General Pathology 1st Semester 2024-2025 Northern Border University PDF

Northern Border University Faculty of Applied Medical Sciences Department of Medical Laboratory Technology General Pathology 1st Semester 2024 – 2025  Introduction to Pathology 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 2 ...

Northern Border University Faculty of Applied Medical Sciences Department of Medical Laboratory Technology General Pathology 1st Semester 2024 – 2025  Introduction to Pathology 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 2  Definition of Pathology 1. Literally translated, pathology is the study (logos) of disease (pathos, suffering). 2. The study of the essential nature of disease, disease processes, and the structural and functional changes in organs and tissues that cause or are caused by disease 3. The study of the gross and microscopic patterns of disease 4. More simply it is the medical science and specialty practice that deals with all aspects of disease “scientific study of disease”  Traditionally, the discipline is divided into: 1. General pathology 2. Systemic pathology  General pathology focuses on the cellular and tissue alterations caused by pathologic stimuli in most tissues.  While the systemic pathology examines the reactions and abnormalities of different specialized organs. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 3  Disease Disease define as external & internal problems that cause pain and/or interfere with a person's ability to work, play, and/or love others. Disease is an expression of "discomfort" due to structural or functional abnormality. Disease involves molecules, cells, tissues, organs, systems, whole persons, and groups of people. "Pathology deals with knowledge of what causes disease, how disease starts, progresses & it explains the reason for signs and symptoms of patient” Major groups of diseases are: - Inflammatory disorders are due to damage of tissues by various injuries (physical, chemical, infections etc.) - Degenerative disorders are due to lack of growth or ageing. - Neoplastic disorders are due to excess cell division forming tumours. - Progression of a disease:  Complete cure.  Death.  Complication.  Additional pathological changes which may occur during or after the course of any disease. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 4 The four aspects of a disease process that form the core of pathology are: 1. Etiology - Study of cause / causative agent of disease 2. Pathogenesis - (The mechanisms of its development) Study of disease progression or evolution (sequence and patterns of cellular injury that lead to disease) 3. Morphology - Study of the structural alterations induced in the cells and organs of the body (morphologic changes) 4. Clinical Significance - Study of the functional consequences of the morphologic changes and how clinical features are related to changes: a. Signs and symptoms b. Disease course c. Prognosis 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 5  1. Etiology Is the origin of a disease, including the underlying causes and modifying factors.  It is now clear that most common diseases, such as hypertension, diabetes, and cancer, are caused by a combination of inherited genetic susceptibility and various environmental triggers.  Understanding the genetic and environmental factors underlying diseases is a major theme of modern medicine. Factors causing disease could be :- – External factors (Environmental) … – Internal factors (Genetic) … Diseases which present since birth are called Congenital diseases and all other diseases are known as Acquired diseases. Diseases which occur in families are known as Familial diseases. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 6  1. Etiology A) Environmental factors: 1. Hypoxia: decrease oxygen supply (most common) 2. Physical (heat, cold, radiation or electric shock) 3. Chemical (acids, alkalies, poisons, some drugs) Pollution 4. Infection (bacteria, viruses, fungi, parasites) and probably prions 5. Mechanical (trauma) 6. Nutritional or vitamin imbalance 7. Immunological reactions B) Genetic factors: 1. Congenital 2. Hereditary: enzyme 3. Mutations C) Multifactorial factors: 1. Diabetes 2. Hypertension 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 7  2. Pathogenesis  Pathogenesis refers to the steps in the development of disease.  Is define as the mechanisms by which the causative agent causes the disease.  “Sequence of events in the response of cells & tissues to a stimulus/pathogen” starting from the initial stimulus to the ultimate expression of disease.”  It describes how etiologic factors trigger cellular and molecular changes that give rise to the specific functional and structural abnormalities that characterize the disease.  Whereas etiology refers to why a disease arises, pathogenesis describes how a disease develops.  Many times the pathogenesis or etiology is unknown, in which case we say that the disease pathogenesis is idiopathic.  The pathogenesis process leads to the formation of lesion.  Lesion is derived from the Latin word "laesio" which means "injury."  Lesions are a result of damage to tissues. For example:  A cancerous tumor is an example of a lesion.  The surrounding tissue damaged by a tumor is also termed a lesion. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 8  3. Morphology The relationships among normal, adapted, and reversibly and irreversibly injured cells are well illustrated by the responses of the heart to different types of stress  Structural changes in cells, tissues and organs that are characteristic of the disease or condition.  Gross (macroscopic picture)  changes detected on naked eye examination  Microscopic (LM/EM)  changes detected on microscopic examination. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 9  4. Clinical significance Functional de-arangements and its clinical manifestations resulting from the morphologic changes. Signs and symptoms, course and prognosis of disease depend on the morphology. