Pathology: Necrosis and Apoptosis

Question 1

Define hypertrophy

Answer 1

An increase in cell size

Question 2

Define hyperplasia

Answer 2

An increase in cell numbers

Question 3

Define atrophy

Answer 3

Reduction in cell size

Question 4

Define hypoplasia

Answer 4

A below-normal number of cells

Question 5

What factors overwhelm cell stress coping mechanisms such as hyperplasia and hypertrophy?

Answer 5

• Rapidity of stress

- Quantity of stress

Question 6

What are the 2 possible outcomes of the cell stress coping mechanisms being overwhelmed?

Answer 6

• Apoptosis

- Necrosis

Question 7

Describe necrosis

Answer 7

• Requires no energy
• Always pathological
• Uncontrolled cell death

Question 8

List the types of necrosis

Answer 8

• Coagulative necrosis
• Liquefactive necrosis
• Caseous necrosis

Question 9

Describe coagulative necrosis

Answer 9

• The cell outline is preserved
• So the tissue still has some structure
• Common with hypoxic, ischemic/infarction injury
• Cells are consumed by enzymes
• Doesn’t occur in the brain
• Cell is NOT destroyed by proteolysis via its enzymes

Question 10

What kinds of injury commonly causes coagulative necrosis?

Answer 10

• Hypoxic

- Ischemic, infarctions

Question 11

Describe liquefactive necrosis

Answer 11

• Cells form a liquid (no cell structure remains)
• Pus
• Associated with localised bacterial/fungal infections
• Brain necrosis is liquefactive
• After/if pus clears leaves a cavity

Question 12

Describe caseous necrosis

Answer 12

• Cheesy necrosis
• Granulomatous inflammation with central necrosis
• Associated with TB

Question 13

Define apoptosis

Answer 13

Programmed cell death in response to specific signals

Question 14

Describe apoptosis

Answer 14

• Requires energy
• Can be physiological or pathological
• Can be triggered by intrinsic or extrinsic factors
• Mechanism relies on caspase cascade

Question 15

Give examples of pathological apoptosis

Answer 15

• Some autoimmune disorders
• Infective disease
• Cancer
• In response to trauma

Question 16

Give an example of physiological apoptisis

Answer 16

• Growth and development
  e. g. finger development
• Removal of self-reactive lymphocytes
• Involution of the uterus

Question 17

Describe the extrinsic pathway for apoptosis

Answer 17

• Initiated by the activation of an death receptor (Fas or TNFR)
• The fas receptor is activated by a fas ligand on another cell (often a type of T-Lymphocyte)
  OR
• The TNF receptor (TNFR) can is activated by TNF
• Both mechanisms are mediated by fas associated death domain (FADD)
• Causes a caspase cascade

Question 18

Describe the mitochondrial mechanism for the intrinsic pathway for apoptosis

Answer 18

• Normally cell survival signals promote anti-apoptotic molecules in the mitochondrial membrane
• These inhibit Bax, Bak
• When the signals stop the Bax is free to form channels in the membrane allowing the contents to escape
• Cytochrome C escapes

Question 19

Describe the role p53 plays in apoptosis

Answer 19

• Involved at cell cycle checkpoints
• Checks for errors in DNA
• If error found, repair is attempted
• If it fails then apoptosis is induced

Question 20

List the risks of not having enough apoptosis

Answer 20

• Cancer

- Autoimmune disease

Question 21

List the risks of having too much apoptosis

Answer 21

• Neurodegenerative disorders

-

Question 22

Describe the morphological changes that occur during apoptosis

Answer 22

• Cell shrinks
• Pyknosis (irreversible chromatin condensation)
• Nucleus breaks up
• Apoptotic blebs form
• Apoptotic bodies (blebs after they break off)

Question 23

What cell type phagocytose apoptotic bodies?

Answer 23

Macrophages

Question 24

What are the causes of cellular aging

Answer 24

• Oxidative stress

- Accumulation of metabolic by-products