Cell Death Mechanisms Quiz

Necrosis

• Liquefactive necrosis is characterized by bacterial infection and saponification.
• Pyroptosis is a type of programmed cell death characterized by the release of inflammatory mediators, such as IL-1, resulting in inflammation and fever.
• Ferroptosis is a type of programmed cell death characterized by peroxidation of lipids and is prevented by iron chelation.
• Coagulative necrosis is characterized by denaturation of proteins which blocks proteolysis, thus, preserving the architecture of dead tissues.

Apoptosis

• Activation of apoptotic pathways is a direct consequence of mitochondrial damage.
• Cell shrinkage is a characteristic of apoptosis.
• Apoptosis is a process of programmed cell death and can lead to accumulation of misfolded proteins, observed in embryogenesis, and apoptosis of cells that have served their purpose.
• Defective apoptosis leads to increased cell survival and increased cell death rate.

Inflammation & Thrombosis

• Gangrenous necrosis is characterized by ischemia followed by coagulative necrosis.
• Fibrinoid necrosis is characterized by deposition of antigen-antibody complexes and immune reactions.
• Hyperemia is an active process resulting in erythematous appearance of tissues.
• Thrombosis is a process of blood clot formation and is regulated by balance between anticoagulant and procoagulant activities of endothelium.
  • Antithrombotic properties of endothelium include:
    • Inhibition of platelet activation and aggregation by PGI2, NO, and ADP.
    • Inhibition of coagulation factor VIIa by thrombomodulin.
    • Activation of Protein C & S by thrombomodulin.
    • Direct inhibition of tissue factor VIIa and Xa by cell surface protein.
    • Activation of fibrinolysis to clear fibrin by t-PA
  • Procoagulant properties of endothelium include:
    • Release of von Willebrand factor (vWF) by endothelial cells.
    • Exposure of collagen by damaged endothelium.
• Hemorrhage is a blood leak and can present as petechiae, purpura, or ecchymosis.

### Other

• Pyknosis is characterized by condensation of chromatin into a solid, shrunken basophilic mass.
• Karyolysis is characterized by liquefaction of chromatin.
• Karyorrhexis is characterized by fragmentation of chromatin.
• Inability to reverse mitochondrial damage signifies the point of no return in cell injury.