Adrenergic receptors bind to which neurotransmitter to cause sympathetic activation?

Adrenergic receptors bind to which neurotransmitter to cause sympathetic activation?

• A. Epinephrine
• B. Norepinephrine
• C. Acetylcholine
• D. Dopamine

Answer: (B)

Adrenergic receptors respond to catecholamines in the sympathetic system. The primary neurotransmitter released by most sympathetic postganglionic neurons that binds these receptors is norepinephrine. When norepinephrine attaches to alpha and beta adrenergic receptors on target tissues, it initiates the fight-or-flight responses like increased heart rate and vasoconstriction. Epinephrine can also activate adrenergic receptors, acting as a circulating hormone from the adrenal medulla, but the neurotransmitter directly released at sympathetic nerve endings is norepinephrine. Acetylcholine targets cholinergic receptors (nicotinic and muscarinic) and is linked to parasympathetic activity, not adrenergic activation. Dopamine interacts mainly with dopamine receptors, not adrenergic receptors.

Adrenergic receptors respond to catecholamines in the sympathetic system. The primary neurotransmitter released by most sympathetic postganglionic neurons that binds these receptors is norepinephrine. When norepinephrine attaches to alpha and beta adrenergic receptors on target tissues, it initiates the fight-or-flight responses like increased heart rate and vasoconstriction. Epinephrine can also activate adrenergic receptors, acting as a circulating hormone from the adrenal medulla, but the neurotransmitter directly released at sympathetic nerve endings is norepinephrine. Acetylcholine targets cholinergic receptors (nicotinic and muscarinic) and is linked to parasympathetic activity, not adrenergic activation. Dopamine interacts mainly with dopamine receptors, not adrenergic receptors.