Necrosis and apoptosis Flashcards
What occurs during oncotic necrosis?
- membrane blebs
- swelling of endoplasmic reticulum
- myelin figures
- nucleur condensation
- lysosome rupture
- swollen mitchondrian with amorphous densities
- and then fragmentation of cell membrane and nucleus
What is the role of calcium in cell injury?
- calcium = very tightly regulated
- calcium acts as an activator to enzymes e.g. ATPase
- accelerate reduction of ATP
- accelerate breakdown- so death
- cells will start changing shape- proteins activated by calcium
- lead to desruction of cell
What happens if there is an increase in calcium in a cell?
- membrane becomes more permeable
- mitochondria which normally stores it- damaged
- endoplasmic reticulum damaged
What is the role of ROS?
- e.g. o2, H2O2, OH-
- membrane lipid peroxidation
- DNA fragmentation
- Protein cross-linking and fragmentation
- they react with CM, proteins, DNA- breakdown cell
- Antioxidants neutralise
What is this showing?
- first picture- normal nucleus
- second:
- nuclei dark blue and small (pyknotic)
- over time get further degraded- Karyorrhectic cells
- some cells dont have a nucleus anymore (degaded) = Karyolytic
What is Coagulative necrosis?
- typical response to hypoxia, infarction or toxic injury
- preservation of cell outlines, coagulation of proteins (eosionphilic) with nuclear signs of necrosis
What is this showing?
- coagulative necrosis
- can only see outline/ no details
- can see some pyknosis and karyolysis
What type of necrosis is this presenting?
- Caseous necrosis
- chees-like, crumbling
- older lesion than coagulative
- may be calcified
What necrosis is this showing?
- Caseous necrosis
- normal tissue on left
- abnormal on right
- broken down by enzymes
- pink = cellular debris
What type of necrosis is this?
- Liquefactive = nectrotic tissue converted to fluid phase
- older lesion than coagulative
- loss of cell architecture
- CNS
- gross appearance in CNS = malacia
What type of necrosis is this?
- Liquefactive (lots of space seen)
What type of necrosis does this show?
- Gangrenous necrosis
- develops at distal extremeties or dependent portions of organs (where blood supply could be blocked)
Describe wet, gas and dry gangrene
What type of necrosis is this showing?
- Fat necrosis
- shows duodenum, pancreas and fat
- white = calcified fat
- fat cells go pink because of protein
What are the different types of fat necrosis?
- Nutritional - due to unsaturated fats and low antioxidants (yellow brown appearance of fat)
- Enzymatic- due to release of enzymes from inflamed pancreas into peri-pancreatic fat
- Saponification- calcify and turn to soap
- Traumatic- blunt trauma of fat over bony prominents
- Idiopathic
What are the triggers of apoptosis?
- binding ligands e.g. TNF
- stressors or injury from toxins or ROS
- withdrawal of growth factors
- DNA damage
- immune mediates injury (T lymphocytes, NK cell)
What are the extrinsic and intrinsic pathways of apoptosis?
E = binding of a ligand to death receptor
I = initiated by mitochondria
Explain the extrinsic pathway
- ligand binds to receptor
- Procaspase 8 activates caspase 8
- activates caspase 3
Explain intrinsic pathway
- damage to DNA
- procaspase 9 activates caspase 9
- activates caspase 3
What is this showing?
- apoptosis
