The activities of the Gastro-Intestinal Tract (GIT) are under neural and hormona control for proper coordination amongst different parts. The gastrointestinal tract is innervated by intrinsic nerves as well as by extrinsic nerves.
The intrinsic neural system, also called the enteric neural system consists of (i) Meissner’s plexus situated in the submucosa and (ii) Auerbach’s plexus situated in the muscular layer. The enteric neural system controls most of the gastrointestinal functions like secretion and motility.
The extrinsic innervation of the gut consists of parasympathetic and sympathetic nerves which can modify the activity of intrinsic neural system in response to reflex activity initiated by GIT or-from other body parts.
The sight, smell and the presence of food in the oral cavity can stimulate the secretion of the saliva through vagus nerve. Gastric and intestinal secretions are also stimulated by neural signals. The muscular activity of different parts of the alimentry canal can also be moderated by neural mechanisms, both local and through CNS.
Hormonal control of the secretions of digestive juice is carried out by the local hormones produced by the gastric and intestinal mucosa. These include gastrin (stimulate release of gastric juice), enterogastrone (inhibits gastric secrection and motility), secretin (decreases gastric secretion), duodocrinin (stimulate Brunner's gland) etc.
