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Esophagel motility

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Physiology 3120
Tom Stavraky

Human Physiology Monday, April 5, 2010 “Gastro VII” Esophageal Motility (cont’d) • When a swallow occurs, there is inhibition of the tonic electrical activity, so sphincter relaxes, allowing food to pass through; hyoid bone also elevates, moving the glottis and the esophageal sphincter upwards (represents minor component of sphincter opening) • Body of the esophagus  Peristaltic contractions in response to swallowing; very similar to the contraction pattern/wave in the distal stomach to move food into the duodenum; in the stomach, the controlling mechanism for peristaltic contractions was the slow wave pattern; smooth muscle cells in the esophagus do NOT have a slow wave; vagus innervates at the top of the esophagus, and then the ENS transmits the impulse to progressively distal portions; but in order to produce peristalsis, need to increase the latency as you move down the esophagus (latency gets larger as you move down esophagus)  If something gets stuck, it gets dislodged by a phenomenon called secondary peristalsis; no stimuli for swallowing beyond the oral pharynx; occurs as a result of stretch receptors being activated by the presence of food in the esophagus, which then go on to activate the ENS, as well as a long-loop vago-vagal reflex  Last hurdle bolus has to overcome the entrance into stomach through lower esophageal sphincter (LES); the LES is not an anatomical sphincter – that is, it looks like any other part of the esophagus; pressure increases (i.e. has high muscle TONE) in the region of the LES, so it is tonically closed (seems to be due to an intrinsic property of the smooth muscle cells; when the bolus reaches it, it relaxes due to vagal activation (just as in the proximal stomach), so the neurotransmitter is nitric oxide Intestinal Motility (small & large) • Different types of contractile activity in the fed vs. fasted state (24-36hrs of fasting)  Fed state  Two basic types: (1) contractions which are segmental; orientated in time and space so as
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