Cell Injury MNU Lecture Notes PDF

Cell Response to injury 1  Intended Learning Outcomes (ILOs) Enumerate causes and types of cell response to injury. Describe different mechanisms of cell injury. Compare between reversible and irreversible cell injury. Define different types of cell injury....

Cell Response to injury 1  Intended Learning Outcomes (ILOs) Enumerate causes and types of cell response to injury. Describe different mechanisms of cell injury. Compare between reversible and irreversible cell injury. Define different types of cell injury. Describe gross and microscopic pictures of different types of cell injury. Describe the pathogenesis and fate of types of reversible cell injury. Compare between necrosis and apoptosis. Compare between different types of necrosis. 2 Injury Cell 3 What is the causes of Cell Injury? 4  Physical Causes of Infection cell injury Chemical Hypoxia Immunological 5 6 Mechanisms of Cell Injury 7  1. ATP depletion 2. Membrane damage 3. Increases intracellular calcium 4. Formation of oxygen-derived free radicals 1 2 3 4 8 1 mainly caused by hypoxia 9 2 Another 3 effects10 3 11 3 Activation of multiple intracellular enzymes 12 4 as superoxide (O2-) and hydrogen peroxide (H2O2) 13  Effect of cell injury depends on Nature Duration Severity Type of cell 14 Reversible cell Irreversible cell injury injury Mild Severity Severe Short Duration Long Cell type Active parenchymatous cells with higher rate of metabolism suffer more than supporting stroma 15  Reversible cell Irreversible cell injury injury Types Cloudy swelling Necrosis Hydropic Apoptosis swelling Fatty change 16 Cloudy swelling Hydropic swelling Fatty Change 17 Definition Causes Pathogenesis Gross Microscopic Examples Fate 18 Reversible Cell Injury 19 Cloudy swelling Definition: Reversible cell injury characterized by swelling of the cells (due to water accumulation) and granularity of the cytoplasm. 20 Cloudy swelling Causes: 21 Cloudy swelling Pathogenesis: Accumulation of lactic acid & increase intracellular osmotic load 22 Cloudy swelling 23  Na Na Na K K K K 24 Cloudy swelling Gross & Microscopic: In Practical Section 25  Cloudy swelling Examples: Organs affected are highly specialized parenchymatous cells as Liver, kidney and heart. Clinically Dilatation & No significant decreased change Proteinuria contractility 26  Cloudy swelling Fate Injury stops Injury continues Cell returns to Proceeds to normal hydropic swelling 27 Reversible Cell Injury 28 Hydropic swelling Definition: Reversible cell injury characterized morphologically by swelling of the cells (due to excess water accumulation) and vacuoles in the cytoplasm. 29 Hydropic swelling Causes & Pathogenesis: As cloudy swelling 30 Hydropic swelling Gross & Microscopic: In Practical Section 31 Hydropic swelling Examples: 1) Liver cells: Ballooning degeneration in viral hepatitis and alcohol poisoning. 2) Epidermal cells: Burns, urticaria and viral infection as small box. 32 Hydropic swelling Fate Injury stops Injury continues Cell returns to Proceeds to normal Irreversible injury 33 Reversible Cell Injury 34 Fatty change Definition: Reversible cell injury characterized by pathological accumulation of excess fat in cells. 35  Fatty change Causes: 36  Fatty change Causes: Excess Viral Fat intake hepatitis 37  Fatty change Pathogenesis: Fat produced or carried to injured cells cannot be metabolized due to diminished enzyme activity, so it accumulates in cytoplasm 38  Fatty change Gross & Microscopic: In Practical Section 39  Fatty change Examples: Patchy Diffuse 40  Fatty change Patchy Examples: Chronic venous congestion (nutmeg liver) Diffuse Severe toxemia 41  Fatty change Patchy Examples: Prolonged moderate hypoxia, such as that produced by profound anemia (tigered effect) Diffuse Severe toxemia 42 Fatty change Fate Injury stops Injury continues Cell returns to Proceeds to normal Irreversible injury 43 Reversible Cell Injury 44 Irreversible Cell Injury 45  Necrosis Definition: Local death of a large groups of cells or tissues within the living body. It occurs either directly or 46 follows reversible injury  Necrosis Causes: 47  Necrosis Gross: surrounded by red area due to inflammatory hyperemia ???? 48  Necrosis Microscopic: Release of lysosomal enzymes 49  Necrosis Nucleus Microscopic: Pyknosis: Nuclear shrinkage with dense chromatin and increased basophilia. 50  Necrosis Nucleus Microscopic: Karyorrhexis: The pyknotic nucleus undergoes fragmentation (The nucleus breaks up to multiple small fragments) 51  Necrosis Nucleus Microscopic: Karyolysis: The nucleus dissolve and fail to take the stain due to chromatin hydrolysis. 52 Necrosis Nucleus 53  Necrosis Cytoplasm Microscopic: Cytomegaly (cells are swollen). Indistinct cell membrane. Ca2+deposition. 54  Necrosis Cytoplasm Microscopic: Cytoplasmic eosinophilia in H&E due to: 1. loss of cytoplasmic RNA 2. denatured cytoplasmic proteins 55  Necrosis Cytoplasm Microscopic: Glassy homogeneous appearance mainly as a result of the loss of glycogen particles. 56  Necrosis Examples = Types: Arterial Supply 57  Necrosis Examples = Types: 58  Necrosis Examples = Types: 59  Necrosis Examples = Types: 60  Necrosis Examples = Types: 61  Necrosis Types C C F F L Caseative Coagulative Fat Fibrinoid Liquefactive 62  Necrosis Fate Small area Large area solid debris engulfed by macrophages surrounded by fibrous capsule fluid drained by lymphatics dystrophic calcification healing (regeneration or fibrosis) 63  Necrosis Fate Small area Large area solid debris engulfed by macrophages surrounded by fibrous capsule fluid drained by lymphatics dystrophic calcification healing (regeneration or fibrosis) 64 Irreversible Cell Injury 65  Apoptosis 6 6  Apoptosis Definition: Death of single cell or small groups of cells. It is Energy-dependent programmed cell death to remove unwanted cells 67  Apoptosis Causes: Normal cell turnover Embryogenesis Physiologic Hormone dependent involution Death of cells finished their function DNA damage by RTH or CTH Cell death in infections (viral Pathologic hepatitis) Pathologic atrophy in parenchymal organs after duct obstruction 68  Apoptosis Gross:: Not observed by naked eye ???? 69  Apoptosis Microscopic:: Cell shrinkage. The cell is smaller in size; the cytoplasm is dense; and the organelles, though relatively normal, are more tightly packed. 70  Apoptosis Microscopic:: Formation of surface cytoplasmic blebs 71  Apoptosis Microscopic:: Membrane-bound apoptotic bodies composed of cytoplasm and tightly packed organelles, with or without nuclear fragments. 72 73  Apoptosis Fate:: Phagocytosis of apoptotic cells or cell bodies, usually by macrophages and degraded by the phagocyte's lysosomal enzymes. 74 Dr. Marwa Serag 75