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.

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

Three distinct types of contractions perform colonic motility functions. Rhythmic phasic contractions (RPCs) cause slow net distal propulsion with extensive mixing/turning over. Infrequently occurring giant migrating contractions (GMCs) produce mass movements. Tonic contractions aid RPCs in their motor function. The spatiotemporal patterns of these contractions differ markedly. The amplitude and distance of propagation of a GMC are several-fold larger than those of an RPC. The enteric neurons and smooth muscle cells are the core regulators of all three types of contractions. The regulation of contractions by these mechanisms is modifiable by extrinsic factors: CNS, autonomic neurons, hormones, inflammatory mediators, and stress mediators. Only the GMCs produce descending inhibition, which accommodates the large bolus being propelled without increasing muscle tone. The strong compression of the colon wall generates afferent signals that are below nociceptive threshold in healthy subjects. However, these signals become nociceptive; if the amplitudes of GMCs increase, afferent nerves become hypersensitive, or descending inhibition is impaired. The GMCs also provide the force for rapid propulsion of feces and descending inhibition to relax the internal anal sphincter during defecation. The dysregulation of GMCs is a major factor in colonic motility disorders: irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and diverticular disease (DD). Frequent mass movements by GMCs cause diarrhea in diarrhea predominant IBS, IBD, and DD, while a decrease in the frequency of GMCs causes constipation. The GMCs generate the afferent signals for intermittent short-lived episodes of abdominal cramping in these disorders. Epigenetic dysregulation due to adverse events in early life is one of the major factors in generating the symptoms of IBS in adulthood.

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 authors of the most cited neuroscience publication, The Rat Brain in Stereotaxic Coordinates, have written this introductory textbook for neuroscience students. The text is clear and concise, and offers an excellent introduction to the essential concepts of neuroscience. - Based on contemporary neuroscience research rather than old-style medical school neuroanatomy - Thorough treatment of motor and sensory systems - A detailed chapter on human cerebral cortex - The neuroscience of consciousness, memory, emotion, brain injury, and mental illness - A comprehensive chapter on brain development - A summary of the techniques of brain research - A detailed glossary of neuroscience terms - Illustrated with over 130 color photographs and diagrams This book will inspire and inform students of neuroscience. It is designed for beginning students in the health sciences, including psychology, nursing, biology, and medicine. - Clearly and concisely written for easy comprehension by beginning students - Based on contemporary neuroscience research rather than the concepts of old-style medical school neuroanatomy - Thorough treatment of motor and sensory systems - A detailed chapter on human cerebral cortex - Discussion of the neuroscience of conscience, memory, cognitive function, brain injury, and mental illness - A comprehensive chapter on brain development - A summary of the techniques of brain research - A detailed glossary of neuroscience terms - Illustrated with over 100 color photographs and diagrams