Which of the Following "Pupil Events" is a True Statement

Question

Which of the following "pupil events" is a true statement?
A) Muscarinic activation causes mydriasis.
B) Muscarinic blockade induces miosis.
C) Alpha1 activation causes the radial muscle to contract, causing mydriasis.
D) Pupil diameter is determined by the rectus and oblique extrinsic eye muscles.

Accepted Answer

Alpha1 activation leads to the contraction of the radial (dilator) muscle in the iris, which results in mydriasis (dilation of the pupil). This is a sympathetic nervous system response.