Introduction to PathologyIntroduction to Pathology And its rule in the And its rule in the diagnostic processdiagnostic process

Dr: Wael H.MansyDr: Wael H.Mansy, MD, MDAssistant ProfessorAssistant Professor

College of Pharmacy College of Pharmacy

King Saud UniversityKing Saud 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 Pathology serves as a ""bridgebridge"" or or ""linklink" " between between

the preclinical sthe preclinical sciencesciences ( (anatomy, physiology, anatomy, physiology, …………

etcetc.) and the courses in clinical medicine..) and the courses in clinical medicine.

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 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:

DevelopmentalDevelopmental – genetic, congenital. – genetic, congenital.

Acquired:Acquired:

*Inflammatory*Inflammatory – Trauma, infections, immune, etc. – Trauma, infections, immune, etc.

*Neoplastic*Neoplastic – tumors cancers – tumors cancers

*Degenerative*Degenerative – ageing. – ageing.

*Metabolic*Metabolic..

*Iatrogenic: Drug induced*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 PathologyBranches of Pathology

General PathologyGeneral PathologySystemic PathologySystemic PathologyGross PathologyGross PathologyCellular PathologyCellular PathologySurgical PathologySurgical PathologyClinical Pathology Clinical Pathology ImmunopathologyImmunopathology

General PathologyGeneral Pathology

Common changes in all tissues. e.g.. Inflammation, Common changes in all tissues. e.g.. Inflammation,

cancer, ageing, edema, hemorrhage ….etc.cancer, ageing, edema, hemorrhage ….etc.

Systemic Pathology Systemic Pathology

Discussing the pathologic mechanisms in relation to Discussing the pathologic mechanisms in relation to

various organ systems e.g. CVS, CNS, GIT…..etc.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:ETIOLOGY: CauseCause of disease. of disease.

PATHOGENESIS:PATHOGENESIS:

MechanismsMechanisms of development of disease. of development of disease.

MORPHOLOGY:MORPHOLOGY:

The The structural alterationsstructural alterations induced in cell and induced in cell and

tissues.tissues.

FUNCTIONAL CONSEQUENCES:FUNCTIONAL CONSEQUENCES:

Functional results of the morphologic Functional results of the morphologic

changes, as observed changes, as observed clinicallyclinically..

Knowledge of Knowledge of etiologyetiology remains the remains the

backbone of:backbone of:

Disease Disease diagnosisdiagnosis

Understanding Understanding the nature of diseasesthe nature of diseases

Treatment Treatment of diseases.of diseases.

Etiology Etiology “Study of the cause of a disease"“Study of the cause of a disease"

Etiology Etiology “Study of the cause of a disease"“Study of the cause of a disease"

An etiologic agentAn etiologic agent : :

is the factor (bacterium, virus, etc.) responsible for lesions or a is the factor (bacterium, virus, etc.) responsible for lesions or a

disease state.disease state.

Predisposing Causes of Disease:Predisposing Causes of Disease:

Factors which make an individual more susceptible to a Factors which make an individual more susceptible to a

disease (damp weather, poor ventilation, etc.)disease (damp weather, poor ventilation, etc.)

Exciting Causes of Disease:Exciting Causes of Disease:

Factors which are directly responsible for a disease (hypoxia, Factors which are directly responsible for a disease (hypoxia,

chemical agentschemical agents….…. etc.).  etc.). 

•One One etiologic agent etiologic agent several several diseases, as diseases, as smoking.smoking.

Disease

• Several etiologic Several etiologic agents one agents one disease, as disease, as diabetes .diabetes .

Disease Disease

DiseaseDisease

One etiologic One etiologic agent agent - - one disease, as one disease, as Malaria.Malaria.

EtiologyEtiology

Environmental agents:Environmental agents:• PhysicalPhysical• ChemicalChemical• NutritionalNutritional• InfectionsInfections• ImmunologicalImmunological• PsychologicalPsychological

Genetic Factors:Genetic Factors:• AgeAge• GenesGenes

Multifactorial:: As Diabetes, As Diabetes,

HypertensionHypertension CancerCancer

Etiology: Etiology: What is the cause?What is the cause?

pathogenesispathogenesis

The sequence events in the response of the The sequence events in the response of the

cells or tissues to the etiologic agent, from the cells or tissues to the etiologic agent, from the

initial stimulus to the ultimate expression of initial stimulus to the ultimate expression of

the disease,”the disease,”from the time it is initiated to its from the time it is initiated to its

final conclusion in recovery or death”final conclusion in recovery or death”  

The core of the science of The core of the science of pathology pathology —— the study the the study the

pathogenesis of the disease.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 & SignsClinical Symptoms & Signs

Clinical signs are seen only in the living Clinical signs are seen only in the living

individual.individual.

““Functional evidence of disease which can be Functional evidence of disease which can be

determined objectively or by the observer" (determined objectively or by the observer" (feverfever, ,

tendernesstenderness, increased respiratory , increased respiratory raterate, etc.)” , etc.)”

Clinical sClinical symptoms ymptoms are are the patient’s the patient’s

complain usually by its own words.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

prognosisprognosis

Expected outcome of the disease, Expected outcome of the disease, It is the It is the

clinician's estimate of the severity and clinician's estimate of the severity and

possible result of a disease. possible result of a disease. 

I hear, I forgetI hear, I forget

I see, I rememberI see, I remember

I do, I understandI do, I understandChinese Proverb..Chinese Proverb..