Physiology of Mastication and Deglutition Part 2 Flashcards
Mastication and Deglutition Reflexes
-Mediated in brainstem
-Posterior brainstem: reticular formation
Chewing Center Reflexes
-Located in pons and caudal reticular formation
Chewing Center Reflexes Controls
-Mastication
-Tongue Movement: bolus generation and
move tongue on/off molars
-sucking
-licking
Sucking
-natural involuntary newborn reflex: initiate sucking when mouth or roof of mouth touched
-essential for feeding and developing coordination with breathing and swallowing
Rooting
-natural involuntary newborn reflex helps babies find and latch onto nipple to feed
-triggered by touching or stroking cheek or mouth
-producing head turn and open mouth: searching for food source
-perioral tactile stimulation mediated: V CN (Trigeminal)
Uvular (Palatal) Reflex
-Tactile sensors to uvula, fauces, or soft palate
-Cause velum to elevate
-Mediated: IX CN (glossopharyngeal)
Gag (Pharyngeal) Reflex
-Tactile stimulation of faucial pillars, posterior pharyngeal wall, or posterior tongue near lingual tonsils: can be elicited by taste
-Response: laryngeal elevation, vocal folds clamping, velum closes, abdominal muscles contract
-mediated: IX CN (glossopharyngeal)
Retch Reflex
-Involuntary attempt at vomiting
-can be caused by distressing visual or mental stimulation
-Retching center near swallow center in reticular formation
Retch Reflex Noxious Smells
-Noxious smells: CN I Olfactory
Retch Reflex Tastes
-Tastes: CN IX Glossopharyngeal
Retch Reflex GI Stress
-GI Stress: CN X Vagus
Retch Reflex Vestibular Dysfunction
-Vestibular Dysfunction: CN VII Vestibulocochlear
Vomit Reflex
-oral expulsion of GI contents
-includes multiple simultaneous and/or synchronous reflexes
Vomit Reflex Steps
-occlusion of airway: vocal folds adduct
-extreme contraction of abdominal walls
-relaxation of UES and LES
-Elevation of larynx and velum
-Depression of epiglottis
-Elevation of pharynx
-Tongue protrusion
Cough Reflex Initiated by
noxious stimulation of pharynx, larynx, or bronchial passageway
Cough Reflex CN X Vagus Nerve
CN X Vagus afferent transmits stimulation information to nucleus solitarius of medulla
Cough Reflex Interneurons
-Interneurons activate expiration center of reticular formation: causes abdominal muscles to contract
Cough Reflex Nucleus Ambiguous
-Nucleus ambiguous (motor nucleus of X CN [Vagus] causes laryngeal adduction prior to exhalation: produces subglottal pressure build up to dislodge irritant from airway
Gustation
-act or sensation of tasting
-fundamental sense helps identify and select foods
Basic Tastes Humans Can Perceive
-sweet
-salty
-sour
-bitter
-umami (savory)
Function of Gustation
-helps determine if something is nutritious, delicious, or potentially harmful
-allows us to choose what to eat or avoid
Gustation Mechanism
-mediated by taste buds located primarily on tongue
-contain specialized receptor cells detect different taste stimuli and transmit signals to brain
Gustation: Interaction w/other senses
-smell and trigeminal nerve stimulation
-registers texture, pain, temp
-create overall flavor experience
Gustation: Central Processing
-travels along cranial nerves to brainstem
-then thalamus
-finally gustatory cortex: taste processed and consciously perceived
Taste Buds or Cells
-Class of sensors called chemoreceptors: neural receptors respond to specific chemicals
-Located in epithelia of tongue within papillae
Taste Maps: Sweet, starchiness, umami
-anterior tongue
Taste Maps: Bitter
-posterior tongue
Taste Maps: Salty
-front sides of tongue
Taste Maps: Sour
-back sides of tongue
Taste Maps: Whole Tongue
-whole tongue perceives all tastes
-no taste map
Transmission of Tastes: CN VII (Facial)
-tongue anterior 2/3
-palate receptors
-sweet, salty, sour
Transmission of Tastes: CN XI (Glossopharyngeal)
-tongue posterior 1/3
Transmission of Tastes: CN X (Vagus)
-epiglottis and esophagus receptors
Transmission of Tastes: CN V (Trigeminal)
-chemistetics: detection of chemical stimuli by heat or pain
Aging Taste Changes
-intensity of taste and smell reduced: smell mostly
-causes loss of interest in food
-can add taste supplements: caution too much salt
-some medications give metallic taste or other unpleasant taste
Medications Effecting Taste
-tetracycline: antibiotic
-lithium carbonate: antipsychotic
-penicillamine: antiarthritic
-captopril: antihypertensive
Glandular Secretion: Parotid Glands
-posterior, under masseter
-secretes serous saliva (slippery)
-helps move bolus
Glandular Secretion: Sublingual Glands
-under anterior tongue
-secretes mucoidal (dense) saliva
-helps organize bolus
Glandular Secretion: Submandibular Glands
-secretes combo of serous and mucoidal saliva
Parotid Glands
-Innervated by CN IX (Glossopharyngeal)
-secretes serous saliva
-thin and slippery
-helps move bolus down pharynx
Sublingual Glands
-Innervated by CN VII (Facial)
-secrete mucoidal saliva
-thick
-binds bolus into unit
Submandibular Glands
-Innervated by CN VII (Facial)
-secretes combo mucoidal and serous saliva
