The basis of this book is a ten-lecture course on the control of gastrointesti nal motility given each year to the final year undergraduate students in Physiology at Sheffield University. A naive thought led me to believe that the conversion of my lecture notes into the present book would be a relatively easy task. I now know differently. As there is no equivalent undergraduate course elsewhere that I know of, it would be dishonest of me to claim this book to be an undergraduate text. The comprehensive way in which I have dealt with the subject, together with the inclusion of the most up-to-date material, make the book more relevant to postgraduate students of physiology, medicine and related sciences who require an introduction to the field of gastrointestinal motility and its control. I have, however, attempted to present the current concepts on the physiological mechanisms regulating motility in a way which under graduates, as well as postgraduates, will find readable, informative and, hopefully, enjoyable.

This book first presents an overview on the chemical coding of the morphological neuron types described by Stach in the pig intestine. In doing so, we have pointed out the difference between the definitions of type I neurons given by Dogiel and Stach. Secondly, it provides a basis for the morpho-chemical classification of human enteric neurons as revealed by their immunoreactivity for neurofilaments and several neuroactive substances or related markers.

A conspicuous portion of the peripheral nervous system is part of the 'vegetative nervous system'; it includes all the neurons which innerv ate the viscera, salivary and lacrimal glands, the heart and blood vessels, all other smooth muscles of the body, notably the intrinsic muscles of the eye and the muscles of the hair. Only part of the system belongs to the peripheral nervous system: it has also its own nuclei and pathways in the central nervous system. The distinction between visceral and somatic functions is a very old one in our culture. With the development of neurology the notion of a widespread nervous control of body functions emerged. Winslow (1732) used the term nervi sympathici majores for those nerves, which he thought to carry about 'sympathies' and then co ordinate various viscera's functions. His was an anatomical break through, which obscured Willis' 'intercostal nerve' and Vesalius 'cranial nerve'. The notion was developed among others by John stone (1764) who arrived, with the aid of some very accurate anatomical observations, at the problem of the nervous influence on motion and sensitivity of viscera. By the end of the eighteenth century, it was clear, with Bichat (1800), that what he called 'sympa thetic nervous system' (and his pupil Reil, a few years later, 'vegeta tive nervous system ') controlled visceral functions (fa vie organique), whereas somatic functions (fa vie animafe) were under direct control from the brain and spinal cord.

The enteric nervous system (ENS) is a complex neural network embedded in the gut wall that orchestrates the reflex behaviors of the intestine. The ENS is often referred to as the “little brain” in the gut because the ENS is more similar in size, complexity and autonomy to the central nervous system (CNS) than other components of the autonomic nervous system. Like the brain, the ENS is composed of neurons that are surrounded by glial cells. Enteric glia are a unique type of peripheral glia that are similar to astrocytes of the CNS. Yet enteric glial cells also differ from astrocytes in many important ways. The roles of enteric glial cell populations in the gut are beginning to come to light and recent evidence implicates enteric glia in almost every aspect of gastrointestinal physiology and pathophysiology. However, elucidating the exact mechanisms by which enteric glia influence gastrointestinal physiology and identifying how those roles are altered during gastrointestinal pathophysiology remain areas of intense research. The purpose of this e-book is to provide an introduction to enteric glial cells and to act as a resource for ongoing studies on this fascinating population of glia. Table of Contents: Introduction / A Historical Perspective on Enteric Glia / Enteric Glia: The Astroglia of the Gut / Molecular Composition of Enteric Glia / Development of Enteric Glia / Functional Roles of Enteric Glia / Enteric Glia and Disease Processes in the Gut / Concluding Remarks / References / Author Biography

The long tube that makes up the gastrointestinal tract is composed of a variety of tissue types and is the largest internal organ of the body. Its main function is to digest food and absorb the released nutrients. Furthermore, it is subdivided into functionally distinct regions that each mediate one of a variety of actions upon the food consumed, including ingestion, propulsion, secretion, digestion, absorption and expulsion. Autonomic neuronal circuitry is intimately involved in controlling many of these multiple functions of the gut, making it an appealing subject for the study of neuroscientists. This book reviews the state of current knowledge on the innervation of the gut by the enteric nervous system, and its interface with the extrinsic innervation, from a number of different perspectives, with the aim of providing a comprehensive and accessible account of the subject.