Harsh Mohan - Textbook of Pathology, 6th Edition

DEFINITION OF PATHOLOGY

The word ‘Pathology’ is derived from two Greek words—pathos meaning suffering, and logos meaning study. Pathology is, thus,scientific study of structure and function of the body in disease;
or in other words, pathology consists of the abnormalities that occur in normal anatomy (including histology) and physiology owing to disease. Another commonly used term with reference
to study of diseases is ‘pathophysiology’ comprised by two words:
patho=suffering;
physiology=study of normal function.
Pathophysiology, thus, includes study of disordered function or breakdown of homeostasis in diseases. Pathologists are the diagnosticians of disease. Therefore, knowledge and understanding of pathology is essential for all would-be doctors,general medical practitioners and specialists since unless they know the causes, mechanisms, nature and type of disease, and understand the language spoken by the pathologist in the form of laboratory reports, they would not be able to institute
appropriate treatment or suggest preventive measures to the patient. For the student of any system of medicine, the discipline of pathology forms a vital bridge between initial learning phase of preclinical sciences and the final phase of clinical subjects.
Remember the prophetic words of one of the eminent founders of modern medicine in late 19th and early 20th century, Sir William Osler, “Your practice of medicine will be as good as your understanding of pathology.”

HEALTH AND DISEASE

Before there were humans on earth, there was disease, albeit in early animals. Since pathology is the study of disease, then what is disease? In simple language, disease is opposite of health i.e.what is not healthy is disease. Health may be defined as a condition when the individual is in complete accord with the surroundings, while disease is loss of ease (or comfort) to the body (i.e. dis-ease). However, it must be borne in mind that in health there is a wide range of ‘normality’ e.g. in height, weight,
blood and tissue chemical composition etc. It also needs to be appreciated that at cellular level, the cells display wide range of activities within the broad area of health similar to what is seen in diseased cells. Thus, health and disease are not absolute but are considered as relative states.
A term commonly confused with disease is illness. While disease suggests an entity with a cause, illness is the reaction of the individual to disease in the form of symptoms (complaints of the patient) and physical signs (elicited by the clinician). Though disease and illness are not separable,
the study of diseases is done in pathology while the learning and management of illnesses is done in wards and clinics.In addition to disease and illness, there are syndromes (meaning running together) characterised by combination of symptoms caused by altered physiologic processes.https://drive.google.com/open?id=1ftcR5cOPifIRy1ZJjWxooMMbEEp43G9L