Introduction to Pathology & Pathology of Inflammation 2009

8/14/2019 Introduction to Pathology & Pathology of Inflammation 2009

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Introduction of

pathology By

Dr. amira kamal El-HawaryDr. AZZa Abdel-AZiZ A. Ali


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You all have studied and understoodthe broad contents of following

subjects Anatomy Histology Biochemistry Physiology

Beginning this semester.you need to add

pathology


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Introduction to

pathology

What is pathology?

Who is a pathologist?

What is a disease?

How are diseases diagnosed?


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Introduction Pathology is the science whichdeals with the study of

diseases.

Pathology(Gr.pathos" disease+ logos "word, reason(


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The Tree of Medicine

(After G. Diamandopoulos(

Pathology isthe study of

the linksbetweendiseases and

the basicscience


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introduction

Pathologistis a person identifyingdiseases based on the examinationof cells and tissues removed from

the body


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What is a Disease?

A disease is a physicalor functionaldisorder of normal body systemsthat places an individual at increased risk of adverse consequences

Diseases are diagnosedby physicians or other health care providersthrough a combination of tools

When a disease is diagnosed, treatmentis given to prevent

complications and to improve prognosis


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Diagnosis)Gr. diathrough +gnosis knowledge(

Diagnoses are made by three general categories of physicians or

health care providers:

Clinical diagnosticiansidentify diseases by examination ofpatients history and physical examination

Pathologistsidentify diseases by examining cells and tissuesremoved from the body

Radiologistsidentify diseases by imagingthe intact body


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Pathology focuses on 4Pathology focuses on 4

aspects of diseaseaspects of diseaseETIOLOGY:ETIOLOGY:Cause of diseaseCause of disease..PATHOGENESISPATHOGENESIS::

Mechanisms of development of diseaseMechanisms of development of disease..

MORPHOLOGY:MORPHOLOGY:The structural alterations induced in cell and tissuesThe structural alterations induced in cell and tissues..

FUNCTIONAL CONSEQUENCESFUNCTIONAL CONSEQUENCES::

Functional consequences of the morphologic changes, as observedFunctional consequences of the morphologic changes, as observed

clinicallyclinically..Knowledge of etiology remains the backboneKnowledge of etiology remains the backbone::

Disease diagnosesDisease diagnosesUnderstanding the nature of diseasesUnderstanding the nature of diseases

Treatment of diseasesTreatment of diseases..


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I-Etiology: This means the causes of the disease.includes:i- Predisposing factors:

I.e. factors which help development of thedisease.ii-Exciting factors:Is the direct cause of the disease (i.e. causelesion(.


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Causes of diseaseCauses of disease Oxygen deprivation ( hypoxia, ischemia)Oxygen deprivation ( hypoxia, ischemia) Nutritional imbalancesNutritional imbalances

Physical agentsPhysical agents

Chemical agents and drugsChemical agents and drugs

Infectious agentsInfectious agents

Immunologic reactionsImmunologic reactions

Genetic derangementsGenetic derangements


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The core of the science ofThe core of the science of

pathology the study thepathology the study the

pathogenesis of the disease.pathogenesis of the disease.


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II Pathogenesis:

The mechanisms by which the causative

agent produce the pathologicalchanges in the tissues,


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III Morphologystructural alterations in cells and

tissues Gross = Changes in the tissue ororgan

Microscopy = Changes noted undera light microscope


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Normal Lung Normal Lung

cut surface

Gross appearance of lungs

Normal & Cut surface

i


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ross appearance o ung indiseases

Pneumonia Lung Tumor


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Gross appearance of

heart in diseases Normal heart Hypertrophied heart


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Microscopy Histologic and cytologic observationunder a light microscope

most common and basic formalin fixed HE (hematoxylin and eosin) stained


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MicroscopyNormal Lung Pneumonia


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Pathological investigation

I- Biopsy: Is the study of a specimen fromthe lesion during life.

