe.g.Hg molecule,collagen molecule,alterations in the genome governing thecontrolof cell & tissue growth13
  14. 14. General & Systematic Pathology• General Pathology: is our currentunderstanding of the causationmechanisms ,and characteristics of themajor categories of disease( e.g.congenital versus acquireddiseases,inflammation,tumors,degenerations)• General Pathology is the foundation ofknowledge that has to be laid down14
  15. 15. • Systematic Pathology is our currentknowledge of specific diseases as theyaffect individual organs orsystems( e.g.appendicitis, lung cancer,atheroma).• “Systematic” should not be confused with“Systemic”15
  16. 16. Learning Pathology• There are two apparent difficulties thatface the new student of pathology:LANGUAGE&PROCESS• The student must not confuse thelearning of the language with the learningof the mechanisms of disease and theireffects on individual organs and patientse.g. the term hyperplasia16
  17. 17. • Pathology is learnt through a variety of media-text book-relatively didactic lectures-tutorials-demonstrations( gross & microscopicexamination of diseased tissues)-post – mortem teaching-problem- solving orientated practicalclasses17
  18. 18. • Disease Mechanisms constitute generalpathology• A logical & orderly way of thinking aboutdiseases& their characteristics must becultivated -incidence-etiology-pathogenesis-pathological and clinical features-complications and sequelae-prognosis18
  19. 19. PATHOGENESIS• Refers to the sequence of events in theresponse of the cells or tissues to the etiologicagent, from the initial stimulus to the ultimateexpression of the disease.• The mechanism through which theetilogy( cause) operates to produce thepathological and clinical manifestations.• Examples include: inflammation,degeneration ,carcinogenesis,immune reactions19
  20. 20. Making Diagnoses• Diagnosis is the act of naming a diseasein an individual patient• The process of making diagnosesinvolves: taking a clinical history todocument symptoms,examining thepatient for clinical signs& if necessary,performing investigations guided by theprovisional diagnosis based on signs &symptoms20
  21. 21. Diagnostic Pathology• In living patients we investigate &diagnose their illness by applyingpathological methods to the examinationof TISSUE BIOPSIES& BODY FLUIDS• Biopsies are samples of tissue removedfrom a patient for diagnostic purposes.• Resections specimens are the whole orpart of an organ removed for a previouslydiagnosed condition.21
  22. 22. • Biopsies can be obtained by a variety ofmethods: needle biopsy, endoscopic biopsy andincisional biopsy• Cytology involves the examination andinterpretation of dispersed cells rather than solidtissues,usually for the diagnosis of cancer &pre-cancerous lesions.• These cells can be obtained by a variety ofmethods according to the organ beinginvestigated22
  23. 23. • Exfoliative cytology: cells shed from, or scrapedor brushed off ,an epithelial surface• Fluid cytology :cells withdrawn with the fluid inwhich they are suspended• Washings: cells flushed out of an organ usingan irrigating fluid• Fine –needle aspiration cytology: cells suckedout of a solid tissue using a thin needle attachedto a syringe.23
  24. 24. AUTOPSIES• Autopsy( necropsy and post- mortemexamination are synonymous)• Autopsy means to ‘see for oneself’• Autopsies are used for:-determining the cause of death-audit of the accuracy of clinicaldiagnosis-education of undergraduates &postgraduates24
  25. 25. • Research into the causes andmechanisms of disease• Gathering accurate statistics aboutdisease incidence• There has been a regrettable decline inthe autopsy rate during the latter half ofthe 20thcentury25
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