Pathology Lecture 5

Front 1

Apoptosis

Back 1

cell death based on sequential activation of“death genes”and suicide pathway enzymes . Also called“programmed cell death “
it is initiated by two important pathways :
1- Extrinsic pathway
2- Intrinsic mitochondrial pathway

Front 2

the Extrinsic pathway of apoptosis

Back 2

activated by death receptors on the surface of cellmembrane
Ligands for such receptors are proteins such astumor necrosis factor or Fas ligand .

Front 3

the Intrinsic pathway of apoptosis

Back 3

initiated byincreased mitochondrial permeability & the release of proapoptoticmolecules such as cytochrome C that acts oninitiator caspases that degrad the cell’sown nuclear DNA & nuclear & cytoplasmic proteins

Front 4

physiologic causes of apoptosis

Back 4

1.The programmed destruction of cells duringembryogenesis
2. Hormone deprivation
3. Cell loss in proliferating cell populations, as inintestinal crypt epithelia
4. Death of cells that have served their useful purpose

Front 5

Apoptosis in Pathologic Conditions

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(I) DNA damage
2. Accumulation of misfolded proteins
3. Cell injury in certain viral infections
4. Pathologic atrophy in parenchymal organs after ductobstruction ,

Front 6

Morphology of apoptosis:

Back 6

cells appear as: a rounded or oval masses, withintensely eosinophilic cytoplasm.
then ..
shrink , form cytoplasmic buds
&fragment into apoptotic bodies

Front 7

apoptotic bodies

Back 7

bodies composed of membrane-boundvesicles of cytosol & organelles of apoptotic cell

Front 8

Role of P53 gene in apoptosis

Back 8

P53 order damaged cell : To Stop → Repair Or Die!
when P53 is mutant or absent , is incapable of inducing apoptosis, so that cells with damagedDNA are allowed to survive. as in cancers .