Introduction to Pathology PDF

Introduction to pathology By Dr. Thaera H. Fruka Pathology is defined as: the study of disease by scientific methods. It is the study of changes which occur in cells and tissues as a result of any injury to the cell or tissue. Disease is defined as: an abnormality in structure or function of a...

Introduction to pathology By Dr. Thaera H. Fruka Pathology is defined as: the study of disease by scientific methods. It is the study of changes which occur in cells and tissues as a result of any injury to the cell or tissue. Disease is defined as: an abnormality in structure or function of any part of the body. (a physiological or psychological dysfunction.) There are 5 major aspects studied as part of pathology of any disease figure 1. Figure 1: clarifies the 5 major aspects studied as part of pathology of any disease 1- Epidemiology The term of epidemiology is a study of the occurrence and distribution of diseases in a population and the application of this knowledge to help the health system. It is the study of the patterns, causes, and effects of disease conditions in various populations. Epidemiology studies depend on factors: a. Sex b. Age c. Race d. Occupation: workers in asbestos industry can have diseases like asbestosis or tumors like mesotheliomas. workers in aniline dye industry can have urinary bladder cancer. hardwood workers can have nasal cancer from inhalation of wood dust etc. E. Geographic location: which part of the world a particular disease is common in, e.g: 1. underdeveloped countries has more malnutrition and infections like tuberculosis. 2. developed countries have more cardiac problems, obesity related diseases etc. Example on geographic location : a specific country suffers from water pollution , so a specific disease abounds there F- Socioeconomic strata: what is the social and financial status of the people affected by a particular disease. G- Prevalence: is the total number of cases of a particular disease in a particular population in a particular period of time. H- Incidence: is the number of new cases of a particular disease in a particularpopulation in a particular period of time (immunization programmes affect the incidence of a disease). i- Sequalea: is the complication or the consequence of a disease. J- Prognosis: is the expected outcome of the disease based on severity of any disease. ******prognosis: means prediction, patient’s prognosis could be one of the following: well prognosis: which means the patient is getting better. poor prognosis: which means the patient is getting worse which may lead to death. K- Morbidity: is the presence of illness. L- Mortality rate: is a measure of the number of people dead in a particular population during a particular period of time. Mortality rate can be calculated for any particular disease e.g. mortality rates are high for people with high grade cancers. i) sequalea: from the word sequence which in this concept means what happens to the patient after having the disease. What is the Purposes or importance of Epidemiology? 1. To investigate the extent of a disease in a community. 2. To study natural pattern/history and prognosis of disease. 3. To identify causes and risk factors. Ex.: Cause: chronic smoking. Risk: lung cancer 4. To provide good health care based on the findings. 5. To recommend and assist in various health programs e.g. immunizations and screening programs for different disease etc. 6.To evaluate all healthcare facilities and programs. 7.Provide information on public health in order to help the health care system and develop health policies. 2. Etiology & classification of disease Etiology in general pathology means the cause of the disease. If the cause of the disease is unknown it is called idiopathic/cryptogenic/ essential etc. Diseases are classified depending on the etiology and pathogenic mechanism involved. Disease can be congenital or acquired as mentioned in table1. 3. Pathogenesis Pathogenesis meaning a study of creation or beginning. Pathogenesis/Systematics Pathology: it is the steps that take place in the body once the problem begins (whatever it may be) that finally lead to tissue injury (pathological manifestations) There are four basic pathogenetic mechanisms take place in diseases: 1. Inflammatory process. 2. Degenerative process. 3. Carcinogenesis: transformation of normal cells to malignant. 4. Immunological process. Pathogenesis leads to morphologic changes in the gross or microscopic appearance of human tissue. 4. Morphologic changes Morphologic means architecture or structure of any part of the body. The morphologic changes are the structural changes that take place in cells or tissues due to any disease. These changes can be examined macroscopic and microscopic which helps the diagnosis of that disease figure 2. Figure 2: provides microscopic and macroscopic meaning 5.Clinical Features (Functional Alteration) When an organ is damaged by a disease, the normal function of that organ is affected and this will lead to the development certain clinical changes called signs & symptoms. Symptoms: is something experienced and reported by the patient e.g. ‘I am feeling tired’ , ‘I have a headache’, ‘I have a pain in my stomach’ etc. Basically it is what the patient will tell the doctor. Signs: are findings discovered by the physician during examination of the patient e.g. doctor finds a swelling somewhere or doctor find a liver or spleen enlargement while examining the abdomen etc. Basically it is what the doctor will find on examining the patient. The combination of signs and symptoms is called as clinical features