Mechanisms of cell injury Flashcards

1
Q

במה תלויה התגובה התאית לפגיעה?

A

סוג הפגיעה, משך הפגיעה, וחומרת הפגיעה

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2
Q

במה תלויה התוצאה בעקבות פגיעה?

A

סוג התא, מצבו, ויכולת האדפטציה שלו

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3
Q

perturbations in which elements cause cell injury?

A

one of five essential cellular elements:

  1. ATP production
  2. Mitochondrial integrity (independent of ATP prod.)
  3. Plasma Membrane integrity - ionic & osmotic homeostasis.
  4. Protein Synthesis - folding, degradation &re-folding
  5. Integrity of Nuclear Apparatus.
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4
Q

What are the six general pathways of intracellular cell injury?

A
  1. ATP depletion:
    - common both as a result of hypoxia & toxins.
    - lead to increased glycolysis, lactic acid accumulation, and intracellular acidosis.
    - No money to pay for ion transporters and protein makers.
  2. Mitochondrial Damage:
    - Causes:
    - Hypoxia & Toxins
    - Oxidative Stress
    - Increases cytosolic Ca.
    - Phospholipid Breakdown
    - Dissipates the electromotive force
    - Leakage of Cytochrome C (Apoptosis trigger)
  3. Influx of Calcium:
    - Across the PM or release from organelles.
    - The Calcium activates phospholipases, proteases, ATPases, and endonucleases (chromatin fragmentation)
  4. Accumulation of ROS:
    - Causes damage to lipids, proteins & nucleic acids.
    - Vitamin A&E are antioxidants that either block ROS formation or scavenge them.
    - Transition metals levels remain low thanks to protein binding ( ferritin, transferring, etc.)
  5. Defects in Membrane Permeability:
    - increased permeability of PM results in osmolarity change & enzymatic activity.
    - increased permeability of the mitochondrial membrane results in reduced ATP synthesis and can drive apoptosis via Cyt C.
    - increased lysosomal permeability releases potent enzymes and lowers pH.
  6. DNA & Proteins Damage:
    - too much damage to DNA activates apoptosis.
    - too many improperly folded proteins lead to stress response that also triggers apoptosis.
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5
Q

The transition from reversible to irreversible injury is difficult to identify, although two phenomena are associated with irreversible injury specifically.
What are they?

A
  • Inability to restore mitochondrial function.
  • Impropriate membrane function.

Leakage of cytosolic enzymes to the bloodstream may serve as a clinical marker of cell death.

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6
Q

Elevation of Creatinine Kinase and Troponin certain isoforms indicates:

A
  • Necrosis to Mayocardium cells
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7
Q

Elevation of Alkaline phosphatase specific isoform indicates:

A
  • Necrosis to Epithelial cells lining the bile ducts.
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8
Q

Elevation of alanine & aspartate transaminases indicates:

A
  • Necrosis to liver cells.
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9
Q

What is the difference between hypoxia and ischemia?

A
  • Hypoxia is reduced oxygen-carrying capacity
  • Ischemia is reduced blood flow
  • Ischemia causes hypoxia and tends to injure tissues faster than hypoxia ( because hypoxia does not interfere with substrates delivery and waste removal )
  • When the injury is considered reversible, re-oxygenation would let the cell recover, whereas in irreversible injury the cells will continue to die even though there is oxygen around.
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