GI mouth and esophagus Flashcards
what are the functions of the alimentary canal?
ingestion, secretion, mixing and propulsion, digestion, absorption, defecation
gums
hold the teeth and cheek which necessary for mechanically grinding food down
upper and lower lips
close the oral cavity
frenulum (superior and inferior)
attaches lips to gums and prevents them from excessively moving away
hard palate
bony structure which is part of maxilla
soft palate
portion with muscles running through it and can be raised to close off nasopharynx
Uvula
helps close off nasopharynx, has huge density of irritant receptors to evoke gag reflex
tongue
constantly keep food up on the teeth so they can grind + mash it, involved in swallowing by pushing the bolus towards back of mouth
lingual frenulum
restricts movement of the tongue
what are the 5 primary tastes?
sweet, bitter, salty, sour, umami
vallate papillae
largest taste buds with 12 forming “V” at back of tongue each containing 100-300 taste buds
fungiform papillae
scattered over tongue each containing 5 taste buds
foliate papillae
in lateral margins of tongue; degenerate in childhood
filiform papillae
for tactile sensations and friction
gustatory receptor cells
sensory cells in the taste bud that transduce the chemical stimuli of gustation
what are the cranial nerves involved in gustation?
facial, glossopharyngeal, and vagus
facial nerve in gustation
anterior two thirds of tongue providing parasympathetic motor output to submandibular glands
glossopharyngeal nerve in gustation
posterior one third of tongue
vagus nerve in gustation
responsible for the throat and epiglottis
what is the trigeminal nerve’s role in gustation?
conveys tactile sensations for anterior two-thirds of tongue
gustatory pathway
sensations from cranial nerves to brainstem to thalamus to primary gustatory area
what does olfactory epithelium contain?
receptor cells, basal cells (neuronal stem cells), support cells
what do olfactory glands produce?
mucus
how does neural transduction of smell occur?
through odorant molecules that are dissolved in nasal mucus
insular cortex
where conscious perception of smell occurs (does not synapse in thalamus)
olfactory pathway
- molecules inhaled into nasal passages
- contact olfactory nerves in olfactory epithelium
- receptor cells activated
- signal is sent to olfactory bulb
- signals relayed to higher regions of brain via olfactory tract
what types of dentitions do humans have?
deciduous and permanent
how many incisors do adults have?
4 each on top and bottom; for cutting
how many canines do adults have?
2 each on top and bottom; for tearing
how many premolars do adults have?
4 each on top and bottom; for crushing
how many molars do adults have?
6 each on top and bottom; for grinding
enamel
hard, outermost layer of a tooth
dentin
dense tissue underneath enamel forming the bulk of a tooth
pulp
living portion within a tooth contain a neurovascular bundle
what nerve conveys tooth sensations?
CN V (trigeminal nerve); maxillary and mandibular branches
what does mastication require?
teeth tongue and cheek, saliva, muscles of mastication
what are the intrinsic tongue muscles?
longitudinal, transverse and vertical muscles
longitudinal muscles and how many sets?
2 sets (one on top, one on bottom) that shorten and retract the tongue
transverse muscles and how many sets?
2 sets of muscles causing the tongue to get skinnier
vertical muscles and how many sets?
1 set of muscles that help flatten the tongue when they contract (thinner)
what nerve innervates the intrinsic and extrinsic muscles of the tongue?
CN XII
what are the extrinsic muscles of the tongue?
styloglossus, hyoglossus and geniglossus; all of which attach the the base of the tongue at back of oral cavity
styloglossus
raises tongue at back of oral cavity to force bolus into pharynx
hyoglossus
depresses tongue into base of floor of mouth
genioglossus
allows you to stick tongue out (protrude)
what are the muscles of mastication?
temporalis and masseter; having an action on the mandible
what nerve innervates the muscles of mastication?
CN V - Trigeminal
temporalis
elevates mandible
masseter
“talking and chewing muscle”; attaches from maxilla all the way down to mandible
what are the muscles of facial expression?
buccinator and orbicularis oris; having an action on the cheek and mouth
buccinator
contributes to cheek movement; “chipmunk” cheeks or blowing up a balloon
orbicularis oris
circle around mouth acting like a sphincter; puckers lips, allow you to suck from straw, closes oral cavity
what nerve innervates the muscles of facial expression?
CN VII
vascular supply for mastication
mainly from external carotid arteries; facial, maxillary and superficial temporal artery - veins are named in a similar fashion
what are the major salivary glands?
parotid, submandibular, sublingual
what is the composition of saliva?
water, amylase, mucin, lysosome, IgA, defensins, electrolytes
parasympathetic saliva (CN VII and IX)
watery, enzyme-rich saliva
sympathetic saliva
thick, mucin-rich saliva
parotid gland saliva
serous w/ amylase
submandibular saliva
mostly serous w/ amylase
sublingual saliva
mostly mucous w/ lipase
stages of deglutition
voluntary, pharyngeal and esophageal
voluntary stage
oral cavity and tongue force bolus towards oropharynx
pharyngeal stage
deglutition reflex initiated by oropharynx stretch (initiates pattern generator), closing off of nasal cavity and trachea, relaxation of upper esophageal sphincter, soft palate + uvula rise to protect upper airway, raising of epiglottis and larynx to close tracheal opening
esophageal stage
involuntary passage through esophagus to stomach (peristalsis; proximal 1/3 skeletal and distal 1/3 smooth m.)
where are the 2 kinks in the esophagus located?
at the bifurcation of the trachea and in passing behind the left atrium
where is the esophageal hiatus?
in skeletal muscle of diaphragm
esophagus layers
mucosa, submucosa, muscularis and adventitia
mucosa
nonkeratinized stratified squamous epithelium, lamina propria, vascular and nerve supply
submucosa
CT gluing mucosa down to underlying layers
muscularis
2 layers; inner circular (sphincter-like contraction) and outer longitudinal (shorten tube length) to cause peristaltic wave
adventitia
adventitia
CT glued to surrounding structures to prevent movement
what is the function of the esophagus?
transport food from mouth to stomach
lower esophageal sphincter (LES)
relaxes in presence of bolus, mostly always closed due to HCl in stomach
hiatal hernia
protrusion of a part of the stomach upward through the opening in the diaphragm
GERD (gastroesophageal reflux disease)
heartburn presents as sub-sternal chest pain
what aggravates GERD?
smoking + alcohol (LES relaxation), coffee, chocolate, peppermint and stress (cortisol prod. increases HCl), obesity and pregnancy (anatomical alteration)
how can GERD be treated?
smaller meals, maintaining upright position after a meal, avoiding problematic foods and antacids
