<prompt> Which one of the following sites is characterized by adrenergic neurohumoral transmission?Parasympathetic preganglionic fibersSympathetic postganglionic fibersSympathetic fibers in the adrenal medullaSynaptic fibers in the ecrine gland  <response>: 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. 