Which neurotransmitter is released by the majority of postganglionic sympathetic neurons at their terminals on arteriolar smooth muscle?
- A Norepinephrine ✓
- B Acetylcholine
- C Epinephrine
- D Dopamine
Correct answer: A. Norepinephrine
Explanation
Most postganglionic sympathetic neurons are adrenergic and release norepinephrine, which acts mainly on vascular alpha-1 receptors to cause vasoconstriction. Acetylcholine is the exception at eccrine sweat glands and some skeletal muscle vasodilator fibres, not the rule. Epinephrine is secreted only by the adrenal medulla as a hormone and is not stored or released by sympathetic nerve terminals.
Reference: Ganong Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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