Activation of sympathetic fibers in the choroid typically causes what vascular response?

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Prepare for the NBEO Ocular Anatomy Posterior Segment and Cranial Nerves Test. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Multiple Choice

Activation of sympathetic fibers in the choroid typically causes what vascular response?

Explanation:
When sympathetic fibers in the choroid are activated, they release norepinephrine that acts on alpha-1 adrenergic receptors on the arteriolar smooth muscle, causing contraction. This leads to vasoconstriction and a reduction in choroidal blood flow, which fits the body's overall pattern of maintaining blood pressure and redirecting blood during stress. Tachyphylaxis isn’t the typical response here, and vasodilation would require different (beta-adrenergic) actions that aren’t the main effect of sympathetic input to the choroid.

When sympathetic fibers in the choroid are activated, they release norepinephrine that acts on alpha-1 adrenergic receptors on the arteriolar smooth muscle, causing contraction. This leads to vasoconstriction and a reduction in choroidal blood flow, which fits the body's overall pattern of maintaining blood pressure and redirecting blood during stress. Tachyphylaxis isn’t the typical response here, and vasodilation would require different (beta-adrenergic) actions that aren’t the main effect of sympathetic input to the choroid.

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