Meal Phases: Cephalic + Oral + Esophageal Flashcards
function of cephalic phase
prepare the GI tract for a meal
mechanism of cephalic phase
olfactory/visual/auditory cues trigger anticipatory cognitive pathways –> increase parasympathetic output to GI tract
effect of cephalic phase
- increased salivary, gastric, and pancreatic secretions
- relaxation of proximal stomach
function of oral phase
mechanical disruption and initiation of digestion (chewing and swallowing)
mechanism of oral phase
increase parasympathetic output to GI tract
effect of oral phase
- increased salivary, gastric, and pancreatic secretions
- relaxation of proximal stomach
- contraction of gallbladder to release bile into SI - triggered by CCK
chewing
- involves muscles of mastication, tongue, cheeks
- increases surface area of ingested solids
- mixes solids with saliva to lubricate bolus
what part of CNS controls swallowing
deglutition center in brainstem
is swallowing voluntary or involuntary
starts voluntary then becomes involuntary
voluntary part of swallowing
controlled by CNS only
- tongue pushes bolus back into pharynx
- sensory nerves detect bolus and activate deglutition center
involuntary part of swallowing
controlled by CNS and ENS
- closing of nasopharynx
- closing of oropharynx
- epiglottis blocks laryngeal opening
- wave of muscular contractions pushes bolus to esophagus
- UES relaxes to allow food into esophagus
function of esophageal phase
transferring food from mouth to stomach
prevention of reflux
mechanism of esophageal phase
bolus distends esophagus –> triggers mechanosensitive afferents (vagal and intrinsic) –> signals to vagal and intrinsic efferents –> motor reflex causes primary peristalsis of esophagus –> distention after primary peristalsis triggers secondary peristalsis –> secondary waves repeat until bolus is passed
effect of esophageal phase
bolus reaches the stomach
salivary glands
tubuloalveolar structures that contain acinar epithelial cells
