Page 17 - Textbook of Pathology, 6th Edition

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Section I GENERAL PATHOLOGY AND

BASIC TECHNIQUES CHAPTER 1

Chapter 1
Chapter 1 Introduction to Pathology

STUDY OF DISEASES A term commonly confused with disease is illness. While Introduction to Pathology
disease suggests an entity with a cause, illness is the reaction
DEFINITION OF PATHOLOGY of the individual to disease in the form of symptoms
(complaints of the patient) and physical signs (elicited by
The word ‘Pathology’ is derived from two Greek words—pathos the clinician). Though disease and illness are not separable,
meaning suffering, and logos meaning study. Pathology is, thus, the study of diseases is done in pathology while the learning
scientific study of structure and function of the body in disease; and management of illnesses is done in wards and clinics.
or in other words, pathology consists of the abnormalities that In addition to disease and illness, there are syndromes
occur in normal anatomy (including histology) and physiology (meaning running together) characterised by combination
owing to disease. Another commonly used term with reference of symptoms caused by altered physiologic processes.
to study of diseases is ‘pathophysiology’ comprised by two words:
patho=suffering; physiology=study of normal function. TERMINOLOGY IN PATHOLOGY
Pathophysiology, thus, includes study of disordered function
or breakdown of homeostasis in diseases. Pathologists are the It is important for a beginner in pathology to be familiar
diagnosticians of disease. Therefore, knowledge and with the language used in pathology:
understanding of pathology is essential for all would-be doctors, Patient is the person affected by disease.
general medical practitioners and specialists since unless they Lesions are the characteristic changes in tissues and cells
know the causes, mechanisms, nature and type of disease, and produced by disease in an individual or experimental
understand the language spoken by the pathologist in the form animal.
of laboratory reports, they would not be able to institute Pathologic changes or morphology consist of examination
appropriate treatment or suggest preventive measures to the of diseased tissues.
patient. For the student of any system of medicine, the discipline Pathologic changes can be recognised with the naked
of pathology forms a vital bridge between initial learning phase
of preclinical sciences and the final phase of clinical subjects. eye (gross or macroscopic changes) or studied by microscopic
examination of tissues.
Remember the prophetic words of one of the eminent founders
of modern medicine in late 19th and early 20th century, Sir Causal factors responsible for the lesions are included
William Osler, “Your practice of medicine will be as good as in etiology of disease (i.e. ‘why’ of disease).
your understanding of pathology.” Mechanism by which the lesions are produced is termed
pathogenesis of disease (i.e. ‘how’ of disease).
HEALTH AND DISEASE Functional implications of the lesion felt by the patient
Before there were humans on earth, there was disease, albeit in are symptoms and those discovered by the clinician are the
early animals. Since pathology is the study of disease, then what physical signs.
is disease? In simple language, disease is opposite of health i.e. Clinical significance of the morphologic and functional
what is not healthy is disease. Health may be defined as a changes together with results of other investigations help
condition when the individual is in complete accord with the to arrive at an answer to what is wrong (diagnosis), what is
surroundings, while disease is loss of ease (or comfort) to the going to happen (prognosis), what can be done about it
body (i.e. dis-ease). However, it must be borne in mind that in (treatment), and finally what should be done to avoid
health there is a wide range of ‘normality’ e.g. in height, weight, complications and spread (prevention) (i.e. ‘what’ of disease).
blood and tissue chemical composition etc. It also needs to be
appreciated that at cellular level, the cells display wide range EVOLUTION OF PATHOLOGY
of activities within the broad area of health similar to what is
seen in diseased cells. Thus, health and disease are not absolute Pathology as the scientific study of disease processes has
but are considered as relative states. its deep roots in medical history. Since the beginning of