Which of the following is an effect of increased sympathetic tone on the uterus?

• A. Inhibition of contraction
• B. Contraction
• C. Vasodilation
• D. Sensation from uterine cervix

Answer: (B)

Autonomic regulation of uterine smooth muscle: when the sympathetic nerves activate, norepinephrine acts on adrenergic receptors in the myometrium. Activation of alpha-adrenergic receptors tends to increase contractile activity, so increased sympathetic tone promotes contraction. Although beta-adrenergic (especially beta-2) stimulation can relax uterine muscle, the net effect emphasized here is contraction due to alpha-receptor–mediated influence. The other options don’t fit as direct outcomes of sympathetic tone in the uterus—vasoconstriction is the typical vascular response, not vasodilation, and sensation from the cervix isn’t a direct smooth-muscle response to sympathetic activity.