Introduction to Pathology PDF

Pathology - study (logos) of the disease(pathos) Etiology - causes, modifying factors, genetic predisposition, environmental factors Pathogenesis - steps of developing the disease Identification of gross morphological changes of cells and tissues, as wells as body fluids Introduction...

Pathology - study (logos) of the disease(pathos) Etiology - causes, modifying factors, genetic predisposition, environmental factors Pathogenesis - steps of developing the disease Identification of gross morphological changes of cells and tissues, as wells as body fluids Introduction to pathology Classification of the disease Classifications of diseases become extremely important in the compilation of statistics on causes of illness (morbidity) and causes of death (mortality) topographic- by bodily region or system anatomic- by organ or tissue physiological- by function or effect pathological - by the nature of the disease process etiologic (causal) epidemiological  topographic classification diseases are subdivided into such categories as gastrointestinal disease, vascular disease, abdominal disease, and chest disease Various specializations within medicine follow such topographic or systemic divisions, so that there are physicians who are essentially vascular surgeons  Anatomic classification disease is categorized by the specific organ or tissue affected; hence, heart disease, liver disease, and lung disease Medical specialties such as cardiology are restricted to diseases of a single organ, in this case the heart. Such a classification has its greatest use in identifying the various kinds of disease that affect a particular organ  physiological classification physiological classification of disease is based on the underlying functional derangement produced by a specific disorder Included in this classification are such designations as respiratory and metabolic disease. Respiratory diseases are those that interfere with the intake and expulsion of air and the exchange of oxygen for carbon dioxide in the lungs. Metabolic diseases are those in which disturbances of the body’s chemical processes are a basic feature. Diabetes and gout are examples.  pathological classification pathological classification of disease considers the nature of the disease process. Neoplastic and inflammatory disease are examples. Neoplastic disease includes the whole range of tumours, particularly cancers, and their effect on human beings.  etiologic classification etiologic classification of disease is based on the cause, when known. This classification is particularly important and useful in the consideration of biotic disease ( for examp: The disease is staphylococcal or rickettsial or fungal, what kinds of disease staphylococci produce in human beings It is well known that they cause skin infections and pneumonia, but it is also important to note how often they cause meningitis, abscesses in the liver, and kidney infections. The sexually transmitted diseases syphilis and gonorrhea are further examples of diseases classified by etiology.  Epidemiological classification epidemiological classification of disease deals with the incidence, distribution, and control of disorders in a population To use the example of typhoid, a disease spread through contaminated food and water, it first becomes important to establish that the disease observed is truly caused by Salmonella typhi, the typhoid organism. Once the diagnosis is established, it is obviously important to know the number of cases, whether the cases were scattered over the course of a year or occurred within a short period, and what the geographic distribution is It is critically important that the precise address and activities of the patients be established.  Cellular responses Cells - active participants in different processes, constantly changing their structure and function Normally maintain a homeostasis ( steady state) After encountering a physiologic or pathologic stress, they undergo adaptation  Cellular response stages 2 types of adaptation : physiologic and pathologic Hypertrophy Hyperplasia Atrophy Metaplasia  Hypertrophy Hypertrophy is an increase in the size of cells resulting in increase in the size of the organ. Physiological hypertrophy- estrogen stimulated smooth muscle hypertrophy in uterus during pregnancy Pathological hypertrophy - cardiac muscle enlargement Mechanism: mechanical trigger (stretch stimuli), trophic trigger (growth factors)  Hyperplasia Increase in cell number in response to stimuli Physiological hyperplasia - hormonal( proliferation of the glandular epithelium of the female breast at puberty), compensatory residual tissue growth after removal or loss of part of an organ( liver) Pathologic hyperplasia - excessive hormonal stimulation (disturbed balance between estrogen and progesterone causes endometrial hyperplasia, which is a common cause of abnormal menstrual bleeding hyperplastic process remains controlled, if the signals that initiate it abate, the hyperplasia disappears, in contrast to cancer , where growth control is dysregulated  Atrophy Shrinkage in the size of the cell by the loss of cell substance is known as atrophy. This kind of cells have diminished function , but they are not dead Causes: decreased mobility ( fracture) , loss of innervation(denervation atrophy), diminished blood supply(ischemia), inadequate nutrition(cachexia) , aging(senile atrophy) The mechanisms of atrophy consist of a combination of decreased protein synthesis and increased protein degradation in cells. Often followed by autophagy( self-eating) - process where cells eat its own components in an attempt to survive  Metaplasia a reversible change in which one adult cell type (epithelial or mesenchymal) is replaced by another adult cell type. Reprogramming of stem cells to differentiate along a new pathway rather than a phenotypic change (transdifferentiation) of already differentiated cells. Example of this is change of columnar cells into stratified squamous in smokers , with a disadvantage of the loss of protective mechanisms, such as mucus secretion and ciliary clearance Increase predisposition to lung cancer Barrett esophagus  Hypertrophy and hyperplasia Increase in size Increase in number Involves both dividing and non-dividing Occurs in cells able to undergo mitotic cells division Increased synthesis of proteins Increased proliferation due to increased Increase in cell size with nucleomegaly growth factors Reversible on withdrawal of stimulus Regress after stimuli stops, in contrast to neoplastic processes Thank you!