BIO 203 Lecture Notes - Lecture 18: Gastrointestinal Tract, Gastric Pits, Soft Palate
29 Jun 2016
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Document Summary
Primary function is to conduct a bolus (mouthful) of food down to stomach. Striated muscle at the top of esophagus is under voluntary control- you choose when to swallow (first 3rd of esophagus) As food moves down waves of peristalsis move food bolus to stomach (involuntary smooth muscle contractions in lower esophagus) Allows unidirectional movement of food down alimentary canal. Little digestion occurs in esophagus, main function is peristalsis. Salivary amylase secreted in mouth continues to function digesting any starches/glycogen (a 1-4 linkages) First part of swallowing is voluntary-tongue pushes food against soft palate decreases space is mouth and creates a pressure gradient, in response to pressure gradient opening epiglottis and glottis (close flow to trachea and open flow to esophagus) In response to increasing pressure tonically contracted upper esophageal sphincter relaxes. Breathing is inhibited as bolus moves past closed airway (epiglottis closes to keep bolus out of airway) Protects epithelial lining of stomach from secretions and food.
