Reversible cell injury

• Reversible cell injury occurs when the stress is mild to moderate and the cell can recover.
• Hypoxia is the most common cause of cell injury which is caused due to ischemia.

Mechanism of Reversible cell injury-

• Following mechanisms are responsible for reversible cell injury-

1. Decreased generation of cellular ATP—

• It occurs in both reversible & irreversible cell injury.
• ATP depletion to 5- 10 % of normal levels will induce cell injury.
• It may occur due to- 

1. Ischemia interruption in blood supply as well as hypoxia limits oxygen supply to the cell leading to decrease in ATP generation → necrosis.
2. Mitochondrial damage leading to decrease oxidative phosphorylation which causes decrease ATP generation → necrosis.

2. Intracellular lactic acidosis results in nuclear clumping due to low oxygen supply → anaerobic pathway → depletion of glycogen → accumulation of lactic acid & decease                     intracellular pH → nuclear clumping.

3. Damage to plasma membrane may occur due to-

1. Failure of sodium- potassium pump (Na⁺– K⁺ ATPase)  resulting in cell swelling (Hydropic swelling).
2. Failure of calcium pump  by increased sodium level where excess of calcium will move into the cell resulting in deposition of phospholipase & cell swelling.

4. Reduced protein synthesis–

• Due to hypoxia, ribosomes detach from endoplasmic reticulum & golgi apparatus which degrades into monosomes leading to decrease in protein synthesis.

ULTRASTRUCTURAL CHANGES OF REVERSIBLE CELL INJURY-

• Plasma membrane alterations in the form of blebbing & loss of microvilli.
• Myelin figures derieved from damage of the membranes (whorls of lamellated phospholipid and calcium)
• Mitochondrial swelling & small amorphous densities within mitochondria.