End-Organ Damage Mechanisms · USMLE Step 1

Which pathophysiologic mechanism underlies organ damage in ischemia-reperfusion injury (e.g., after transient vessel occlusion and reperfusion)?

  1. Ischemia followed by a protective antioxidant surge
  2. Reperfusion-driven ROS burst and mitochondrial dysfunction causing cell death
  3. Immediate formation of dense fibrotic tissue
  4. Reactive hyperplasia of the endothelial cells
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Correct answer: Reperfusion-driven ROS burst and mitochondrial dysfunction causing cell death

Reperfusion after ischemia causes sudden ROS surge and mitochondrial dysfunction, triggering cell death (necrosis or apoptosis), inflammation, and tissue injury — an important mechanism in MI, stroke and organ transplantation.

Difficulty: Medium Question 13 of 20

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