The Cellular injury

Cellular injury

  1. What is cellular injury?
  • If cellular stress overcomes cell’s ability to adapt, then cell gets injured.
  1. What does cellular injury depend on?
  • Type of stress
  • Severity
    Type of cell - neurons can withstand hypoxia only for 3-5mins. Skeletal muscle can withstand for a
    very long time.
  1. What are causes of hypoxia(low O2 delivery to tissue)?
  • ischemia,
  • hypoxemia (PaO2<60 mm Hg),
  • low O2 carrying capacity (ex - anaemia, CO poisoning, methmeglobinemia)
  1. What is shock? What are it’s causes?
    Shock is a generalized decreased perfusion of a vital organ. Can occur by hypovolemia,
    cardiogenic, spetic, neurogenic, anaphylactic causes
  1. What is Budd chiari syndrome?
  • Blockade of hepatic vein can result in hepatic infraction, aka budd chiari syndrome.
    Most common cause of budd chiari syndrome is polycythemia vera. Polycythemia vera is a disease
    with too much RBC which leads to clot formation. Another cause is lupus.
  1. What will PaO2 and O2 sat be in anaemia?
  • PaO2 and O2 sat will be normal in anaemia
  1. What will PaO2 and O2 sat be in CO poisoning?
  • PaO2 will be the same and O2 sat will reduce. CO binds to Hb 100 times stronger than O2.
  1. What are signs/symptoms of CO poisoning?
    Early sign is headache (ask a pt if he has headache if you suspect CO poisoning). Pt may have
    cherry red color skin.
  1. What is methemoglobinemia?
    Normally, Fe in hemoglobin is in 2+ state and can bind to O2. If it gets oxidized to 3+, it can’t bind
    to O2 and this is methemoglobinemia.
  1. What will PaO2 and O2 sat be in methemoglobinemia?
  • PaO2 will be the same and O2 sat will reduce.
  1. What are causes of methemoglobinemia?
    Oxidative stress - sulfa drugs, nitrate drugs. Also seen in newborns because their machinery to
    reduce Fe 3+ isn’t good.
  1. What are signs/symptoms of methemoglobinemia?
  • Cyanosis with chocolate colored blood.
  1. What is treatment of methemoglobinemia?
    1.2 Cellular injury
    Cellular injury Page 2.1
  2. What is treatment of methemoglobinemia?
  • IV methylene blue - it generates moderators that will reduce Fe3+
  1. What are consequences of low ATP in cell?
  • Lactic acidosis due to lots of glycolysis
  • Disrupted Na/K pump result in Na accumulation and resulting water retention in cell
  • Disrupted Ca pump result in Ca accumulation and random enzyme activation in cytosol
  1. What are reversible finding in cell of low ATP?
    Hallmark is cellular swelling - loss of microvilli, membrane blebing as it pulls away from the
    cytoskeleton, swelling of RER and ribosomes fall off (low protein synthesis)
  1. What are irreversible finding in cell of low ATP?
  • Hallmark is membrane damage. End result is cell death.
    Cellular enzymes leak out (liver enzyme in hepatitis and cardiac enzyme in MI) and intracellular Ca
    increases.
  • Cytochrome C from mitochondria leaks out to cytosol and activates apoptosis
  • Lysozome enzymes will leak out and digest the cells. Ca in cytosol activates them.