Cell fate and injury Flashcards
What can cause cell injury and death?
- Injurious stimuli
- stress, increased demand —> adaptation —> inability to adapt -> cell injury —> death
What are the two types of cell injury?
Lethal: produces cell death
Sublethal: produces injury not amount to cell death may be reversible or progress to cell death
What are 8 potential causes of cell injury?
- oxygen deprivation
- chemical agents
- infectious agents
- immunological reactions
- genetic defects
- nutritional imbalances
- physical agents
- ageing
What does the cellular response to injurious stimuli depend on?
- Type of injury
- The duration of the injury
- Severity of the injury
What do the consequences of an injurious stimulus depend on?
- Cell type
2. Cell status
What are the 4 intracellular systems particularly vulnerable to injury? / what are the 4 mechanisms of cell injury?
- Cell membrane integrity
- ATP generation
- Protein synthesis
- Integrity of the genetic apparatus
Why do multiple secondary effects rapidly occur after cell injury?
When are morphological changes seen in the cell?
Multiple secondary effects rapidly occur as the structural and biochemical components of a cell are so integrally related
Cellular function is lost —> then cell death occurs —-> then morphological changes are seen
Cellular adaptions to injury:
What is atrophy?
What is hypertrophy?
Atrophy: shrinkage in the size of the cell (or organ) by the loss of cell substance.
Hypertrophy: increase in the size of cells and consequently an increase in the size of the organ
- can be physiological or pathological
- caused either by increased functional demand or specific hormonal stimulation
Cellular adaption to injury:
What is hyperplasia?
What is metaplasia?
What is dysplasia?
Hyperplasia: an increase in the number of cells in an organ.
- can be physiological or pathological
- physiological hyperplasia can either be hormonal or compensatory
- pathological hyperplasia is usually due to excessive hormonal or growth factor stimulation
Metaplasia: a reversible change in which one adult cell type is replaced by another
-may be physiological/pathological
Dysplasia: precancerous cells which show the genetic and cytological features of malignancy but not invading the underlying tissue
What are some light microscopic changes associated with reversible injury?
- fatty change
- cellular swelling
These = degenerative changes (associated w cell and tissue damage)
What is necrosis?
What are light microscopic changes associated with irreversible injury?
Necrosis = confluent cell death associated with inflammation
Light microscope changes associated with irreversible injury:
- coagulative necrosis - fried egg - MI
- liquefactive necrosis - waterfall - cerebral infarct
- caseous necrosis - cheese spilling out baguette - pulmonary TB
- fat necrosis - acute pancreatitis
What is apoptosis?
What are the main differences between apoptosis and necrosis?
Apoptosis = programmed cell death
In necrosis there’s enzymatic digestion and leakage of cellular contents
In apoptosis there’s phagocytosis of apoptotic cells and fragments
- Apoptosis may be physiological (whereas necrosis is always pathological)
- Apoptosis is an active energy dependent process (necrosis = passive)
- Apoptosis is not associated with inflammation
What are the 5 causes of apoptosis?
- Embryogenesis
- Deletion of auto-reactive T cells in the thymus
- Hormone dependent physiological involution
- Cell deletion in proliferating populations
- A variety of mild injurious stimuli that cause irreparable DNA damage that, in turn, triggers cell suicide pathways
What is necroptosis?
Necroptosis is programmed cell death associated with inflammation
There are many causes inc viral infections
