Lecture 3 - Cell death (tbc) Flashcards
What is the effect of reversible cell injury?
Decrease in cell function
What are the effects of irreversible cell injury?
In order:
Cell death due to biochemical alterations
Ultrastructural changes
Light microscopic changes
Gross morphological changes
What are the two types of cell death?
Necrosis
Apoptosis
What cellular stress is necrosis a response of?
Cell injury
Sustained reduction in ATP
Damage to lipids, proteins, nucleic acids
Inflammation
How is apoptosis signalled?
Mitochondrial damage causes leakage of cytochrome c, signalling the cell to die by apoptosis
When does apoptosis occur?
Accumulation of misfolded proteins
DNA damage
Inflammation
What cell injury can cuase either necrosis or apoptosis?
Inflammation
What does Ca+ influx do during cell injury/death?
Calcium influx activates enzymes such as ATPase, phospholipase, protease and endonuclease (damages chromatin). Ca2+ influx also directly activated caspases
What happens during necrosis?
Enzymatic digestion of cell
- Autolysis and heterolysis
- Denaturation of cellular protein
- Cell contents leak out
What nuclear damage can occur during necrosis?
Karyolysis - nuclear fading
Pyknosis - nuclear shrinkage
Karyorrhexis - nuclear fragmentation
What are the different morphological types of necrosis?
Coagulative
Liquefactive
Caseous
Fatty
Gangrenous
What is coagulative necrosis?
Necrosis where the tissue architecture retained
Where does coagulative necrosis occur?
Occurs in the heart and kidneys (commonly due to hypoxia)
What is liquefactive necrosis?
Necrosis where there is cellular destruction and pus formation
When does liquefactive necrosis occur?
Often caused by bacteria/fungal infection, also following brain ischaemia
What is caseous necrosis?
A combination of coagulative and liquefactive necrosis
What is the appearance of caseous necrosis?
Cheesy
Where does fatty necrosis occur?
Pancreas or breast
What is fatty necrosis caused by?
Caused by lipases
What is gangrenous necrosis a response to?
Severe hypoxia (eg frostbite) and subsequent bacterial infection
What is the cell morphology of necrosis?
Disruption of plasma membranes
What does necrosis invoke?
Invokes inflammatory response which ultimately leads to clearing of the necrotic material and healing
What is apoptosis?
“Cell suicide” - programmed cell death which can be either physiological or pathological
What is the cell morphology of apoptosis?
- Cell shrinkage
- Chromatin condensation
- Cytoplasmic blebs and apoptotic bodies
- Phagocytosis of apoptotic bodies by adjacent cells
- Membranes and organelles preserved
What are apoptotic cells phagocytosed by?
Macrophages
What are the differences in necrosis and apoptosis?
Necrosis: Always pathological, affects adjacent group of cells, cell size increase, passive, inflammatory reaction, plasma membrane disrupted.
Apoptosis: Either physiological or pathological, affect single cells, cell size shrunken, active, no inflammatory reaction, membrane intact
Apoptosis is characterized by
a) Reduced cell size AND disrupted cell membrane
b) Increased cell size AND disrupted cell membrane
c) Reduced cell size AND intact cell membrane
d) Increased cell size AND intact cell membrane
e) Inflammation
c) Reduced cell size AND intact cell membrane
Necrosis is characterized by
a) Reduced cell size AND disrupted cell membrane
b) Increased cell size AND disrupted cell membrane
c) Reduced cell size AND intact cell membrane
d) Increased cell size AND intact cell membrane
e) Fragmentation into oligonucleosome fragments
b) Increased cell size AND disrupted cell membrane
