Cell Injury

Question 1

Give 6 causes of reversible cell injury

Answer 1

Oxygen deprivation
Physical agents
Chemical Agents/drugs
Immunologic reactions
Genetic Derangements
Nutritional imbalances

Question 2

Describe the processes that can cause cell injury via Oxygen deprivation

Answer 2

• Reduced blood flow = Ischaemia
• Inadequate oxygenation of the blood
• Decreased oxygen-carrying capacity of the blood

Question 3

Describe the processes that can cause cell injury via Physical Agents

Answer 3

• Mechanical trauma
• Temperature exteremes
• Radiation
• Electric shock

Question 4

Describe the processes that can cause cell injury via Chemical agents/drugs

Answer 4

• Hypertonic concentrations of simple chemicals e.g. glucose
• Poisons
• Pollutants
• Insectisides
• Therapeutic agents

Question 5

Describe the processes that can cause cell injury via Immunologic reactions

Answer 5

• Immune reactions to external agents

- Immune reactions to internal agents (autoimmune disease)

Question 6

Describe the processes that can cause cell injury via Genetic derangements

Answer 6

• Deficiency of functional/structural proteins - metabolic errors
• Influence the susceptibility of cells to injury

Question 7

Describe the processes that can cause cell injury via nutritional imbalances

Answer 7

• Can be excess or deficiency

Question 8

Describe tissue degeneration

Answer 8

Depletion of cellular energy stores, cellular swelling, organelle alteration
Reversible if damaging stimulus removed in early stages

Question 9

Describe the morphologic changes due to degeneration

Answer 9

Cellular swelling (due to failure of energy-dependent pump)
Fatty change (abnormal accumulation of neutral lipids due to excess production or reduced metabolism)

Question 10

Name two types of irreversible cell damage

Answer 10

Necrosis and Apoptosis

Question 11

Describe Necrosis

Answer 11

Always pathological
Cell membranes are damaged
Denatured intracellular proteins
Leakage of cellular contents

Question 12

Describe a way in which necrosis can be detected

Answer 12

Intracellular enzymes and proteins released can be detected in the blood.

Question 13

Describe depletion of ATP as a cause of necrosis

Answer 13

Reduced nutrient supply or damage of mitochondria

Question 14

Describe mitochondrial damage as a cause of necrosis

Answer 14

Caused by hypoxia and toxins
= reduced ATP production
= (something about cytochrome C)

Question 15

Describe calcium influx/homeostasis loss as a cause of necrosis

Answer 15

• Causes: ischaemia, toxins
  = Increased mitochondrial permeability
  = Activation of cellular enzymes

Question 16

Describe the accumulation of oxygen-derived free radicals as a cause of necrosis

Answer 16

Causes: Inflammation, Radiation

= Damage to lipids, proteins and DNA

Question 17

Describe defects in membrane permeability as a cause of necrosis

Answer 17

Causes: Ischaemia, toxins, viruses

= Reduced ATP production due to effects on mitochondria permeability

Question 18

Describe Apoptosis

Answer 18

Can by physiologic (during embryogenesis)/pathologic (DNA damage and viral infections)
Cell membranes are intact
No Inflammation

Question 19

Describe capase activation as a cause of apoptosis

Answer 19

Capase = enzyme that cleaves proteins
In event that they are activated, they break down cytoskeleton and proteins (activate endonuclease to deal with DNA)
(otherwise exist as an inactive proenzyme)

Question 20

Describe DNA and Protein breakdown as a cause of apoptosis

Answer 20

Causes: drugs, radiation, stress

- DNA is broken down by endonuclease that is activated by capases

Question 21

Describe membrane alterations as a cause of apoptosis

Answer 21

Plasma membrane alters stimulating recognition by phagocytes