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PATHOLOGY

Dr. Ziyad Ahmed
Goal
The principle goal of the third year pathology course in medical schools is understanding of the mechanisms of disease (pathogenesis) as a foundation of dealing with a fast amount of clinical information the students will encounter in later clinical years
The Principle Objectives
To use pathology to facilitate medical education
Understanding mechanisms is more a function of logic than of a memory
To leave students with lasting knowledge of pathology
To use pathology as the scientific basis of the art of medicine

REQUIRED TEXTS

Basic Pathology Robbins
Pathology Secrets

What Is Pathology

Definition:
Pathos= suffering ------ Disease
Logos = study
Pathology is study diseases by scientific methods.

A disease is an abnormal variation in the structure and/or function of any organ in the body
Examples of diseases
Pneumonia: Inflammation of the lung. There are structural changes in the lung and disturbance of function of respiration

Pathology focuses on 4 aspects of disease

ETIOLOGY:--
Mean the cause of the disease e.g. bacterial infection of the lung causes pneumonia, cut of blood supply by the coronary artery causes infarction of the heart
PATHOGENESIS:--
Mean the mechanism of development of a disease. E.g. in viral infection the virus proliferates inside the cell leading to rupture of the cell. While bacteria release toxin which destroy cells
The core of the science of pathology the study the pathogenesis of the disease.
MORPHOLOGY: --
The structural alterations induced in cells and tissues.
Gross = Changes in the tissue or organ (by the naked eye)
Microscopy = Changes noted under a light microscope
FUNCTIONAL CONSEQUENCES:--
Functional consequences of the morphologic changes, as observed clinically (Signs & Symptoms).
Knowledge of etiology remains the backbone:
Disease diagnosis
Understanding the nature of diseases
Treatment of diseases.

Pathology Subspecialties

*Cellular pathology including
Histopathology:
The excised tissue is examined grossly (by the naked eye ) for any change in size, shape, color,
Microscopic examination by light or electron microscope for any structural changes
Cytopathology:
Smear (i.e. cells put on slides) are examined for any cellular changes. e.g. cervical smear, bronchial brush, sputum cytology
*Forensic pathology
concerned with medicolegal postmortem examinations.
*Microbiology
the study of infectious diseases and their causes. This can be subdivided into bacteriology, virology, mycology and protozology.
Haematology*
the laboratory study of diseases of the blood.
*Chemical pathology or clinical biochemistry
is the study of body chemistry, usually by assaying the levels of substances ( electrolytes, enzymes, lipids, trace elements) in the blood or urine.
*Immunology
is the study of host defenses against external threats in addition to study of autoimmunity.
*Genetics
the study of inheritance of characteristics and of diseases, or predisposition to diseases

Why study pathology?

#A bridging discipline between basic science and clinical practice.
#To understand the mechanisms of symptom production i.e. help in interpretation of signs and symptom of diseases
Understand the biochemical changes#
Provides a reason or rational for treatment choices#
#To intelligently communicate with professional colleagues
So that you can correctly explain things to your patients#
#Recognize the need for self-directed, independent reading of journals, texts and other sources

PATHOLOGY could be defined as the specialty that employs morphological techniques to explain symptoms and signs, to determine the cause of death, to guide therapy, and to predict the evolution of disease.

Terminology

Healing
The process of bringing about resolution of suffering
Physician
An individual skilled in the art of healing
Biopsy
Piece of tissue taken from living body. e.g. gastric biopsy ,colonic biopsy
Autopsy
Piece of tissue taken from dead body during post mortem examination
Autolysis
Digestion of the tissue by its own enzymes
Prognosis
Mean the outcome of the disease. Is it curable or Is it fatal ?

Prevention

When you know the cause & the pathogenesis, you can plan for prevention of the disease by isolation or vaccination .

Types of diseases

Congenital :
mean develop during intrauterine life e.g. congenital heart diseases.
Postnatal :
Mean after birth. e.g. all infections, tumors ...

Causes of diseases

1.Genetically determined:
due to changes in the gene either due to change in the DNA or the number or sites of the chromosomes. e.g. trisomy chromosome 21 in mongolism.
2.Acquired:
due to the effects of the environment.
3.Multifactorial

Causes of acquired diseases

1.Deficiency disease: e.g. Vit.B12 deficiency
2.Infections: e.g. Tonsillitis.
3.Physical agents: e.g. burn. Trauma etc
4.Chemical agents: all toxin , drugs etc.
5.Immunological: e.g. rheumatic fever
6. Psychological causes. e.g. depression.

How to deal with biopsy

The biopsy should be fixed in proper fixative like 10% formalin. put in proper container and sent to the lab.
Note: formalin or any fixative is used to prevent autolysis.

How is pathology detected

Or how do you find it
SEARCH BY USING YOUR CLINICAL SKILLS
Signs & Symptoms
Imaging
Laboratory Testing
Biopsy
Autopsy

Divisions-Pathology General

study basic reactions of cells and tissues to abnormal stimuli that
underlie all diseases - common changes in all tissues; e.g., cancer, aging, inflammation
Systemic
- study of the particular responses of specialized organs and tissues
to well-defined stimuli -specific changes in organs; e.g., goiter, breast cancer.

Examinations

There will be an examination after each chapter and each exam will be comprehensive over the previous exams
The last or final examination, will obviously be comprehensive
Examinations may be composed of short answer, listing, short discussion, multiple choice, or matching type questions.

Classroom Stuff

Students are expected to attend the lectures. The primary purpose of the
lectures is to present and review the most important aspects of the
respective subject material.
The lectures are not intended to be all encompassing in regards to the material.
The student is expected to read the material in the designated textbook.
Classroom Does
Be prepared to learn what a doctor is supposed to know
Ask questions and answer questions
Participate in class









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