AED - Cell Injury I - Week 1

Question 1

When a cell encounters an injurous agent, what happens?

What happens when the adaptive capacity of a cell is exceeded?

Answer 1

The cell adapts to preserve tissue viability.

Cell injury occurs as a result of adaptive capacity being exceeded.

Question 2

Name 8 common causes of cell injury/stress.

Answer 2

Hypoxia
Chemicals/drugs
Physical agents
Microbiological agents
Immunological agents
Genetic defects
Nutritional imbalances
Ageing

Question 3

Define atrophy.

Answer 3

Decrease in cellular size and organelles

Question 4

Define hypertrophy.

Answer 4

Increase in normal cell size

Question 5

Define hyperplasia.

Answer 5

Increase in normal cell number

Question 6

Define metaplasia.

Answer 6

Replacement of one cell type with another by differentation/proliferation

Question 7

Define dysplasia.

Answer 7

Abnormal change in cell shape/size

Question 8

Give an example of atrophy as it occurs in iris tissue, including the loss of what molecule in which cells, and what condition it results in.

Answer 8

Loss of melanosomes in iris pigment epithelial cells

Causes peripupillary atrophy

Question 9

What does pseudoexfoliation syndrome result in?

Answer 9

Deposition of exfoliative deposits in the iris.

Question 10

What can cause pseudoexfoliation syndrome?

Answer 10

Melanosome atrophy in the iris pigment epithelial layer

Question 11

List 4 common (but not exhaustive) causes of corneal epithelium hyperplasia.

Answer 11

Chemical and physical irritants
Microbial infections
Nutritional deficiency

Question 12

Name a possible cause of conjunctival epithelium dysplasia (a virus).

Answer 12

Human papilloma virus

Question 13

Are dysplasic cells morphologically unique to their original shape, or similar?

Answer 13

They retain some semblance to the original cell type

Question 14

Are dysplasic cells self-limiting?

Answer 14

Yesd

Question 15

Are dysplasic cells invasive?

Answer 15

No

Question 16

Define karyolysis.

Answer 16

Chromatin dissolution

Question 17

Define pyknosis.

Answer 17

Chromatin clumping

Question 18

Define karyorrhexis.

Answer 18

Chromatin fragmentation

Question 19

What happens to the cell and nucleus with cell injury (in general)?

Answer 19

The cell swells and nuclear chromatin clumps together

Question 20

Define apoptosis and the two types.

Answer 20

Active, programmed process of autonomous cellular dismantling that avoids eliciting inflammation.
Can be pathological or homeostatic.

Question 21

Define necrosis.

Answer 21

Passive, accidental cell death resulting from environmental perturbations with uncontrolled release of inflammatory cellular contents.

Question 22

Distinguish briefly between the effects of apoptosis and necrosis.

Answer 22

Necrosis can result in the release of inflammatory and degrading agents, causing surround tissue damage and inflammation.
Apoptosis occurs after cellular mechanisms are shut down and disassembled. Breakdown products are enclosed in a membrane, with little tissue disruption.

Question 23

Compare cell size in necrosis vs apoptosis.

Answer 23

Shrinks in apoptosis, swells in necrosis.

Question 24

List the four principle biochemical mechanisms of cell injury.

Answer 24

Mitochondria and their ability to generate ATP and ROS
Disturbance in calcium homeostasis
Damage to cellular membranes
Damage to DNA and protein misfolding

Question 25

List the two major pathays for apoptosis.

Answer 25

Mitochondrial intrinsic pathway

Death receptor extrinsic pathway

Question 26

hat is apoptosis initiated by?

Answer 26

Caspases

Question 27

List the passive process by which necrosis occurs.

Answer 27

Acute ATP depletion

Question 28

Name a technique to assay cell injury.

Answer 28

Detection of DNA fragments by labeling terminal ends.

Question 29

Ho can annexin V be used to image apoptosis?

Answer 29

It is exposed with membrane damage, fluorescently labeled annexin V antibodies can be administered.

Question 30

Are apoptosis and necrosis linked or mutually exclusive? Explain.

Answer 30

Linked.

Donor corneas show signs of both apoptotic and necrotic cell death after refrigeration, suggesting a link.

Question 31

What happens to the cell membrane in reversible (3) vs irreversible cell injury (2)?

Answer 31

Reversible - blebs form, aggregation of intramembranous particles, generalised swelling
Irreversible - myelin figures form, defects occur in cell membrane

Question 32

What happens to lysosomes in reversible (1) vs irreversible cell injury (1)?

Answer 32

Reversible - autophagy by lysosomes

Irreversible - rupture of lysosomes and autolysis

Question 33

What happens to mitochondria in reversible (2) vs irreversible cell injury (2)?

Answer 33

Reversible - swelling, small densities appear

Irreversible - swelling, large densities appear

Question 34

What happens to ribosomes and the ER in reversible (2) vs irreversible cell injury (2)?

Answer 34

Reversible - ER swelling, ribosome dispersion

Irreversible - ER lysis, ribosome dispersion

Question 35

What happens to the nucleus in reversible (1) vs irreversible cell injury (3)?

Answer 35

Reversible - chromatin clumps

Irreversible - pyknosis or karyoloysis, or karyorrhexis

Question 36

What strucure might form in cells with irreversible damage and where?

Answer 36

Myelin figures near the cell membrane