Colonic Motility

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.

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. Table of Contents: Introduction / Regulatory Mechanisms / Colonic Motility in Health / Colonic Motility Dysfunction / References

Holland-Frei Cancer Medicine, Ninth Edition, offers a balanced view of the most current knowledge of cancer science and clinical oncology practice. This all-new edition is the consummate reference source for medical oncologists, radiation oncologists, internists, surgical oncologists, and others who treat cancer patients. A translational perspective throughout, integrating cancer biology with cancer management providing an in depth understanding of the disease An emphasis on multidisciplinary, research-driven patient care to improve outcomes and optimal use of all appropriate therapies Cutting-edge coverage of personalized cancer care, including molecular diagnostics and therapeutics Concise, readable, clinically relevant text with algorithms, guidelines and insight into the use of both conventional and novel drugs Includes free access to the Wiley Digital Edition providing search across the book, the full reference list with web links, illustrations and photographs, and post-publication updates

This multi-authored book covers most aspects of evaluation of gastrointestinal motility – a field that has been expanding in recent times largely due to advances in diagnostic modalities; coupled with this, new evidences supporting best practices have increased the interest among clinical gastroenterologists, researchers, teachers and trainees in gastrointestinal motility and its disorders. New advances in the field of evaluation of functional bowel diseases and motility disorders, such as high-resolution manometry, 24-h pH impedance monitoring, Bravo capsule pH-metry, barostat, balloon expulsion test, barium and MR defecography, biofeedback, hydrogen breath tests, motility capsule (smartpill) etc. have significantly expanded the scope and outcome of treating these disorders. The chapters have been contributed by a well-conversant group of experts from the global academia, including India, Singapore, Thailand, Korea and Australia, integrating the body of knowledge on evaluation methods with evidence of best practices for the management of motility disorders. A chapter on how to set-up a manometry laboratory provides key information for clinicians and researchers who are planning to start working in this area. With 11 chapters in the book supported with numerous tables, flow charts, schematic diagrams and images, professionals will find it an essential reading. ​

This issue of Gastroenterology Clinics of North America is on Gastrointestinal Motility Disorders. GI motility disorders are common reasons for patients to see gastroenterologists. Knowledge of the pathophysiology, evaluation and treatment of these disorders is important to appropriately care for patients with gastrointestinal motility disorders in clinical practice. The chapters of this issue will discuss key aspects of gastrointestinal motility disorders focusing on how they relate to practicing gastroenterologists and other health care providers. Current knowledge in the area as well as evolving concepts from clinical investigations and translational research from basic sciences will be discussed. The rapid explosion of new technology used in the evaluation of patients will be covered.

Clinical and Basic Neurogastroenterology and Motility is a state-of-the-art, lucidly written, generously illustrated, landmark publication that comprehensively addresses the underlying mechanisms and management of common adult and pediatric motility disorders. These problems affect 50% of the population and include conditions such as dysphagia, achalasia, gastroesophageal reflux disease, gastroparesis, irritable bowel syndrome (IBS), gas and bloating, SIBO, constipation and fecal incontinence. The book brings together international experts and clinician scientists, epitomizing their years of wisdom into a concise yet practical text that is delivered in two distinct sections, basic and clinical. It fulfills a large unmet need, and bridges a long-awaited knowledge gap among trainees, clinicians, scientists, nurses and technicians, earnestly engaged in this field. First of its kind text that covers both basic and clinical aspects, bridging the knowledge gap, and providing a bench to bedside approach for management of common disorders Discusses the latest concepts and basic principles of neurogastroenterology and motility, and how the gut and brain interact in the genesis of functional gastrointestinal and motility disorders Provides an illustrated and practical text on hot topics written by leading adult and pediatric gastroenterology experts across the globe Includes an accompanying more detailed web version of the text with free access to future podcasts

This book explains the pharmacological relationships between the various systems in the human body. It offers a comprehensive overview of the pharmacology concerning the autonomic, central, and peripheral nervous systems. Presenting up-to-date information on chemical mediators and their significance, it highlights the therapeutic aspects of several diseases affecting the cardiovascular, renal, respiratory, gastrointestinal, endocrinal, and hematopoietic systems. The book also includes drug therapy for microbial and neoplastic diseases. It also comprises sections on immunopharmacology, dermatological, and ocular pharmacology providing valuable insights into these emerging and recent topics. Covering the diverse groups of drugs acting on different systems, the book reviews their actions, clinical uses, adverse effects, interactions, and subcellular mechanisms of action. It is divided into 11 parts, subdivided into several chapters that evaluate the basic pharmacological principles that govern the different types of body systems. This book is intended for academicians, researchers, and clinicians in industry and academic institutions in pharmaceutical, pharmacological sciences, pharmacy, medical sciences, physiology, neurosciences, biochemistry, molecular biology and other allied health sciences.