L4 Cell death

Question 1

Karyolysis

Answer 1

Digestion and progressive fading of the nucleus

decreased basophilia from DNA breakdown

Question 2

Karyorrhexia

Answer 2

Fragmentation of the nuclear chromatin

Question 3

Pyknosis

Answer 3

clumping of chromatin

nuclear shrinkage and increased basophilia

Question 4

Coagulative Necrosis

Answer 4

Denaturation> Digestion
Hard boiled egg
Nucleus is lost, architecture of the cells preserved
Solid organs except brain
Due to severe ischaemia-blockage to blood to a solid organ
Most common type

Question 5

Liquifactive Necrosis

Answer 5

Digestion> Denaturation 
Complete digestion of dead cells 
Infection (bacterial anf fungal) 
−	Ischemia in brain-necrotic area becomes fluid-filled cyst
Brain Liquifactive necrosis

Question 6

Caseous Necrosis

Answer 6

combination between coagulative and liquifactive necrosis
TB
Tissue architecture destroyed
− Fragmented lysed cells with amorphous granular appearance

Question 7

Fat Necrosis

Answer 7

− Enzymes liquefy membranes of fat cells
− Release fatty acids which combine with calcium to cause patchy white lesions (fat saponification)
− Most common in acute pancreatitis

Question 8

Fibrinoid Necrosis

Answer 8

leakage of fibrin and inflammatory cells

− Occurs in blood vessels in response to deposition of immune complexes

Question 9

Gangrenous Necrosis

Answer 9

lower limb that has lost its blood supply

may accompany a bacterial infection-wet gangrene

Question 10

Morphological features of necrosis

Answer 10

Appearance of necrotic lesion is influenced by the balance between coagulative and liquefactive

− Increased eosinophiilc staining-denatured protein and loss of RNA-> only pink stain-binding to proteins in the cytoplasm
− Vascuolation-digested cytoplasmic organelles
− Swelling of ER and mitochondria
− Myelin figures-wholes of phospholipid from damaged membranes
Membrane is breaking down and has a charge-> curls up= myelin figures
− Discontinuous plasma and organelle membranes- loss of integrity
− Nuclear change due to breakdown of DNA and chromatin

Question 11

Cause of apoptosis

Physiological induction of apoptosis

Answer 11

− Embryogenesis-webbing of digits
− Involution: shrinking of cells after pregnancy
− Elimination of cells that have reached their ‘used be date’
− Self-reactive T-lymphocytes-random cells

Question 12

Cause of apoptosis

Pathological induction of apoptosis

Answer 12

• DNA damage
• Accumulation of misfolded protein
• Infections lead to cell death
• Pathologic Atrophy

Question 13

Differences between apoptosis and necrosis

Answer 13

inflammatory response
A: pathological and physiological response
genetically directed

N: pathological
catastrophic homeostatic failure
controlled vs messy