Sympathomimetics · Pharmacology

Which sympathetic effect is mediated by the Alpha-1 receptor in the eye?

  1. Miosis (pupil constriction)
  2. Cycloplegia (loss of accommodation)
  3. Mydriasis (pupil dilation)
  4. Increased tear production
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Correct answer: Mydriasis (pupil dilation)

Alpha-1 receptors are located on the radial (dilator) muscle of the iris. Stimulation causes contraction of this muscle, leading to mydriasis. Unlike anticholinergic drugs, sympathomimetics do not typically cause cycloplegia.

Difficulty: Medium Question 19 of 20

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