AED - Cell Injury I - Week 1 Flashcards
When a cell encounters an injurous agent, what happens?
What happens when the adaptive capacity of a cell is exceeded?
The cell adapts to preserve tissue viability.
Cell injury occurs as a result of adaptive capacity being exceeded.
Name 8 common causes of cell injury/stress.
Hypoxia
Chemicals/drugs
Physical agents
Microbiological agents
Immunological agents
Genetic defects
Nutritional imbalances
Ageing
Define atrophy.
Decrease in cellular size and organelles
Define hypertrophy.
Increase in normal cell size
Define hyperplasia.
Increase in normal cell number
Define metaplasia.
Replacement of one cell type with another by differentation/proliferation
Define dysplasia.
Abnormal change in cell shape/size
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.
Loss of melanosomes in iris pigment epithelial cells
Causes peripupillary atrophy
What does pseudoexfoliation syndrome result in?
Deposition of exfoliative deposits in the iris.
What can cause pseudoexfoliation syndrome?
Melanosome atrophy in the iris pigment epithelial layer
List 4 common (but not exhaustive) causes of corneal epithelium hyperplasia.
Chemical and physical irritants
Microbial infections
Nutritional deficiency
Name a possible cause of conjunctival epithelium dysplasia (a virus).
Human papilloma virus
Are dysplasic cells morphologically unique to their original shape, or similar?
They retain some semblance to the original cell type
Are dysplasic cells self-limiting?
Yesd
Are dysplasic cells invasive?
No
Define karyolysis.
Chromatin dissolution
Define pyknosis.
Chromatin clumping
Define karyorrhexis.
Chromatin fragmentation
What happens to the cell and nucleus with cell injury (in general)?
The cell swells and nuclear chromatin clumps together
Define apoptosis and the two types.
Active, programmed process of autonomous cellular dismantling that avoids eliciting inflammation.
Can be pathological or homeostatic.
Define necrosis.
Passive, accidental cell death resulting from environmental perturbations with uncontrolled release of inflammatory cellular contents.
Distinguish briefly between the effects of apoptosis and necrosis.
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.
Compare cell size in necrosis vs apoptosis.
Shrinks in apoptosis, swells in necrosis.
List the four principle biochemical mechanisms of cell injury.
Mitochondria and their ability to generate ATP and ROS
Disturbance in calcium homeostasis
Damage to cellular membranes
Damage to DNA and protein misfolding
List the two major pathays for apoptosis.
Mitochondrial intrinsic pathway
Death receptor extrinsic pathway
hat is apoptosis initiated by?
Caspases
List the passive process by which necrosis occurs.
Acute ATP depletion
Name a technique to assay cell injury.
Detection of DNA fragments by labeling terminal ends.
Ho can annexin V be used to image apoptosis?
It is exposed with membrane damage, fluorescently labeled annexin V antibodies can be administered.
Are apoptosis and necrosis linked or mutually exclusive? Explain.
Linked.
Donor corneas show signs of both apoptotic and necrotic cell death after refrigeration, suggesting a link.
What happens to the cell membrane in reversible (3) vs irreversible cell injury (2)?
Reversible - blebs form, aggregation of intramembranous particles, generalised swelling
Irreversible - myelin figures form, defects occur in cell membrane
What happens to lysosomes in reversible (1) vs irreversible cell injury (1)?
Reversible - autophagy by lysosomes
Irreversible - rupture of lysosomes and autolysis
What happens to mitochondria in reversible (2) vs irreversible cell injury (2)?
Reversible - swelling, small densities appear
Irreversible - swelling, large densities appear
What happens to ribosomes and the ER in reversible (2) vs irreversible cell injury (2)?
Reversible - ER swelling, ribosome dispersion
Irreversible - ER lysis, ribosome dispersion
What happens to the nucleus in reversible (1) vs irreversible cell injury (3)?
Reversible - chromatin clumps
Irreversible - pyknosis or karyoloysis, or karyorrhexis
What strucure might form in cells with irreversible damage and where?
Myelin figures near the cell membrane
