Introduction to Pathology PDF

# Introduction to Pathology ## Introduction - The word PATHOLOGY is derived from two Greek words- 'Pathos' meaning suffering and 'logos' meaning study. - Pathology is a study of the structural, biochemical and functional changes in cells, tissues and organs that underlie disease. - It serves as a...

# Introduction to Pathology ## Introduction - The word PATHOLOGY is derived from two Greek words- 'Pathos' meaning suffering and 'logos' meaning study. - Pathology is a study of the structural, biochemical and functional changes in cells, tissues and organs that underlie disease. - It serves as a bridge between basic science and clinical practice. - It involves the investigation of the causes of disease and the associated changes at the levels of cells, tissues, and organs, which in turn give rise to the presenting signs and symptoms of the patient. - The range of the structural changes is from those affecting sub-cellular organelles (molecular pathology) up to alterations seen by the naked eye (gross pathology). ## Health And Disease - Health- complete physical, mental and social well being, not merely an absence of disease. - Disease- is expression of discomfort due to structural or functional abnormality. - Illness- means a condition marked by pronounced deviation from the normal healthy state. - Syndrome: (meaning running together) is used for a combination of several clinical features caused by altered physiologic processes. ## Terminology In Pathology - Patient- is a person affected by the disease. - Lesion- is characteristic changes in tissue and cells produced by disease. - Morphology- is examination of diseased tissue. - Etiology- is the cause of the disease (i.e. Why? Of disease) - Pathogenesis: Mechanism by which the lesions are produced (i.e. 'how' of disease). ## What should we know about a Disease? - Definition. - Epidemiology - Where & When. - Etiology - What is the cause? - Pathogenesis - Evolution of disease - Morphology - Structural Changes - Functional consequences - Management - Prognosis - Prevention ## Disease process > This is a diagram that can be described as a stack of 4 rectangles with arrows pointing to each one. The top rectanlge reads: _Clinical manifestations_. The second rectangle, just below and left of the first reads: _Pathogenesis_. The third rectangle, just below the second reads: _Molecular and morphological changes_. The bottom rectangle reads: _Etiology_. The arrows point from the bottom towards the top indicating that the etiology causes the pathogenesis, which causes the molecular and morphological changes, which cause the clinical manifestations. ## Etiology - Etiology of a disease means the cause of the disease. If the cause of a disease is known it is called primary etiology. - If the cause of the disease is unknown it is called idiopathic. - There are two major classes of etiologic factors: - Genetic and Acquired (infectious, nutritional, chemical, physical, etc). ## Pathogenesis - Pathogenesis means the mechanism through which the cause operates to produce the pathological and clinical manifestations or structural and functional abnormalities. - The incubation period, the time between exposure to the virus and the appearance of symptoms. - It is defined as the step by step developmental process from the beginning of the disease to its termination, or the mechanism by which the disease is developed. - The term pathogenicity refers to the ability of a pathogen (usually microbial pathogens) to cause disease. - The highly pathogenic influenza A virus subtype H5N1 which has caused serious disease outbreaks in poultry and human. - The nonpathogenic strains of Escherichia coli (E. coli) which live naturally in the large intestine of human and do not cause disease. ## Morphologic Changes. - The morphologic changes refer to the structural alterations in cells or tissues that occur following the pathogenetic mechanisms. - The structural changes in the organ can be seen with the naked eye or they may only be seen under the microscope. - GROSS MORPHOLOGIC CHANGES & MICROSCOPIC CHANGES. ## Clinical Manifestations. - The morphologic changes in the organ influence the normal function of the organ. - By doing so, they determine the clinical features (symptoms and signs), course, and prognosis of the disease. ## In summary, pathology studies:- > This is a diagram that can be described as a stack of 4 rectangles with a single arrow pointing to the right. The top rectanlge reads: _Etiology_. The second rectangle, just below and left of the first reads: _Pathogenesis_. The third rectangle, just below the second reads: _Morphologic changes_. The bottom rectangle reads: _Clinical features & Prognosis_. The arrow points from left to right indicating that the etiology causes the pathogenesis, which causes the morphological changes, which cause the clinical features & prognosis. ## Subdivisions of Pathology Pathology is broadly divided into two categories: 1. General pathology: Deals with general principle of disease e.g. inflammation, cancer, ageing. 2. Systemic pathology: Study of disease pertaining to the specific organs and body systems. >*In general the study of pathology includes morphological and non-morphological disciplines* ## THE TREE OF MEDICINE > This diagram represents a tree with branches and roots. At the very top sits the label _General Pathology_, its root system is comprised of the following items: _Anatomy_, _Embryology_, _Histology_, _Immunology_, _Pharmacology_, _Chemistry_, _Genetics_, _Microbiology_, _Physiology_, _Cell Biology_, _Physics_. The upper branches of the tree are comprised of the following: _Dermatology_, _Ophthalmology_, _Psychiatry_, _Anesthesiology_, _Neurology_, _Internal Medicine_, _Radiology_, _Dentistry_, _Gynecology_, _Pediatrics_, _Obstetrics_. > > This tree attempts to show the relationship between general pathology and other related fields within medicine. ## Symptom The term symptom refers to any evidence of a disease as told by the patient (in case of human being). ## Sign The term sign refers to any evidence of a disease detectable to a clinician (can be observed by the clinician). ## Diagnosis The term diagnosis refers to the art or act of identifying a particular disease from its signs and symptoms. ## Prognosis It is the prediction of the probable outcome of a disease. ## In summary: 1. Pathology is the study of what happened & how, the lesion is what & the sequence of events from the point of which the lesion began through its entire development (pathogenesis) is how. 2. It is necessary to know the pathogenesis of lesions in order to make a rational judgment for treatment, control & prevention of diseases. ## Objective and Purpose of pathological examination - Diagnosis of disease - Determining the treatment, prognosis, and grading. - Medico-legal conditions, to determine the cause of death - Researches and medical discovery