The autonomic nervous system is organized into two functionally opposing divisions, sympathetic and parasympathetic, each built on a shared two-neuron architecture consisting of a preganglionic neuron originating in the central nervous system and a postganglionic neuron synapsing in a peripheral ganglion before innervating a target cell. Communication within this circuit relies on defined neurotransmitter-receptor pairings that differ by division and synaptic location: acetylcholine acting on nicotinic receptors at all ganglionic synapses, and either acetylcholine on muscarinic receptors (parasympathetic and select sympathetic postganglionic fibers) or norepinephrine on adrenergic receptors (most sympathetic postganglionic fibers) at the target cell. This neuroanatomical and neurochemical framework belongs to the study of neuroanatomy and underlies the functional opposition between stimulatory (sympathetic) and restorative (parasympathetic) physiological effects.
The autonomic nervous system is organized into two functionally opposing divisions, sympathetic and parasympathetic, each built on a shared two-neuron architecture consisting of a preganglionic neuro…