Multisystem: Shock, Sepsis and Metabolic Syndromes · USMLE Step 1

A patient with anaphylactic shock develops severe bronchospasm and hypotension. Which mediator is primarily responsible?

  1. Acetylcholine
  2. Histamine
  3. Norepinephrine
  4. Vasopressin
Show answer and explanation

Correct answer: Histamine

Anaphylaxis involves massive mast cell degranulation with histamine release causing bronchoconstriction and vasodilation. Epinephrine reverses these effects.

Difficulty: Medium Question 9 of 19

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