Properties and Functional Aspects of the Enteric Nervous System

Abstract

The gut is a completely unique organ in that it has its own nervous supply. Gut functions such as motility, secretion and microcirculation are under the control of the enteric nervous system (ENS), which is embedded within the wall of the gut [5, 40, 41]. In addition there is a close interaction between the ENS and the enteric immune system; thus, neuro-immune interactions are important for the actions of many mediators of immunocompetent cells [4, 9]. The ENS is the largest accumulation of nerve cells outside the brain; in humans it consists of about 100 million neurons. They are organized into two main plexuses; the myenteric plexus located between the two muscle layers and the submucous plexus located between the circular muscle and the mucosa. In many, certainly in all large mammals, the latter consists of an inner and outer plexus. Myenteric neurons located between the longitudinal and circular muscle layers regulate mainly motility. Submucosal neurons situated between the submucosa and the mucosa are involved in the regulation of such mucosal processes as electrolyte resorption, mucus secretion, mucosal blood flow and neuroimmune interactions. In addition, both plexuses act in concert to coordinate secretion and motility.