Introduction to Pathology And its rule in the diagnostic process Dr. Atif Ali Bashir, MD Pathology Assistant Professor College of Medicine Majma’ah University

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

3 What is Pathology? Greek Pathos = suffering, fate, harm; logos/logia = study or discourse Greek Pathos = suffering, fate, harm; logos/logia = study or discourse Pathology = “The study of suffering.” Pathology = “The study of suffering.” Involves Involves study of disease processes and study of disease processes and the structural and functional changes in organs and tissues that cause or are caused by disease. the structural and functional changes in organs and tissues that cause or are caused by disease. Explains: Explains: The “whys” and “hows” of signs and symptoms manifested by patient. The “whys” and “hows” of signs and symptoms manifested by patient.

What is the Disease? It is the “ It is the “State in which an individual exhibits an anatomical, physiological, or biochemical deviation from the normal” Disease (dis + ease= not at ease). Disease may be defined as :Disease may be defined as : an abnormal alteration of structure or function in any part of the body.

Classification of Diseases:  Developmental – genetic, congenital.  Acquired: *Inflammatory – Trauma, infections, immune, etc. *Neoplastic – tumors cancers *Degenerative – ageing. *Metabolic. *Iatrogenic: Drug induced.

In order for a subject or course to be meaningful, one should become familiar with the basic terminology applicable to that subject. Basic Language of Pathology

Branches of Pathology General Pathology General Pathology Systemic Pathology Systemic Pathology Gross Pathology Gross Pathology Cellular Pathology Cellular Pathology Surgical Pathology Surgical Pathology Clinical Pathology Clinical Pathology Immunopathology Immunopathology

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

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

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

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

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

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

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

pathogenesis The sequence events in the response of the cells or tissues to the etiologic agent, from the initial stimulus to the ultimate expression of the disease,”from the time it is initiated to its final conclusion in recovery or death” The sequence events in the response of the cells or tissues to the etiologic agent, from the initial stimulus to the ultimate expression of the disease,”from the time it is initiated to its final conclusion in recovery or death” The core of the science of pathology — the study the pathogenesis of the disease.

Morphology: Structural Changes Structural changes in disease. Tumor in a cancer. Ulcer in an infection. Atrophy in dementia. Gross & Microscopic.

Clinical Symptoms & Signs Clinical signs are seen only in the living individual. Clinical signs are seen only in the living individual. “Functional evidence of disease which can be determined objectively or by the observer" (fever, tenderness, increased respiratory rate, etc.)” “Functional evidence of disease which can be determined objectively or by the observer" (fever, tenderness, increased respiratory rate, etc.)” Clinical symptoms are the patient’s complain usually by its own words. Clinical symptoms are the patient’s complain usually by its own words.

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 Euthanasia: Intentional putting to death of an individual with an incurable or painful disease by employing humane means

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

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