Question

chapter 14 check your understanding question 8
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which of the following is an effect of norepinephrine binding to beta 2 adrenergic receptors?

vasoconstriction

vasodilation

an increase in heart rate

lipolysis

Explanation:

To determine the effect of norepinephrine binding to beta - 2 adrenergic receptors, we recall the physiological effects of this interaction. Beta - 2 adrenergic receptors, when activated by norepinephrine (or epinephrine), are associated with smooth muscle relaxation in blood vessels (especially in skeletal muscle vasculature), which leads to vasodilation. Vasoconstriction is more associated with alpha - adrenergic receptor activation. An increase in heart rate is mainly due to beta - 1 adrenergic receptor activation. Lipolysis is associated with beta - 3 adrenergic receptors (in adipose tissue) or other pathways, not primarily beta - 2 in the context of this question. So the correct effect is vasodilation.

Answer:

B. vasodilation (assuming the options are labeled as A. vasoconstriction, B. vasodilation, C. an increase in heart rate, D. lipolysis)