Neural regulation of transport. Three divisions of the autonomic nervous system are involved in regulation of intestinal function: (1) parasympathetic, predominantly through cholinergic stimulation of secretion through vagal input; (2) adrenergic stimulation of absorption through prevertebral and sympathetic ganglia; and (3) the enteric nervous system (ENS), which integrates and coordinates the neural activity of the epithelia, vasculature, and smooth muscle. The enteric system consists of sensory neurons responsive to intraluminal stimuli, interneurons, and secretomotor neurons releasing vasoactive intestinal polypeptide and acetylcholine. Additional neural inputs and outputs modulate the function of secretory neurons and the interaction of the ENS with the smooth muscle and with immune and paracrine cells that may also influence mucosal transport.