Introduction to Pathology and Cell Injury for Dental Students - Part 1 PDF

INTRODUCTION TO PATHOLOGY By Prof. Dr. Marwa Abd El Haq Professor of Pathology department Faculty of Medicine Tanta University  What is Pathology Pathology is study of disease Disease is a structural or functional a...

INTRODUCTION TO PATHOLOGY By Prof. Dr. Marwa Abd El Haq Professor of Pathology department Faculty of Medicine Tanta University  What is Pathology Pathology is study of disease Disease is a structural or functional abnormality in the tissues So, in other words, pathology is the study of structural and functional changes in the tissues due to disease “Patho” = disease “Logos” = to study Pathology is the scientific study of disease Structural Functional Cellular level Organ System Body 3  You need to have a basic knowledge of normal Anatomy (structure) and Physiology (function) to understand Pathology  Pathology deals with: Etiology: cause of the disease Pathogenesis: the sequence of cellular injury that led to disease. Morphologic changes of the disease: structural changes include both gross (seen by naked eyes) and microscopic changes of organs Clinical manifestations of a disease: signs and symptoms related to changes. Complications Prognosis Some pathology terms Diseases which present since birth are called Congenital diseases and diseases occur after birth are known as Acquired diseases Diseases which occur in families are known as Familial diseases Pathological features: gross and microscopic picture of the tissues Clinical features: signs and symptoms of the disease  General pathology includes 1. Cell injury 2. Adaptation to injury 3. Inflammation 4. Tissue repair 5. Hemodynamic disorders 6. Neoplasia Methods used in diagnosis Light microscope (hematoxylin & eosin, special stains) Immunohistochemistry Electron microscope Immunofluorescence CELL INJURY Overview of Cellular Responses to Stimuli Normal cell is in a steady state “Homeostasis” Homeostasis : equilibrium of the microenvironment of the cell – Chemical – electrolytes, glucose, pH,…etc. – Physical – temperature,….etc. When the cells are exposed to injurious agent, the effect of an injury on a tissue depends on: Duration of the Severity of the Type of cells injury injurious agent affected Cells Homeostasis Physiologic stress Pathologic stimuli Adaptation: adjusting to a new situation to preserve viability and function. Failure to adapt reversible Cell Injury irreversible  If the adaptive capability of the cell is exceeded or when cell is exposed to persistent damaging agents, cell injury occurs. Cell injury may be: – Reversible: return to normal after removal of the injury. or – Irreversible: Cell death or necrosis. Causes of Cell Injury 1. Hypoxia: oxygen deficiency (most common) - Ischemia: decreased blood supply - Inadequate oxygenation of blood as in pneumonia - Reduction in oxygen-carrying capacity of blood as in anemia, Co poisoning. 2. Infectious agents Viruses, bacteria, fungi, protozoa. 3. Chemical agents 4. Physical agents Trauma, extremes of temperature, radiation, electrical shock. 5. Immunologic reactions Ø Autoimmune reactions against one’s own tissues. Ø Allergic reactions. 6. Genetic defects Ø Can cause cell injury as inborn errors of metabolism. Ø Accumulation of damaged DNA 7. Nutritional imbalances Ø Protein insufficiency Ø Vitamin deficiencies Ø Excesses in nutrition – Obesity – diabetes mellitus, atherosclerosis. Reversible cell injury Disturbance in intracellular metabolism which is associated with swelling of the cell and accumulation of substances that are normally absent, invisible or present only in small amounts. Forms of reversible cell injury (degeneration) 1. Cloudy swelling/ hydropic degeneration 2. Fatty degeneration 3. Hyaline degeneration 4. Intra and extracellular accumulation of certain substances Reversible cell injury 1. Cloudy swelling/ Hydropic (ballooning) degeneration Ø Reversible cell injury characterized by cellular swelling Ø The most common type of degeneration Ø Due to mild accumulation of water Reversible cell injury Pathological features o Organs commonly affected: liver and convoluted tubules of the kidney o Gross picture: the affected organ become swollen, increased in size, heavy, pale in color, soft in consistency with rounded borders and tens capsule o Microscopic picture: Cells appear swollen Hydropic degeneration, kidney Chapter 5: Morphology of Ce 2. Fatty changes (Steatosis) Reversible cell injury characterized by intracellular accumulation of triglycerides within the cells Seen frequently in liver, and heart Fatty liver Gross picture of fatty changes The affected organ appears: Ø Enlarged in size Ø Heavy Ø Smooth outer surface& tense capsule Ø Soft in consistency & rounded borders Ø Cut section shows diffuse yellow color Normal cells à early Early changes à late fatty changes changes Reversible cell injury 3. Hyaline degeneration Ø It is deposition of homogenous pink protein material intra or extra- cellularly 1. Intra-cellular hyalinosis: Ø Russel bodies: hyaline degeneration of plasma cells in rhinoscleroma 2. Extracellular (CT) hyalinosis: Ø Hyaline degeneration in vessel wall as in hypertension, DM, and in old age in the rough endoplasmic reticulum of the plasma cells 3. Hyaline arteriolosclerosis in renal vessels in hypertension (Fig. 5.2). 5. Russell’s bodies representing excessive immunoglobulinsand2.diabetes Hyalinised old scar of fibrocollagenous tissues. mellitus. in the rough endoplasmic reticulum of the plasma cells4. 3.Hyalinised Hyaline arteriolosclerosis in renal glomeruli in chronic vessels in hypertension glomerulonephritis. EXTRACELLULAR HYALINE Extracellular hyaline (Fig. 5.2). and diabetes mellitus. commonly termed hyalinisation is seen in connective tissues. 5. Corpora amylacea seen as rounded masses of concentric A few examples commonly Intra and extra cellular hyalinosis EXTRACELLULAR of extracellularHYALINE termed hyalinisation is Extracellular hyaline change seen in are as under: connective 1. Hyaline degeneration in leiomyomas of the uterus brain tissues. 4. Hyalinised hyalinehyaline 5. laminae in Corpora glomeruli in chronic the enlarged amylacea glomerulonephritis. prostate in the elderly, in the and in the spinal cord in old age, and in of seen as rounded masses concentric old infarcts of A few examples of extracellular hyaline change are as under: thehyaline lung. laminae in the enlarged prostate in the elderly, in the (Fig. 5.3). brain and in the spinal cord in old age, and in old infarcts of 1. Hyaline degeneration in leiomyomas of the uterus (Fig. 5.3). the lung. Figure 5.2 !"Intracellular hyaline as Russell’s bodies in the plasma Figure 5.3 !"Extracellular hyaline deposit in leiomyoma uterus. The Reversible cell injury Intracellular accumulation Pigments: are colored substances not requiring stain to be seen Some of which are normal constituents of cells (e.g., melanin), others are abnormal and accumulate in cells only under special circumstances. Pigments may be exogenous (coming from outside the body) or endogenous (synthesized within the body)  Carbon Exogenous Lead pigments Tattooing Melanin Endogenous Hemoglobin-derived pigments pigments (bilirubin, hemosiderin) Endogenous pigments Nevus Melanoma Reversible cell injury Extracellular accumulation Pathological calcification Ø Abnormal deposition of Ca salts in tissues other than bone & teeth Ø Gross picture: white granules felt as gritty deposits Ø There are two types: 1. Dystrophic calcification 2. Metastatic calcification Dystrophic Metastatic calcification calcification Deposition of calcium salts in Deposition of dead or calcium salts ‫ه‬n degenerated normal tissues tissues Associated with normal serum Results from hypercalcemia levels of calcium