Cell Injury And Death Flashcards
What are two outcomes of a stimulus being applied to a cell?
Adaptation Cell injury (if injurious stimulant or unable to adapt)
If a cell injury is irreversible what are the two outcomes?
Necrosis and apoptosis
How might a cell adapt?
Increased cellular activity (hyperplasia, hypertrophy)
Decreased cellular activity (atrophy)
Metaplasia
What are the causes of cell injury? (5)
- Oxygen availability
- Physical trauma
- Microbial
- Immunological
- Chemical
Also developmental/genetic disorders, nutritional, ageing
What is often a cause of cell injury caused by oxygen availability?
Ischaemia
What is a secondary harmful effect of lack of oxygen?
Reperfusion, phagocytes response to injured tissue, inflammatory response, reactive O2 and nitrogen species produced
What can be the effect of physical trauma, other than the obvious?
Body can respond with reactive oxygen species
5 things that cause microbial damage
Viral Bacterial exotoxins Yeast Fungi Intercellular parasites
2 ways immunological damage can happen
Antigen-antibody complex deposition
Cells are not recognised as self and are attacked
How could physiologically present ‘chemicals’ cause damage?
If present in wrong concentration
6 mechanisms of cell injury
Lack of ATP Mitochondrial damage Altered intracelluar Ca2+ levels ROS Membrane damage Protein denaturation
What is a sublethal cell injury?
Cell swelling and fatty changes
How does lack of ATP injure the cell?
Ion gradients can’t be maintained
Other than contributing to ATP depletion, how does mitochondrial injury cause cell injury?
Triggers caspase-mediated apoptotic cascades that = death of cell
Clumping of nuclear chromatin
Cellular swelling due to ion concentration changes
Lipid deposition due to protein synthesis reduction
How does altered intracellular calcium levels damage the cell?
- Mitochondrial membranes more permeable.
- Dysregulation of many calcium dependent processes.
- Increased calcium activates enzymes- ATPases, phospholipases, proteases etc could all damage cells.
What are reactive O2 species?
Species with unpaired electrons or more stable but still reactive compounds such as hydrogen peroxide.
Which species detoxify free radicals?
Superoxide dismutase
Antioxidants
Is necrosis active or passive?
Passive
Why does necrosis occur?
Lethal cell injury
What process does necrosis incite?
Inflammation
What are 6 types of necrosis? Which is most common?
Coagulative (most common) Caseous Colliquative Gangrenous (wet and dry) Fat Fibrinoid
Describe coagulative necrosis
Denaturation of intracytoplasmic protein. Dead tissue firm and swollen, retains microscopic architecture. Typical of ischaemic injury (except brain). Cellular proteins may leak into blood (e.g. MI diagnosis)
Describe caseous necrosis
Characteristic of TB. Cheese like, cellular detail destroyed and surrounded by granulomatous infection. Dead tissue lacks structure
Describe colliquative necrosis
Due to some infections or in the CNS LACK OF INFECTION. Liquefaction and cyst formation
