Cell fate and injury (7) Flashcards
What is the difference between lethal and sublethal cell injury?
lethal: produces cell death
sublethal: produces injury not amounting to cell death- may be reversible, or progress to cell death
What are causes of cell injury?
- oxygen deprivation
- chemical agents
- infectious agents
- immunological reactions e.g. autoimmunity
- genetic defects
- nutritional imbalances
- physical agents e.g. radiation, gun wound
- ageing
What does ischaemia lead to?
ischaemia= oxygen deprivation
leads to infarction= death of tissue
What 4 intracellular systems are particularly vulnerable to injury?
- cell membrane integrity–> immediate injury
- ATP generation
- protein synthesis–> slower injury
- integrity of genetic material
What is atrophy?
shrinkage in the size of a cell/organ by the loss of cell substance
What is hypertrophy?
- increase in the size of cells and therefore organ
- can be physiological or pathological
- caused by increased functional demand e.g. athletes or specific hormonal stimulation e.g. pregnancy
What is hyperplasia?
- increase in the number of cells in an organ
- can be physiological (hormonal or compensatory e.g. if kidney removed) or pathological (excessive hormonal e.g. excess TSH or growth factor stimulation)
What is metaplasia?
- REVERSIBLE change in which 1 adult cell type is replaced by another
- can be physiological e.g. cervix or pathological e.g. Barrett’s (columnar lined) oesophagus
What is dysplasia?
precancerous cells which show the genetic and cytological features or malignancy, but not invading underlying tissue
N.B. increased nuclear- cytoplasmic ratio
What are 2 microscopic changes associated with reversible injury?
- fatty change e.g. liver bc of alcohol
- cellular swelling
What is necrosis?
irreversible confluent cell death associated with INFLAMMATION
What are the 4 types of necrosis?
- coagulative necrosis- cells keep their shape
- liquefactive necrosis- fluid filled spaces e.g. brain
- caseous necrosis- granular e.g. TB
- fat necrosis- e.g. acute pancreatitis- free fatty acids cause white spots
What is apoptosis?
- programmed cell death
- requires ATP
- NO INFLAMMATION
- can be physiological
What are causes of apoptosis?
- embryogenesis
- deletion of auto-reactive T cells in the thymus
- hormone-dependent e.g. endometrium
- cell deletion in proliferating populations e.g. gut
- irreparable DNA damage
What is necroptosis?
- programmed cell death associated w/ inflammation
- many causes e.g. viral infections
