Which one of the following sites is characterized by adrenergic neurohumoral transmission?: (A) Parasympathetic preganglionic fibers, (B) Sympathetic postganglionic fibers, (C) Sympathetic fibers in the adrenal medulla, (D) Synaptic fibers in the ecrine gland
Answer is C. The term neurohumoral means "nerve-blood." The only site in the ANS where neurohumoral transmission occurs is the adrenal medulla, where sympathetic nerve activity elicits the release of catecholamines into the blood.