When do these occur? V: occurs after ingestion. P: after voluntary phares when bolus enters oropharynx. E: last What initiates each phase? V: ingestion of food. P: arrival of bolus @ entryway to oropharynx. E: presence of bolus in esophagusWhat part of the brain controls this process? V: controlled by cerebral cortex (primarily temporal lobes & motor cortex of frontal lobe). P: tactile receptors around fauces stimulated by bolus & initiate nerve signals along sensory neurons to swallowing center in medulla oblongata [aka medulla oblongata]. E: ???Know the events that occur in each phase (see Figure 26.8). V: ingested materials & saliva mix in oral cavity, chewing forms bolus that’s mixed & manipulated by tongue & pushed superiorly against hard palate, transverse palatine folds in hard palate help direct bolus post. to oropharynx. P: tactile sensory receptors send nerve signals to swallowing center; bolus passes quickly & involuntaryily through pharynx to esophagus, sequential contraction of pharyngeal constrictors decrease diameter of pharynx begining @ sup. end & moving to inf. end, creates pressure diff. forcing swallowed material from pharynx into esophagus. E: bolus passes through esophagus & into stomach. presence of bolus w/in lumen of esophagus stimulatessequential peristaltic waves of muscular contraction that assist in propelling the bolus to stomach. higher pressure occurs in sup. region of esophagus relative to inf. region.Which stages are involuntary? pharyngeal & esophageal phaseWhere is the swallowing center located and what is its role? “deglutition center” in medulla oblongata;) stimulated by tactile sensory receptors that initiate nerve signals along sensory neurons then nerve signalsare relayed along motor neurons to effectors and cause the responses in pharyngeal phase - entry of bolus into oropharynx, elevation of soft palate & uvula to block passageway btwn orpharynx & nasopharynx, elevation of larynx by extrinsic muscles move larynx ant. & sup., resulting in epiglottis covering laryngeal opening (prevents ingested materials from entering trachea); nerve signals also relayed to resp. center to assure beath not taken during swallowing. What causes the inferior esophageal sphincter to relax and contract?
➢Clinical View: Reflux Esophagitis and GERDoDefine each of these and give causes. Reflux Esophagitis = acidic chyme refluxes into esophagus & causes burning pain & irritation; “heartburn”. Seen in overweight individuals,