Cellular injury
- What is cellular injury?
- If cellular stress overcomes cell’s ability to adapt, then cell gets injured.
- 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.
- 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)
- 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
- 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.
- What will PaO2 and O2 sat be in anaemia?
- PaO2 and O2 sat will be normal in anaemia
- 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.
- 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.
- 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.
- What will PaO2 and O2 sat be in methemoglobinemia?
- PaO2 will be the same and O2 sat will reduce.
- 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.
- What are signs/symptoms of methemoglobinemia?
- Cyanosis with chocolate colored blood.
- What is treatment of methemoglobinemia?
1.2 Cellular injury
Cellular injury Page 2.1 - What is treatment of methemoglobinemia?
- IV methylene blue - it generates moderators that will reduce Fe3+
- 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
- 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)
- 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.