PHGY 210 Lecture Notes - Lecture 3: Swallowing, Enteric Nervous System, Thoracic Cavity
27 Nov 2015
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Document Summary
It is exposed to a negative intrathoracic pressure (-5 to -10 mmhg) Atmospheric pressure is higher than the esophagus so air is constantly sucked down into it. Intragastric pressure is positive (+5 to +10 mmhg) which results in gastric content being sucked up into the vacuum of the lumen of the esophagus. But this is prevented because the ues is tighly closed so it separates the atmospheric pressure of the pharynx from the body of the esophagus. During deglutition, these sphincters relax sequentially and allow for the bolus to move through without reflux of the stomach into the esophagus. Peristalsis: a wave of contraction moving over the wall of the organ, narrowing the lumen and setting up a gradient of pressure favouring aboral movement, each time we swallow, a single primary peristaltic wave is generated. It takes 8-10 seconds to be propagated the length of the esophagus: primary peristalsis is part of the deglutition reflexes.
