Cell Injury

Question 1

What are the 4 key events in Cell injury?

Answer 1

1. ATP depletion
2. Accumulation of intracellular calcium
3. Accumulation of oxygen radicals
4. CM damage

Question 2

Discuss ATP depletion

Answer 2

Occurs due to hypoxia, ischemia or mitochondrial damage.

Question 3

Discuss hypoxia

Answer 3

An oxygen deficiency in cells or tissues. Caused by inadequate oxygen carrying capacity of blood from cardiorespiratory failure.

Question 4

What is ischemia?

Answer 4

Loss of blood supply to cells because of arterial blockage or impaired venous drainage.

Question 5

Describe the pathogenesis of hypoxic cell injury.

Answer 5

O2 deficiency, decrease in OP in mitochondria, decrease in ATP, Recuced activity in Na/K pump (Cell swelling), Switch to anaerobic glycolysis (lactic acid buildup), pH drop leads to protein destruction and further depletion of ATP.

Question 6

Discuss reperfusion injury

Answer 6

Restoration of blood flow after ischemia can further damage tissue.

Question 7

Discuss the loss of calcium homeostasis.

Answer 7

1. Calcium normally sequestered in mitochondria and ER.
2. Homeostasis maintained by energy-dependent Calcium/Magnesium ATPases.
3. Intracellular calcium spikes with loss of ATP
4. High intracellular calcium activates degradative enzymes in cell.

Question 8

Discuss ROS.

Answer 8

Reacts with membrane phospholipids and damages cellular proteins and DNA.

Question 9

What 5 things combat ROS damage?

Answer 9

1. Gluthatione enzymes
2. Vitamins A,C and E
3. Catalase (peroxisomes)
4. Superoxide dismutases
5. Iron and copper binding proteins.

Question 10

What are the two key events of Cell death?

Answer 10

1. Irreversible mitochondrial dysfunction

2. Severe membrane hyperpermeability.

Question 11

Why is cell swelling a sign of morphological injury?

Answer 11

1. Increase in size due to accumulation of water

2. Reflects loss of ionic and volume control at CM

Question 12

What are 5 ultrastructural changes in cell injury

Answer 12

1. Dilation of ER
2. Dissociation of ribosomes from rER
3. Dilation of mitochondria
4. Lucency of cytoplasm
5. CM alterations

Question 13

Is necrosis reversible?

Answer 13

NO

Question 14

Histologically describe necrosis

Answer 14

Increased cytoplasmic eosinophilia;

1. Denatured proteins
2. Decreased basophilia from dispersal of ribosomes

Question 15

Discuss the 3 nuclear changes.

Answer 15

1. Pyknosisz: shruken, basophilic nucleus
2. Karyorrhexis: Fragmented nucleus, loss of nuclear membrane
3. Karyolysis: Dissolution of nucleus