Anatomy and Physiology PDF Download

Author: J. Gordon Betts
Publisher:
ISBN: 9781947172807
Category :
Languages : en
Pages : 0

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Author: Samuel Osborne Habershon
Publisher:
ISBN:
Category :
Languages : en
Pages : 486

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Author: Sushil K. Sarna
Publisher: Biota Publishing
ISBN: 1615041516
Category : Medical
Languages : en
Pages : 159

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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.

Author: United States. National Weather Service
Publisher:
ISBN:
Category : Meteorology
Languages : en
Pages : 560

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Author: Ravinder Mittal
Publisher: Morgan & Claypool Publishers
ISBN: 1615043330
Category : Medical
Languages : en
Pages : 87

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Deglutition or a swallow begins as a voluntary act in the oral cavity but proceeds autonomously in the pharynx and esophagus. Bilateral sequenced activation and inhibition of more than 25 pairs of muscles of mouth, pharynx, larynx, and esophagus is required during a swallow. A single swallow elicits peristalsis in the pharynx and esophagus along with relaxation of upper and lower esophageal sphincters. Multiple swallows, at closely spaced time intervals, demonstrate deglutitive inhibition; sphincters remain relaxed during the entire period, but only the last swallow elicits peristalsis. Laryngeal inlet closure or airway protection is very important during swallow. Upper part of the esophagus that includes upper esophageal sphincter is composed of skeletal muscles, middle esophagus is composed of a mixture of skeletal and smooth muscles, and lower esophagus, including lower esophageal sphincter, is composed of smooth muscles. Peristalsis progresses in seamless fashion, despite separate control mechanism, from the skeletal to smooth muscle esophagus. The esophagus's circular and longitudinal muscle layers contract synchronously during peristalsis. Sphincters maintain continuous tone; neuromuscular mechanisms for tonic closure in the upper and lower esophageal sphincters are different. Lower esophageal sphincter transient relaxation, belching mechanism, regurgitation, vomiting, and reflux are mediated via the brain stem. Table of Contents: Introduction / Central Program Generator and Brain Stem / Pharynx-Anatomy, Neural Innervation, and Motor Pattern / Upper Esophageal Sphincter / Neuromuscular Anatomy of Esophagus and Lower Esophageal Sphincter / Extrinsic Innervation: Parasympathetic and Sympathetic / Interstitial Cells of Cajal / Recording Techniques / Motor Patterns of the Esophagus-Aboral and Oral Transport / Deglutitive Inhibition and Muscle Refractoriness / Peristalsis in the Circular and Longitudinal Muscles of the Esophagus / Neural and Myogenic Mechanism of Peristalsis / Central Mechanism of Peristalsis-Cortical and Brain Stem Control / Peripheral Mechanisms of Peristalsis / Central Versus Peripheral Mechanism of Deglutitive Inhibition / Neural Control of Longitudinal Muscle Contraction / Modulation of Primary and Secondary Peristalsis / Neural Control of Lower Esophageal Sphincter and Crural Diaphragm / Lower Esophageal Sphincter / Swallow-Induced LES Relaxation / Crural Diaphragm Contribution to EGJ and Neural Control / Transient LES Relaxation and Pharmacological Inhibition / Compliance of the EGJ / References

Author: University (Cambridge) Observatory
Publisher:
ISBN:
Category :
Languages : en
Pages : 332

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Author: William Blake
Publisher:
ISBN:
Category : Coinage
Languages : en
Pages : 136

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Author: Burkhard Madea
Publisher: CRC Press
ISBN: 1444181777
Category : Law
Languages : en
Pages : 292

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Estimation of the Time Since Death remains the foremost authoritative book on scientifically calculating the estimated time of death postmortem. Building on the success of previous editions which covered the early postmortem period, this new edition also covers the later postmortem period including putrefactive changes, entomology, and postmortem r

Author: John Walker
Publisher:
ISBN:
Category : English language
Languages : en
Pages : 788

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Author: Royal Observatory (Hong Kong)
Publisher:
ISBN:
Category : Geomagnetism
Languages : en
Pages : 646

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