Cell Injury Flashcards
What is necrosis?
Death of most/all cells in an organ or tissue due to DISEASE, INJURY, or FAILURE of the BLOOD SUPPLY
What is reversible cell injury?
- Cells adapt to changes in environment
- Cells can return to normal once the stimulus is removed
What is irreversible cell injury?
- Permanent cell damage
- cell death as a consequence
What can determine if cell injury is reversible or irreversible?
- Depends on type, duration, severity of injury
- Susceptibility & adaptability of cell; nutritional status, metabolic needs
What are some causes of cell injury? (aetiology)
- Hypoxia (inadequate oxygen supply)
- Physical agents (radiation - free radicals)
- Chemicals/drugs
- Infections (bacterial toxins, viruses)
- Immunological reactions
- Genetic defects
- Nutritional imbalance
Is necrosis reversible or not?
Necrosis results in IRREVERSIBLE cell repair
What are the types of necrosis?
3 Types:
- Coagulative necrosis (cells aren’t broken down [no proteolysis] due to denaturation of enzymes)
- Liquefactive necrosis (digestion of dead tissue into a liquid viscous state)
- Caseous necrosis (Turns dead tissues into a cheese like appearance)
- Fibrinoid necrosis (special type of necrosis, seen in immune reactions in blood vessels)
What are the effects of necrosis?
- Functional (depends on organ/tissue)
- Inflammation
- Cell remains phagocytosed
- Necrotic area replaced by scar
What is apoptosis?
Genetically programmed cell death:
- eliminates unwanted cells
- does not cause inflammation
- important physiological role
What can trigger apoptosis?
- Hypoxia/ischaemia (results in protein misfolding)
- Infection (CD8+ T-cells can induce apoptosis)
- DNA damage (if unrepairable, p53 induces apoptosis)
Why is apoptosis important?
Maintains cell balance and health
Too much apoptosis = degenerative disease
Too little apoptosis = cancer
