CH. 8- Reflexes/ Responses
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reflexive response of infant to tactile stimulation of cheek or lips; causes infant to turn toward stimulus and open his or her mouth. infants rely on tactile stimulation of the perioral region.
reflex involving tongue protrusion and retraction in preparation for receipt of liquid; stimulated by contact to the upper lip(or inner margin of lips). infants rely on tactile stimulation of the perioral region. it involves generating a labial seal.
salivation: production and release of saliva into the oral cavity. it is not a sensory system, but rather a motor response. it is an essential component of taste, mastication, and deglutition. combination of saliva with different foods can create different tastes with possibility of making them more desirable.
they are associated with the systems of mastication and deglutition. expulsive reflexes refer to gag and retch reflexes.
a complex reflex that is triggered by deep pressure on the roof of the mouth. involves alternating left-side and right-side contraction of mandibular elevators (such that rotatory motion of mandible is produced). alternating contraction allows lingual musculature to move bolus on and off molars. chewing center is located within midbrain near III oculomotor and IV trochlear nerve nuclei.
Uvular (Palatal) Reflex
occurs in response to excitation of IX glossopharyngeal general visceral afferent(GVA) component bye irritation. mediated similar to gag reflex, involving palatal muscles innervated by X vagus.
Gag (pharyngeal) Reflex
elicited by (taste) and tactile stimulation of faucial pillars, posterior pharyngeal wall, or posterior tongue near lingual tonsils, which is mediated by IX glossopharyngeal nerve (GVA) component. dendrites convey sensation through inferior and superior ganglia of IX glossopharyngeal to solitary nucleus and solitary fasciculus of medulla oblongata in brainstem. connection with X vagus nerve via interneurons activates muscles of general visceral efferent(GVE) lineage.
Retch and Vomit Reflex
RETCHING is an involuntary attempt of vomiting. it is a complex response mediated by noxious smells (I olfactory), tastes (IX glossopharyngeal), gastrointestinal distress (X vagus), vestibular disfunction (VIII vestibulocochlear), or distressing visual or mental stimulation. VOMITING refers to oral expulsion of gastrointestinal contents. includes multiple simultaneous or synchronous reflexes(occlusion of airway, extreme abdominal contraction, etc).
is typically initiated by noxious stimulation of pharynx, larynx, or bronchial passageway. after GVA component of vagus nerve transmits info (of stimulation) to nucleus solitarius of medulla, interneurons activate expiration center of medullary reticular formation, causing abdominal muscles to contract. motor nucleus of X vagus permits subglottal pressure generated to dislodge substance.
Tongue Base Retraction and Elevation
retraction of tongue may be reflexively stimulated by pulling tongue forward. reflex is mediated by muscle spindle fibers within genioglossus. elevation of posterior tongue may be stimulated by pushing down on posterior, stretching palatoglossus, containing muscle spindles. both reflexive responses are intrinsic, localized responses of XII hypoglossal(for genio.), XI accessory, and X vagus(for palato.) nerves
can have effect on mastication and swallowing. the response represents a conscious version of withdrawal response, natural response to noxious stimuli. oral and pharyngeal pain responses include removal of noxious bolus, by expectoration/ swallowing.
occurs reflexively but can be voluntary controlled to degree. sensor system near carotid sinus responds to quantity of oxygen and CO2 in blood. when oxygen levels decline below a specific criterion level, or when CO2 or acidity increases beyond a specific level, signal mediated by IX glossopharyngeal via nucleus solitarious relays to respiratory center, incease resp. rate.
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