3-Necrosis and Apoptosis 2008 FINAL-part 1

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Transcript of 3-Necrosis and Apoptosis 2008 FINAL-part 1

  • ObjectivesDefine necrosis and apoptosisList the different types of necrosis, examples of each and its featuresList the different conditions associated with apoptosis, its morphology and its mechanismKnow the difference between apoptosis and necrosis

  • ObjectivesDefine necrosis and apoptosisList the different types of necrosis, examples of each and its featuresList the different conditions associated with apoptosis, its morphology and its mechanismKnow the difference between apoptosis and necrosis

  • Cell Death

    Death of cells occurs in two ways:

    Necrosis--(irreversible injury) changes produced by enzymatic digestion of dead cellular elements Apoptosis--vital process that helps eliminate unwanted cells--an internally programmed series of events effected by dedicated gene products

  • ObjectivesDefine necrosis and apoptosisList the different types of necrosis, examples of each and its featuresList the different conditions associated with apoptosis, its morphology and its mechanismKnow the difference between apoptosis and necrosis

  • Morphology of necrosis:

    Cellular swelling or ruptureDenaturation and coagulation of cytoplasmic proteinsBreakdown of cell organellesBreakdown of nuclear DNA

  • Patterns of Necrosis In Tissues or Organs As a result of cell death the tissues or organs display one of these six macroscopic changes:

    Coagulative necrosisLiquifactive necrosisCaseous necrosisFat necrosisGangrenous necrosisFibrinoid necrosis

  • Patterns of Necrosis In Tissues or Organs

    Coagulative necrosis: the outline of the dead cells are maintained and the tissue is somewhat firm. Example: myocardial infarction

    Liquefactive necrosis: the dead cells undergo disintegration and affected tissue is liquefied. Example: cerebral infarction.

  • Patterns of Necrosis In Tissues or Organs 3. Caseous necrosis: a form of coagulative necrosis (cheese-like). Example: tuberculosis lesions.

    4. Fat necrosis: enzymatic digestion of fat. Example: necrosis of fat by pancreatic enzymes. 5. Gangrenous necrosis: Necrosis (secondary to ischemia) usually with superimposed infection. Example: necrosis of distal limbs, usually foot and toes in diabetes.

    6. Fibrinoid necrosis: typically seen in vasculitis and glomerular autoimmune diseases

  • Coagulative NecrosisChanges in the cytoplasm and the nucleusKaryolysisPyknosisKaryorrhexis

  • Necrosis of the liver induced by herpesvirus. Herpesvirus invades liver cell nuclei producing nuclear ('ground glass') mildly basophilic inclusions.

  • Acute renal tubular necrosis (ischemia) :increased eosinophilia and pyknosis in necrotic cellsNormalNecrotic

  • Ischemic neuronal injury:acidophilic cytoplasm & nuclear pyknosis

  • a mess - so many cells have died - the tissue is not recognizable. Nuclei have become pyknotic (shrunken and dark), undergone karorrhexis (fragmentation) and karyolysis(dissolution)Necrotic myocardium

  • Kidney: ischemia and infarction (loss of blood supply and resultant tissue anoxia). Coagulative necrosisRemoval of the dead tissue leaves behind a scar

  • Infarcts (vascular distribution) are wedge-shaped with a base on the organ capsule. Coagulative necrosis: is due to loss of blood supply Spleen

  • Depending on circumstances: necrotic tissue may be walled off by scar tissue, totally converted to scar tissue, get destroyed (producing a cavity or cyst), get infected (producing an abscess or "wet gangrene"), or calcify.

    If the supporting tissue framework does not die, and the dead cells are of a type capable of regeneration, you may have complete healing.

    Remember: True coagulation necrosis involves groups of cells, and is almost always accompanied, by acute inflammation (infiltrate)