Norepinephrine function includes which of the following effects?

• A. Neurotransmitter that lowers BP.
• B. Neurotransmitter and raises BP. Binds with adrenergic receptors in the sympathetic nervous system.
• C. Hormone that increases insulin secretion.
• D. Neurotransmitter that causes vasodilation in skeletal muscle.

Answer: (B)

Norepinephrine primarily acts as a neurotransmitter in the sympathetic nervous system and increases blood pressure by promoting vasoconstriction and enhancing cardiac output. It binds to adrenergic receptors—especially alpha-1 receptors on vascular smooth muscle, which causes vasoconstriction and raises systemic vascular resistance, and beta-1 receptors in the heart, which increases heart rate and contractility. This combination elevates blood pressure and supports the fight-or-flight response. It is not a substance that lowers blood pressure or a hormone that markedly increases insulin secretion, and its effect is not to cause vasodilation in skeletal muscle (that vasodilation is more characteristic of epinephrine acting on beta-2 receptors). So the best description is that norepinephrine is a neurotransmitter that raises blood pressure by binding adrenergic receptors in the sympathetic nervous system.