Cell death

Question 1

Name the 2 concurrent processes which cause necrosis

Answer 1

• Enzymatic digestion of the cell

- Denaturation of proteins

Question 2

What is necrosis?

Answer 2

Morphological changes that follow cell death

Question 3

Define the following:

1. Autolysis

2. Heterolysis

Answer 3

1. Lysosomal enzymes of the dying cell itself

2. Enzymes from infiltrating leukocytes

Question 4

Describe the morphological features of necrotic cells

Answer 4

• Increased eosinophilia
• Pyknosis = nuclear shrinkage
• Fragmentation of the pyknotic nucleus

Question 5

Which type of necrosis is being described?

• Dominant feature = denaturation of proteins
• In hypoxic cell death
• Preservation of cell outline

Answer 5

Coagulative necrosis

Question 6

Describe liquefactive necrosis

Answer 6

• Dominant feature = enzymatic digestion
• With focal bacteria and fungal infections
• Complete digestion of cells to liquid mass

Question 7

Which type of necrosis is being described?

• Complete obliteration of tissue architecture
• Surrounded by distinctive inflammatory cell border

Answer 7

Caseous necrosis

Question 8

Describe fat necrosis

Answer 8

Focal destruction of adipose tissue
Due to release of pancreatic enzymes
Fatty acids combine with calcium -> visible white chalky areas

Question 9

What is apoptosis?

Answer 9

Programmed cell death to eliminate host cells

Question 10

What are the morphological features of apoptosis?

Answer 10

• Cell shrinkage
• Chromatin condensation
• Phagocytosis of apoptotic cells

Question 11

What are some biological features of apoptosis?

Answer 11

• protein cleavage
• protein cross-linking
• DNA breakdown
• phagocytic recognition

Question 12

Describe the initiation stage of apoptosis

Answer 12

• By apoptotic stimuli
• Signals are transmitted across the plasma membrane to intracellular regulatory molecules
• Signals address targets within cells e.g. glucocorticoids, heat, viral infections

Question 13

What is able to suppress apoptosis?

Answer 13

• hormones
• growth factors
• cytokines

Question 14

What is able to activate apoptosis?

Answer 14

• Receptor ligand interaction

Question 15

What is the ultimate outcome of pro-apoptotic signals?

Answer 15

Cytochrome C release from mitochondria -> caspase cascade

Question 16

What occurs in the execution phase of apoptosis?

Answer 16

• Mediated by caspases
• Functional division into initiator and execution caspases
• Disruption of cytoskeleton
• Destruction of nuclear proteins

Question 17

Compare the histological changes in necrosis and apoptosis

Answer 17

Necrosis:
- Whole fields of cells affected
- Loss of cell borders with irregular fragmentation
- Swelling and loss of surface structures
Apoptosis:
- Individual cells affected
- Formation of round bodies
- Chromatin condensation
- Preservation of internal and external membranes

Question 18

Describe phagocytosis in apoptosis

Answer 18

• No release of pro-inflammatory breakdown products
• Ingestion by adjacent cells or tissue macrophages
• No scarring

Question 19

What is activation induced cell death?

Answer 19

Activated T-cells express enhanced levels of surface molecules that invoke apoptosis in a process of activation-induced cell death

Question 20

Out of necrosis and apoptosis, which involves inflammation?

Answer 20

Necrosis

Question 21

What happens to the cell size during:

1. necrosis
2. apoptosis

Answer 21

1. Enlarged, swelling

2. Reduced, shrinkage

Question 22

Name the 3 steps that happen to the nucleus in necrosis

Answer 22

• Pyknosis
• Karyorrhexis
• Karyolysis