Autonomic nervous system and secretion across the intestinal mucosal surface.

Chloride secretion is important because it is the driving force for fluid movement into the intestinal lumen. The flow of accumulated fluid flushes out invading micro-organisms in defense of the host. Chloride secretion is regulated by neurons in the submucosal plexus of the enteric nervous system. Mechanosensitive enterochromaffin cells that release 5-hydroxytryptamine (5-HT) and activate intrinsic afferent neurons in the submucosal plexus and initiate chloride secretion. Mechanical stimulation by distention may also trigger reflexes by a direct action on intrinsic afferent neurons. Dysregulation of 5-HT release or altered activity of intrinsic afferents is likely to occur in states of inflammation and other disorders.