Lect.no (5)
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  • Apoptosis come from the Greek word which means “falling off”.
  • 93
  • Shrinkage (pyknosis), increased nuclear staining (hyperchromasia), nuclear fragmentation (karyorrhexis, karryolysis), are classic features of apoptosis.
  • The two main cell which clean up dead cell fragments are macrophages (also called “histiocytes”) and neutrophils.
  • Caspases , or  c ysteine- asp artic prote ases , are a family of cysteine proteases, which play essential roles in apoptosis (programmed cell death), necrosis and inflammation. http://en.wikipedia.org/wiki/Caspases

Lect.no (5) Presentation Transcript

  • 1. Outcomes of necrosis:-1.Inflammation & resolution occurs if the injury is mild & the tissue has the power to proliferate.2.Inflammation & organization (fibrosis). occurs if the injury is severe &/or the tissuedo not have the power to proliferate.3. Dystrophic calcification- deposition of Ca++salts in necrotic tissue.
  • 2. Myocardial infarction (Posterolateral pale infarct) 2
  • 3. Inflammation& fibrosis of severe burn 3
  • 4. Aortic valve , gross , (calcified aortic stenosis). 4
  • 5. APOPTOSISApoptosis come from the Greek word which means “falling off”.
  • 6. Apoptosis• “A programmed active single cell death” that is induced by a tightly regulated intracellular program.Cells actually expend energy in order to die.• Causes of Apoptosis - Physiologic situations - Pathologic conditions
  • 7. APOPTOSIS• NORMAL (preprogrammed)• PATHOLOGIC (associated with Necrosis)
  • 8. Apoptosis in Physiologic Situations• Programmed destruction of cell during embryogenesis & development• Hormone-dependent tissue involution - endometrial cells (menstrual cycle)• Cell deletion in proliferating cell population e.g skin• Post-inflammatory clean up- neutrophils.• Cell death induced by cytotoxic T-cells to eliminate harmful cells - viral infected or tumor cells
  • 9. Apoptosis in Pathologic Conditions• Cell death produced by injurious stimuli – radiation, cytotoxic drug• Cell injury in certain viral diseases – viral hepatitis• Pathologic atrophy• Cell death in tumors .
  • 10. MORPHOLOGICAL FEATURES OF APOPTOSIS• Cell shrinkage• Chromatin condensation and fragmentation.• Formation of cytoplasmic blebs and apoptotic bodies.• Phagocytosis of apoptotic bodies by adjacent healthy cells or macrophages.• Lack of inflammation.
  • 11. Morphology of ApoptosisCell shrinkageChromosomecondensationFormation ofcytoplasmic blebsand apoptotic bodiesPhagocytosis ofapoptotic cells or cellbodies
  • 12. Cellular swelling, Membrane normalcell chromatin cluping damage The sequential ultrastructual changes in necrosis and apoptosisNuclear chromatin Cytoplasmic budding and Phagocytosisi ofcondensation and apoptosisi body apoptosis body fragmentation
  • 13. Apotosis of hepatocytes
  • 14. • Fig 1-18
  • 17. APOPTOSIS BIOCHEMISTRY• Protein Digestion (Caspases)• DNAbreakdown (endonucleases)• Phagocytic Recognition
  • 18. Comparison of cell death by apoptosis and necrosis
  • 19. Comparison of cell death by apoptosis and necrosis Feature Necrosis ApoptosisMechanism injurious programmed passive cell death active cell deathCell size Enlarged ReducedExtent single cell group of cellsNucleus Pyknosis / karyorrhexis / karyolysis condensation & Fragmentation (Apoptotic bodies)Plasma membrane Disrupted IntactCellular contents swell& Enzymatic digestion Intact
  • 20. Comparison of cell death by apoptosis and necrosisBiochemistry impairment & cessation of ion homeostasis Active DNA digestion lysosomes leak lytic enzymes by endonuclease lysosomes intactInflammation usual NoneFate of dead cells phagocytosed by inflammatory phagocytose by cells ( neutrophils & macrophages) macrophagesCause induced by pathologic stimuli induced by physiologic &pathologic stimuli