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 10  Overview of cellular responses to stress and noxious stimuli Cells are active participants in their environment, constantly adjusting their structure and function to accommodate changing demands and extracellular stresses. Cells normally maintain a steady state called homeostasis in which the intracellular milieu is kept within a fairly narrow range of physiologic parameters. As cells encounter physiologic stresses or pathologic stimuli, they can undergo adaptation, achieving a new steady state and preserving viability and function. The principal adaptive responses are hypertrophy, hyperplasia, atrophy, and metaplasia. If the adaptive capability is exceeded or if the external stress is inherently harmful, cell injury develops. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 11  Stages in the cellular response to stress and injurious stimuli. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 12 Cellular Adaptations of Growth and Differentiation  Cells respond to increased demand and external stimulation by hyperplasia or hypertrophy, and they respond to reduced supply of nutrients and growth factors by atrophy.  In some situations, cells change from one type to another, a process called metaplasia.  Cellular adaptations to stress:  Adaptations are reversible changes in the number, size, phenotype, metabolic activity, or functions of cells in response to changes in their environment.  Physiologic adaptations usually represent responses of cells to normal stimulation by hormones or endogenous chemical mediators  (e.g., the hormone-induced enlargement of the breast and uterus during pregnancy).  Pathologic adaptations are responses to stress that allow cells to modulate their structure and function and thus escape injury. Such adaptations can take several distinct forms. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 13  Hypertrophy  Is an increase in the size of cells resulting in increase in the size of the organ, often in response to increased workload; induced by growth factors produced in response to mechanical stress or other stimuli; occurs in tissues incapable of cell division  Hypertrophy can be physiologic or pathologic and is caused either by increased functional demand or by growth factor or hormonal stimulation.  The massive physiologic enlargement of the uterus during pregnancy occurs as a consequence of estrogen stimulated smooth muscle hypertrophy and smooth muscle hyperplasia.  An example of pathologic cellular hypertrophy is the cardiac enlargement that occurs with hypertension or aortic valve disease. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 14  Left ventricle Hypertrophy 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 15  Hyperplasia  Is an increase in the number of cells in an organ or tissue  Hyperplasia can be physiologic or pathologic. The two types of physiologic hyperplasia are: (1) Hormonal hyperplasia:  Best exemplified by the proliferation of the glandular epithelium of the female breast at puberty and during pregnancy and the physiologic hyperplasia that occurs in the pregnant uterus. (2) Compensatory hyperplasia:  In which residual tissue grows after removal or loss of part of an organ. For example, when part of a liver is resected, mitotic activity in the remaining cells begins as early as 12 hours later, eventually restoring the liver to its normal weight.  Pathologic hyperplasia: Most forms of pathologic hyperplasia are caused by excessive hormonal or growth factor stimulation. For example, after a normal menstrual period there is a burst of uterine epithelial proliferation that is normally tightly regulated by stimulation through pituitary hormones and ovarian estrogen and by inhibition through progesterone. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 16  Hyperplasia Hyperplasia also is an important response of connective tissue cells in wound healing, in which proliferating fibroblasts and blood vessels aid in repair. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 17  Hyperplasia 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 18  Atrophy  Shrinkage in the size of the cell by the loss of cell substance is known as atrophy. When a sufficient number of cells are involved, the entire tissue or organ diminishes in size, becoming atrophic.  Although atrophic cells may have diminished function, they are not dead. The common causes of atrophy are the following:  1. Decreased workload (atrophy of disuse).  2. Loss of innervation (denervation atrophy).  3. Diminished blood supply.  4. Inadequate nutrition.  5. Loss of endocrine stimulation.  6. Aging (senile atrophy).  7. Pressure. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 19  Atrophy 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 20  Atrophy Atrophy as seen in the brain. A, Normal brain of a young adult. B, Atrophy of the brain in an 82-year-old man with atherosclerotic disease. Atrophy of the brain is due to aging and reduced blood supply. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 21  Metaplasia  Reversible change in which one adult cell type (epithelial or mesenchymal) is replaced by another adult cell type  In this type of cellular adaptation, a cell type sensitive to a particular stress is replaced by another cell type better able to withstand the adverse environment.  Epithelial metaplasia is exemplified by the squamous change that occurs in the respiratory epithelium of habitual cigarette smokers. 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 22  Metaplasia 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 23  Pathological investigation  During life:  Surgical biopsy.  Fine needle aspiration biopsy (FNAB).  Cytopathology.  Molecular techniques.  After death:  Autopsy. Objectives of Pathology: 1- Diagnosis and treatment 2- Asses the extent of the disease 3- Prognosis 4- Progress 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 24 Methods use to achieve the objectives of Pathology 1. Gross examination of organs (Macroscopic): (a) Gross examination of organs on the exam (b) Useful gross features 2. Microscopic examination of tissue: Light microscopy: a. Routine stain: b. Histochemical stains (chemical reactions) c. Immunohistochemical (antibody) stains 3. Ancillary techniques a. Immunofluorescence microscopy (IFM) b. Transmission electron microscopy (EM) 4. Molecular techniques: a. In situ hybridization b. Filter Hybridization c. Polymerase chain reaction (PCR) 5. Flow Cytometry 6. Cytogenetic 7. TUNNEL assay 8. Other methods for cell proliferation analysis 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 25.. THANK YOU THANK YOU 8/17/2024 NBU, AMS, Dr.EIM & DMO, Histo 26