W2 Cell Injury, Cell Adapation & Cell Death PDF

CELLULAR ADAPTATION Presented by: Dr.Marwah Albakri  Outlines o Causes of cell injury o Cell injury o Irreversible cell injury o Necrosis o Apoptosis o Cell adaptation o Hyperplasia o Hypertrophy o Atrophy o Dysplasia  Causes of Cell Injury * All causes of cell injury can...

CELLULAR ADAPTATION Presented by: Dr.Marwah Albakri  Outlines o Causes of cell injury o Cell injury o Irreversible cell injury o Necrosis o Apoptosis o Cell adaptation o Hyperplasia o Hypertrophy o Atrophy o Dysplasia  Causes of Cell Injury * All causes of cell injury can be divided into : Hereditary causes Acquired causes ▪ Hypoxia: shortage of oxygen ▪ Physical agents: trauma, burns, deep cold, radiation … ▪ Chemicals: conc. O2, NO, alcohol, smoking … ▪ Infectious agents; bacteria, viruses … ▪ Immunologic reactions; eczema, SLE … ▪ Genetic mutations * Morphogenesis of cell and intercellular matrix injury: 1.infiltration - redundant accumulation of metabolites into the cells and intercellular matrix. 2.Decomposition (phanerosis) - disintegration of membranous structures of the cells and intercellular matrix. 3.Perverted synthesis - synthesis of abnormal substances in the cells and tissues, that are not meeting in a norm. 4.Transformation - formation of one type of metabolism's products from common initial substances for proteins, fats and carbohydrates. Poll Question No. 1 What do you think injured cells do? A. Must Die B. Get hurt C. Try to survive D. All of the above E. None of the above  Cell Injury ▪ Cells encounter physiologic stress or pathologic stimuli = undergo adaptation (homeostasis) ▪ Cells achieve a new steady state to preserve viability and function Reversible ▪ Ultimate fate of a cell depends on type, severity and duration of stimulus and also the type of cell Irreversible  Cell Injury * Cell injury can be: Reversible injury is characterized by the ability of the cell to return to its normal stat. (Hyperplasia, Hypertrophy, Atrophy, Metaplasia) 1.Irreversible cell injury leads to cell death Necrosis or apoptosis  Irreversible Cell Injury ▪ Irreversible cell injury occurs if the stimulus was sever enough or persists ▪ Cell death is the ultimate result of cell injury: Necrosis, Apoptosis, Pyroptosis, Autophagy..etc. ▪ Cell death has two forms: o Necrosis pathologic elicit inflammation o Apoptosis physiologic no elicit inflammation Irreversible Cell Injury  Necrosis ▪ Is the local death of cells or tissues within the living body ▪ Necrosis stages: Normal pyknosis karyohexis karyolysis  Apoptosis ▪ Apoptosis: a programmed cell death ▪ Controlled cell death to eliminate unwanted cell ▪ Apoptosis: cytoplasmic blebs apoptotic bodies phagocytosis Poll Question No. 2 Which type of cell death marked by the blue arrow? A. apoptosis B. Necrosis  Necrosis ▪ Necrosis has various forms including; coagulative, Liquefactive, caseous, and fat necrosis ▪ Effects of necrosis include: Dysfunction, release of cell enzymes, systemic-fever, bacterial infections --- gangrene Necrosis: a) Caseation Necrosis: Less structure, granular or homogenous & pink (H&E) e.g. TB b) Liquifactive Necrosis: neutrophils (CNS) c) Coagulative Necrosis: ghost appearance cells d) Fat necrosis: shadowy fat cells outlines  Apoptosis ▪ Apoptosis might indicate DNA damage ▪ Apoptosis failure might lead to cancer Apoptosis vs Necrosis Poll Question No. 3 The main difference between apoptosis & necrosis is that apoptosis occurs in an organized fashion and necrosis occurs without a nuclear signal/order. A. Yes B. No Ji, Nan, et al. "Pyroptosis: a new regulating mechanism in cardiovascular disease." Journal of inflammation research 14 (2021)  Cellular Adaptation Hyperplasia Hypertrophy Atrophy Metaplasia  Hyperplasia Increase in cell number in specific tissue or organ leading to tissue or organ enlargement Hyperplasia might be due to physiologic or pathologic causative Physiologic hyperplasia: ▪ Hormonal hyperplasia: Endometrium & breast ▪ Compensatory hyperplasia: Liver, BM & a single lung, kidney …  Hyperplasia Pathologic hyperplasia: ▪ Hormonal hyperplasia; prostate, thyroid gland ▪ Viral infections; HPV  Hyperplasia Pathologic hyperplasia: ▪ Hormonal hyperplasia; prostate, thyroid gland ▪ Viral infections; HPV  Hyperplasia Pathologic hyperplasia: ▪ Hormonal hyperplasia; prostate, thyroid gland ▪ Viral infections; HPV  Hypertrophy Increase in the cell size leading to enlargement of the tissue or organ Hypertrophy may be due to physiologic or pathologic reasons Physiologic hypertrophy: ▪ Hypertrophy in skeletal muscle (exercise) ▪ Hypertrophy of myometrium (pregnancy) Poll Question No. 4 This lady has thyroid problem due to less iodine intake, which hypertrophy type you guess? A. Physiologic B. Pathologic  Hypertrophy Pathologic hypertrophy: ▪ Hypertrophy of the left ventricle in response to severe aortic stenosis  Atrophy ▪ A form of cell adaptation in response to decreased trophic influences, decreased functional demands or decreased nutrition. ▪ Causes of atrophy may include: ✓ Physiologic atrophy ✓ Lack of nutrients ✓ Diminished blood supply ✓ Interruption of specific trophic ✓ Disuse atrophy ✓ Pressure atrophy ✓ Aging  Atrophy Atrophy: decrease in organ size ▪ Brain atrophy; In late adult life, the brain undergoes progressive atrophy. Atherosclerosis? Alzheimer disease?  Atrophy Muscle atrophy? Neurogenic atrophy?  Metaplasia ▪ Metaplasia is defined as the replacement of one type of cells with another type, often as an adaptation process ▪ Metaplasia – dysplasia – cancer (oesophageal) ▪ 2% might develop cancer Metaplasia Home work: Which is which? Original cells The end …