Chapter 15 - Enteric Nervous System: Brain-in-the-Gut

Abstract

The enteric nervous system (ENS) is an independent “brain-in-the-gut” that integrates gastrointestinal motility, secretion, and blood flow into homeostatic patterns of gut behavior that have susceptibility to becoming clinically disordered. Heuristic models for the ENS are the same as for all independent integrative nervous systems, whether in the mammalian brain and spinal cord or in invertebrate animals. The ENS coordinates and organizes the behavior of the musculature, secretory glands, and vascular system, in each of the specialized organs of the gastrointestinal tract, into meaningful behavior of each organ. Propulsive motility occurs as a contractile complex with two linked components based on neurogenically controlled contractile behavior of the longitudinal and circular muscle coats. Linked propulsive components consist of a propulsive segment connected in the direction of propulsion with a receiving segment. A “hardwired” polysynaptic circuit in the ENS is responsible for all propulsive motility in the tubular organs. This circuit occupies the lowest complexity level of the hierarchical organization of neural motility control. Networks in the ENS contain central pattern generators (CPGs), which activate the basic circuit in recurrent fashion to generate motility patterns linked with intestinal secretion.