Cell Ageing and Death Flashcards
What is atrophy?
Reduction in size of cell.
What are the two types of Cell Death?
- Necrosis.
2. Apoptosis.
Define necrosis.
Form of cell death that requires NO ENERGY.
Always pathological, never physiological.
What are the types of necrosis?
- Coagulative
- Liquefactive
- Caseous
What happens in coagulative necrosis?
Dead cells consumed by various enzymatic processes. Cell outline is preserved around the dead cells.
Common in MI.
What happens in liquefactive necrosis
Liquid viscous mass- no cell structure remains.
Pus formation. Associated with localised bacterial/fungal infections.
Common in necrosis in the brain.
What happens in caseous necrosis?
Granulomatous inflammation with central necrosis.
Almost always associated with TB.
To confim TB:
Blood culture, PCR, Ziehl Neelson stain.
Define apoptosis.
Programmed cell death in response to signals. Requires energy.
What is physiological apoptosis. Give an example.
When some cells die off naturally in the body as needed.
Eg self reacting lymphocytes.
Hormone dependent involution.
What is pathological apoptosis? when does it occur?
Apoptosis occurring in response to injury.
Examples:
Chemo, radiation, viral infection, cancers, graft vs host disease.
What is the extrinsic pathway of apoptosis?
Death receptor initiated pathway.
Cell membrane receptors with death domain.
Death receptors: TNF, Fas
What happens in fas?
fas- self recognition
eg apoptosis in lymphocytes.
people with fas mutations often have autoimmune conditions.
TNF- Induces apoptosis in inflammatory conditions.
What is the intrinsic pathway of apoptosis?
Mitochondrial pathway: Growth signals promote anti apoptotic molecules. These molecules removed by BAK, BAX. Increased mitochondrial permeability. Stimulation of caspases Eg cytochrome C
What is the role of p53?
Detect damage in DNA during cell cycle.
Stops cell cycle, only resumed once damage is repaired.
If unable to repair–> p53 stimulates apoptosis.
What are some causes of cellular ageing?
Oxidative stress-free radical damage
Accumulation of metabolic by-products- lipofuscin
