More Related Content
What's hot
What's hot (20)
Similar to Cell death
Similar to Cell death (20)
Recently uploaded
Recently uploaded (20)
Cell death
- 1. Cell death
- 2. Cellular adaption • Atrophy- decrease in cell size • Hypertrophy- increase in cell size • Hyperplasia- increase in number of cells • Metaplasia- one cell form to another • Dysplasia- change is cellular shape https://www.slideshare.net/DeepakKuma rGupta2/cellular-adaptation-53513522
- 4. Example of apoptosis in embryo https://www.khanacademy.org/science/biology/developmental-biology/apoptosis-in-development/a/apoptosis
- 5. Human embryo hand development inutero
- 7. Apoptosis programmed cell death • Apoptosis means- dropping off • Reference to dropping off cell that are no longer useful • Part of normal development – Apoptosis prunes the embryonic ducts during gender specific development • Tissue turnover • Role in the immune system • Undesirable cells
- 8. Role of apoptosis Key roles in- • Growth • Immune surveillance • Neoplastic development https://slideplayer.com/slide/4446840/
- 12. Intrinsic apoptosis • Bcl-2 controlled pathway • Activation of caspases from inside the cell • Formation of an intracellular caspase-9-activating complex (apoptosome) • Apoptosome forms after cytochrome c is released from the mitochondria
- 13. Apoptosome
- 14. Bcl-2 family • Consists of a hydrophobic α-helix surrounded by amphipathic α-helices • Some members of the family have transmembrane domains at their c-terminus • Bcl2 stops channel formation on the surface of mitochondria so cytochrome c not released through the channel
- 16. Caspase • Cysteine protease • The intrinsic apoptotic pathway is characterized by permeabilisation of the mitochondria and release of cytochrome c into the cytoplasm. • Cytochrome c then forms a multi-protein complex known as the "apoptosome" and initiates activation of the caspase cascade through caspase 9
- 18. Overview of the apoptotic pathway https://oncohemakey.com/the-scientific-basis-of-cancer/
- 19. Morphological features of apoptosis in comparison • Chromatin aggregation - nuclear and cytoplasmic condensation to form apoptotic bodies • Organelles remain intact • Intact membrane surrounds apoptotic bodies • No inflammatory response • Apoptotic bodies phagocytosed by adjacent cells and macrophages • Typically affects isolated cells • Surrounding cells remain in tact
- 20. https://www.youtube.com/watch?v=- vmtK-bAC5E Neurodegeneration from apoptosis • Huntingdon's disease • Alzheimer's • Parkinson’s https://www.dreamstime.com/stock-illustration-apoptosis-neuron-which-observed-different-diseases-such-as-viral-encephalitits-neurodegenerative-psychiatric-image79864414
- 22. Genetic defects in apoptosis • Mutations rare but- • Common mutation in Fas gene • Mutation in FasL gene • Caspase-1 mutation occurs rarely (NALP3 gene) Autoimmune lymphoproliferative disorder (ALPD)
- 23. Necrosis un-programmed cell death Necrosis means making dead Accidental death of cells through- • Injury • Infection • Cancer • Infarction • Toxins • Inflammation • No regulated signals to phagocytes to ‘clear’ necrotic cells and avoid immune surveillance https://www.youtube.com/watch?v=vAYB6QWuOdM
- 25. Mechanism of necrosis • Unable to pump out Na+ • Cell swells though osmosis • Insult of necrosis injures many surrounding cells • Intracellular products initiate an inflammatory response • This can harm surrounding healthy tissues
- 26. Detailed events of necrosis • Cell shrinkage and rounding occur because of the retraction lamellipodia and the breakdown of the proteinaceous cytoskeleton by caspases. • Mitochondria become ‘leaky’ • The cytoplasm appears dense, and the organelles appear tightly packed. • Chromatin undergoes condensation into compact patches against the nuclear envelope (also known as the perinuclear envelope) in a process known as pyknosis, a hallmark of apoptosis. • The nuclear envelope becomes discontinuous and the DNA inside it is fragmented in a process referred to as karyorrhexis. The nucleus breaks into several discrete chromatin bodies ornucleosomal units due to the degradation of DNA
- 27. Cell shrinkage and rounding occur because of the retraction lamellipodia and the breakdown of the proteinaceous cytoskeleton by caspases.
- 31. Morphological features of Necrosis Cell membrane integrity lost and lysosomal hydrolases released, resulting in - • Nuclei small, condensed • Pyknosis- nuclei stain deeply with hematoxylin (basophilic) • Karyorrhexis- nuclei fragmented into particles • Karyolysis- nuclear lysis • Cytoplasm deeply eosinophilic (RNA loss, protein coagulation) • Typically affects large groups of cells
- 33. Morphological patterns of Necrosis • Coagulative necrosis, typically in hypoxic cells with few lysosomes • MI • Infarct of spleen • Liquifactive necrosis in cells with numerous lysosomes or where bacteria attract neutrophils • Pneumonia • Brain hypoxia • Gummatous necrosis restricted to spirochaetal infections • Syphylis • Haemorrhagic necrosis - blockage of venous drainage of tissue or organ • eg. Testicular torsion
- 34. Types of necrosis Coagulative necrosis Liquefactive necrosis Digestive release of lysosomal enzymes turn tissue into pus (CNS) Can also occur in lungs with abscesses Typically occurs with infarcts or ischemia Architecture of dead tissue preserved `regeneration can occur with enough viable cells
- 35. Types of necrosis Fat necrosis Fibrinoid necrosis Seen in autoimmune diseases, vasculitisChalky white deposites
- 36. Examples of different types of necrosis Caseous necrosis Cheese like, yellow-white area Combines features of Coagulative and liquefative. Found in centre of tuberculous infections Gumatous necrosis Rubbery texture of tissue of the hard pallet
- 37. Diseases associated with necrosis • Autoimmune vasculitis • Peripheral vascular disease • Osteonecrosis of the jaw • Aseptic bone necrosis • Gangrene • Ishaemic cascade (stroke) • Necrotoxins cause necrosis • Cystic medial necrosis • Tumour necrosis due to hypoxia-angiogenesis Gangrenous necrosis
- 38. Irreversible versus reversible necrosis Irreversible • Cell digestion by lytic enzymes • Protein denaturation • Hypoxia, chemical and physical agents, microbial, immunological injury Reversible
- 43. Cell Death Necrosis • Pathological cell death - external factors • Hypoxia, chemical toxins cause necrosis • Damage to cell physiology • Degradation of the cell • Influx of water and ions • Cellular organelles swell and rupture Apoptosis • Programmed or physiological cell death • Constituent genes cause cell death
- 46. Morphological patterns of Necrosis • Coagulative necrosis, typically in hypoxic cells with few lysosomes • MI • Infarct of spleen • Liquifactive necrosis in cells with numerous lysosomes or where bacteria attract neutrophils • Pneumonia • Brain hypoxia • Gummatous necrosis restricted to spirochaetal infections • Syphylis • Haemorrhagic necrosis - blockage of venous drainage of tissue or organ • eg. Testicular torsion
- 47. Diseases associated with necrosis • Autoimmune vasculitis • Peripheral vascular disease • Osteonecrosis of the jaw • Aseptic bone necrosis • Gangrene • Ishaemic cascade (stroke) • Necrotoxins cause necrosis • Cystic medial necrosis • Tumour necrosis due to hypoxia-angiogenesis
- 48. Etiological Importance of Apoptosis • Suppressed apoptosis – Neoplasia – Autoimmunity • Abnormally induced – AIDS – Neurodegenerative disease