II- Autopsy: Is post-mortem examination ofthe cadaver.The materials obtained are put immediately

in fixative fluid to prevent its autolysis.This fluid is commonly 10% formalin.

III Ultrastructural observation


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III Ultrastructural observation

(electron microscope)

Ultrastructural observation


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IV-ImmunohistochemistryAntigen -antibody specific reaction that

use antibodies to various constituents ofhuman cells and their products which help in

clinical diagnosis and distinguishingdiagnosis of tumor histogenesis


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V-Molecular biology

technique1. Polymerase chain reaction (PCR)

2. DNA sequencing


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Additional termsPrognosis: Is the forecast of the course &termination of a disease.

Complications: Are additional pathologicalchanges which may occur during or afterthe termination of the usual course of thedisease. Thus affecting or modifying the

prognosis of the disease.


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So then, what is the

importance of Pathology?Every disease has a

pathological base


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INFLAMMATIONDefinition:It is a response of living tissue to injurious agent.The response consists of a series of vascular, lymphatic

and local tissue changes.

Aim of inflammation: :1. Destroy, dilute, remove or localize injurious agents.2. replacement of the damaged tissue by a new healthy

one..


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Causes of inflammation

The injurious agents which cause inflammation arecalled irritants, these may be:

(A) Living irritantsBacteria, viruses, fungi and parasites.

(B) Non living irritants: Include i- Physical irritants ii- Chemical irritants

iii- Necrotic tissue iv- Immune mechanism (Ag/Ab reaction)


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Types of inflammation

According to the onset, severity and duration of irritation, it isclassified into:

(1) Acute inflammation:- It is of sudden onset, short duration.- Caused by strong irritant e.g. abscess caused by staphylococci

(2) Chronic inflammation:- It is of gradual onset, longer duration.- Caused by mild persistent irritant e.g. TB


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abscess


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Morphological changes in acute inflammation

1) Vascular changes.II) Exudative changes.

III) Local tissue changes.


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I. Vascular changes

A) Changes in the caliber (diameter) of the blood vessels:-Transient vasoconstriction of the arterioles lasting for few seconds.-Permanent vasodilatation:B) Changes in the vascular wall:

Increase vascular permeability

C) Changes in the blood flow:i-The vasodilatation is accompanied by temporary acceleration of

blood flow.

ii-This is followed later by gradual slowing


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II- Exudative phenomenon

(A) Fluid component (fluid exudate)Accumulation of extra cellular fluid at the area ofinflammation to dilute the irritant specially chemicaland bacterial toxins. It brings antibodies to the siteof inflammation

(B) Cellular component (cellular exudate)

escape of leucocytes (neutrophils, macrophages)outside

the circulation for destruction of microorganisms andnecrotic debris.


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Fluid and cellular

exudate
http://imageshack.us/


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III-LOCAL TISSUE

CHANGES The irritant is at a maximum concentration in

the center of the inflammatory area where it

produced necrosis ( death of group of cells). In the surrounding area, it is of lesserintensity producing degeneration (sick cell).

Necrotic cells and degenerated cells release

chemical substances called chemicalmediators which help the vascular changes.


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CHRONIC INFLAMMATION

Definition:It is inflammatory process in which lymphocytes,plasma cells and macrophages predominate and

which is accompanied by fibrosis.

Causes: chronic inflammation may arise in one oftwo ways:

It may follow acute inflammation. Chronic almost from the onset.


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General features of chronicinflammation

-The irritant is mild and has a prolonged action.

-Onset is gradual and duration is prolonged.

-Initial tissue necrosis may not be marked.

-Vascular phenomenon is less marked than in acuteinflammation.

-Fluid exudate is not marked.

-Cellular exudate consists of: lymphocytes, plasmacells, macrophages and giant cells forminggranuloma


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Documents

Introduction to Pathology & Pathology of Inflammation 2009