Cell Injury

Question 1

List possible causes of cell injury

Answer 1

• Oxygen deprivation / hypoxia
• Physical trauma (mechanical, temperature etc.)
• Chemical agents/ drugs
• Infectious agents (viruses, bacteria, parasites)
• Immunological reactions
• Genetic derangements
• Nutritional imbalances

Question 2

Which are the first changes to occur after cell injury? Which follow?

Answer 2

First biochemical changes, which are responsible for the morphological changes which are more subtle in onset and appear only when there is already considerable damage

Question 3

Describe the morphological changes which are characteristic of reversible cell damage

Answer 3

• Cell swelling
• Blebbing of the plasma membrane
• Detachment of ribosomes from ER
• Clumping of nuclear chromatin

Question 4

What are the biochemical changes responsible for the morphological changes in reversible cell injury?

Answer 4

• Decreased ATP generation
• Defects in protein synthesis
• Loss of cell membrane integrity
• Cytoskeletal damage
• DNA damage

Question 5

What are the two main features of reversible injury under the light microscope?

Answer 5

Cellular swelling (due to the failure of ion pumps)

Fatty change (appearance of lipid vacuoles in the cytoplasm)

Question 6

What causes the depletion of ATP?

Answer 6

Lack of oxygen/nutrients

Mitochondrial damage

Question 7

List the consequences of ATP depletion

Answer 7

• Ion pumps fail (energy dependant)
• Cellular metabolism is altered
• Influx of Ca++ into the cell (as pumps have failed)
• reduction of protein synthesis
• Mitochondrial damage
• hence further ATP depletion
• Accumulation of free radicals in the cell
• Damage to DNA and proteins induced by free radicals

Question 8

What occurs when the cell has passed the point of no return?

Answer 8

Cell death (due to irreversible injury)