[A] 1.38 Necrosis & Apoptosis

Question 1

Give the forms of necrosis

Answer 1

• Death
• Necrosis
• Necrobiosis
• Apoptosis (active process)

Question 2

Necrosis

Answer 2

Localised irreversible cessation of life in the living organism

• Morphological changes due to enzymatic degradation process in the injured cells

Question 3

Responses of cells to injury is dependent on…

Answer 3

• ​Cell type
• Injury type

Question 4

Give the responses of cells to injury

Answer 4

• Adaptation
• Degeneration
• Cell death

Question 5

Responses to injuries: Degeneration of the cell may be due to…

Answer 5

• Damage beyond adaptation capacity
• Severe/longlasting injury
• Malnutrition
• Mutation in important cell elements

Question 6

Stages of cell reaction

Answer 6

• Reversible stage: Can be repaired, normal function returns
• Irreversible stage: “Point of no return” → Cell death

Question 7

Give the types of cell death

Answer 7

• Physiological
• Passive
• Regulated
• Active

Question 8

When is physiological cell death seen?

Answer 8

• Embryonic development
• In skin cells & enterocytes

Question 9

Passive cell death

Answer 9

Necrosis

• The cell stops the vital functions
• Due to stimuli

Question 10

Regulated cell death

Answer 10

Necrobiosis

Question 11

Active cell death

Answer 11

Apoptosis

• Elimination of unwanted cell
• “Suicide” of the damaged cell

Question 12

What can necrosis affect?

Answer 12

• Cell elements
• Single cells
• Tissue parts
• Whole tissues
• Circumscribed areas of organs
• Whole organs
• Body parts
• Damaged tissues

Question 13

Give the categories of necrosis localisation

Answer 13

• Focal
• Regional
• Multifocal
• Massive
• Zonar

Question 14

Causes of necrosis

Answer 14

• Acquired - External/Internal
• Genetically programmed

Question 15

Acquired external necrosis

Answer 15

• Mechanical trauma (Blood vessels)
• Thermal effects (Burns & frostbites)
• Chemical (Acids & bases)
  
  • Coagulation & colliquation of proteins
• Toxins
  
  • Inhibition of enzymes
• Pathogens

Question 16

Acquired internal necrosis

Answer 16

• Hypoxia
  
  • Ischaemia, hypoxaemia, prestasis, stasis
• Trophoneurotic disorders
  
  • Injury, paralysis of nerves
• Pancreatic enzymes (lipase)

Question 17

Ultrastructural signs of necrosis

Answer 17

• Ribosomes detach from ER
• Mitochondria and other organelles are swollen
• Membranes are fragmented
• Reduced density of chromatin

Question 18

Histopathological signs of necrosis

• Nucleus
  
  • Hyperchromatosis of membrane
  • Karyopycinosis
  • Karyorrhexis
  • Karyolysis
• Cytoplasm
  
  • Glycogen disappears
  • Increased eosinophilia
  • Cytoplasmolysis

Question 19

Necrosis: Macroscopic changes

Answer 19

• Coagulation necrosis and special forms
  
  • Zenker necrosis
  • Caseation
  • Liponecrosis
• Colliquation necrosis

Question 20

Coagulation necrosis

Answer 20

• In the cytoplasm: Protein denaturation
• IC space: Denaturation due to lysosomal enzymes leaving cels
• Nuclear changes
• Occurence:
  
  • Liver, Kidney & spleen
• Causes:
  
  • Bacterial toxins

Question 21

Pathological signs of coagulation necrosis

Answer 21

• Sharp edges
• Elevated surface
• Dry cut surface
• Driable
• Colour: Dependent on blood content

Question 22

Special forms of coagulation necrosis

Answer 22

• Zenker necrosis
• Caseation
• Liponecrosis
• Blackleg disease (muscles & clostridia)

Question 23

Zenker necrosis: Characters

Answer 23

Necrosis of the contractile elements of muscle cells

• Cooked meat-like
  
  • Pale & dry

Question 24

Zenker necrosis: Causes

Answer 24

• Nutrition
  
  • Se or Vit. E deficiency
• Inproper circulation
  
  • Vasoconstriction
  • Improper functional hyperaemia
• Physical effects
  
  • Burns, frost & trauma

Question 25

Caseation

Answer 25

• Fatty infiltration before necrosis
• Lipochromes stain the necrotic mass
• Tuberculosis & Pseudotuberculosis

Question 26

Colliquation necrosis

Answer 26

• Enzymatic effect following the disintegration of cells
• Not too much protein
• Necrotic area:
  
  • Pulpy
  • Smeary

Question 27

Colliquation necrosis can be caused by…

Answer 27

Strong alkalic pH

Question 28

Coagulation necrosis + Secondary colliquation (heterolysis) →

Answer 28

Colliquation necrosis

Question 29

Give the consequences of necrosis

Answer 29

1. Regeneration
2. Calcification
3. Sequestration
4. Cicatrix (organisation)
5. Lysis
6. Desquamation, erosion & ulceration
7. Secondary infection

Question 30

Apoptosis: Causes

Answer 30

• Physiological:
  
  • Removal of unnecessary cells & tissue homeostasis
  • Removal of defective cells (genetic defects)
• Biochemical Effects:
  
  • Activated caspases (cysteine proteases)

Question 31

Answer 31

• Necrosis: Swollen
• Apoptosis: Shrunken

Question 32

Answer 32

• Necrosis: Pyknosis → Karyorrhexis → Karyolysis
• Apoptosis: Breaks into fragments

Question 33

Answer 33

• Necrosis: Damaged
• Apoptosis: Intact, different structure

Question 34

Answer 34

• Necrosis: Enzymatic lysis, get out of the cell
• Apoptosis: Intact, inside apoptotic bodies

Question 35

Answer 35

• Necrosis: Often
• Apoptosis: None

Question 36

Answer 36

• Necrosis: Always pathologic
• Apoptosis:
  
  • Often physiological, elimination of extra cells
  • Pathologic after cell damage