Necrosis and apoptosis

Question 1

What occurs during oncotic necrosis?

Answer 1

• 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

Question 2

What is the role of calcium in cell injury?

Answer 2

• 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

Question 3

What happens if there is an increase in calcium in a cell?

Answer 3

• membrane becomes more permeable
• mitochondria which normally stores it- damaged
• endoplasmic reticulum damaged

Question 4

What is the role of ROS?

Answer 4

• 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

Question 5

What is this showing?

Answer 5

• 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

Question 6

What is Coagulative necrosis?

Answer 6

• typical response to hypoxia, infarction or toxic injury
• preservation of cell outlines, coagulation of proteins (eosionphilic) with nuclear signs of necrosis

Question 7

What is this showing?

Answer 7

• coagulative necrosis
• can only see outline/ no details
• can see some pyknosis and karyolysis

Question 8

What type of necrosis is this presenting?

Answer 8

• Caseous necrosis
  
  • chees-like, crumbling
  • older lesion than coagulative
  • may be calcified

Question 9

What necrosis is this showing?

Answer 9

• Caseous necrosis
  
  • normal tissue on left
  • abnormal on right
  • broken down by enzymes
  • pink = cellular debris

Question 10

What type of necrosis is this?

Answer 10

• Liquefactive = nectrotic tissue converted to fluid phase
  
  • older lesion than coagulative
  • loss of cell architecture
  • CNS
  • gross appearance in CNS = malacia

Question 11

What type of necrosis is this?

Answer 11

• Liquefactive (lots of space seen)

Question 12

What type of necrosis does this show?

Answer 12

• Gangrenous necrosis
  
  • develops at distal extremeties or dependent portions of organs (where blood supply could be blocked)

Question 13

Describe wet, gas and dry gangrene

Question 14

What type of necrosis is this showing?

Answer 14

• Fat necrosis
  
  • shows duodenum, pancreas and fat
  • white = calcified fat
  • fat cells go pink because of protein

Question 15

What are the different types of fat necrosis?

Answer 15

• 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

Question 16

What are the triggers of apoptosis?

Answer 16

• 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)

Question 17

What are the extrinsic and intrinsic pathways of apoptosis?

Answer 17

E = binding of a ligand to death receptor

I = initiated by mitochondria

Question 18

Explain the extrinsic pathway

Answer 18

• ligand binds to receptor
• Procaspase 8 activates caspase 8
• activates caspase 3

Question 19

Explain intrinsic pathway

Answer 19

• damage to DNA
• procaspase 9 activates caspase 9
• activates caspase 3

Question 20

What is this showing?

Answer 20

• apoptosis