1. No category

Tongue
In the buccal cavity of the
digestive system
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same layers as those of tubular
organs
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Mucosa, submucosa, and
muscularis
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muscularis = the muscularis
externa
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no muscularis mucosa
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Tongue
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ling = tongue
Mucosa: apical surface
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irregular; lingual papillae (pl.)
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Dorsal surface
singular: papilla
short projections-several types
lower surface
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smooth and straight
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Very slick
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Tongue
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Different types of papillae
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Filiform
Conical, numerous, no taste buds,
keratinized at tips
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•
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Increase friction for food manipulation
Fungiform
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Mushroom shaped- near tongue tip
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Poorly keratinized
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Between filiform
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Scattered taste buds on lateral surface
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Tongue
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Different types of papillae
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Foliate
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Poorly developed in humans
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two rows on dorsal-lateral surface
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lots of taste buds ~150
Circumvalate
7-12 in V-shaped region on posterior
dorsal
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Up to ~3mm diameter
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Non-keratinized
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Taste buds present~250
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make lingual lipase
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Tongue
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Epithelium
Mostly non-keratinized stratified
squamous epithelium
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Deals with potentially abrasive activities
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Lumenal surfaces of
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Buccal (oral) cavity
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Oropharynx
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Between mouth and throat
esophagus
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to the stomach.
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Tongue
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Epithelium of lower surface;
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Non-keratinized
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Flat basal surface
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No papillae
Upper surface of tongue
Parakeratinized (partial) on the
outer filiform papillae
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depending on mammal type
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Primates
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little papillar keratinization
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cats have a high degree
7
Wrong!
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Tongue
Taste buds (gustatory-receptor
sensory organs)
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Lateral epithelium of the fungiform and
circumvallate papillae.
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Taste buds
~5000- tongue
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~2500- soft palate
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~900- epiglottis
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~ 600- larynx, pharynx
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Span thickness of epithelium
Elongate and narrowing from the
widest point to pointed ends
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Made of two cell types:
1-Gustatory receptor cells
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2- Support cells
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Tongue
Gustatory receptor cells (taste
sensory cells)
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~20-40 per taste bud
A few microvilli
not distinguishable with the light
microscope; at distal end
microvilli membrane has molecule
receptor-sites
chemoreceptors
Generate impulses at the other end of
the cell
sent to the cerebrum
perception of a general flavor
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•
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Support cells (sustenticular cells)
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~20-40 per bud
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Tongue
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1-Gustatory cell
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light cytoplasm
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oval nucleus
2
2-supporting cell
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darker cytoplasm
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elongated nucleus
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1
3- Taste pore
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Opening to lumen
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4- Nerve fibers
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Hypogeusia
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4
Reduced sense of taste
Age, infections, meds, damage to
cranial nerve VII (facial)
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Tongue
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Lamina propria
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dense connective tissue
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Lower surface, thin
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Upper surface, thicker
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Interior of papillae
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Between adjacent papillae.
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Tongue
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Mucosal epithelium
ducts extend into the submucosa
and muscularis
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both upper and lower surfaces,
to mucus or seromucous glands
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Produce mucus for
protective coating
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No muscularis mucosa
14
Tongue
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Submucosa of the tongue
Submucosa not divided from
lamina propria;
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collagen; richly eosinophilic
contains small arteries and
small veins, etc.
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15
Tongue
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Muscularis
Mostly skeletal myofibers in
bundles
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oriented in 3 directions:
Allows the tongue to assume
a wide variety of shapes
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•
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Pattern is unique
Also present:
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mucus or seromucous glands,
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nerves
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blood vessels
sometimes adipose tissue,
etc.
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16
Soft palate
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Small organ
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posterior end of the mouth roof
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Mostly hard palate
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palatine bone
separates buccal from nasal
cavity
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soft palate
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no bone tissue
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projects posteriorly
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c. Soft palate
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Contains skeletal muscle tissue
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function; flex upward
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activities
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swallowing
block the passageway from
pharynx to nasal cavity
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Soft palate
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Mucosa; Oral (buccal) side
stratified squamous
epithelium
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ducts into submucosa and
muscularis
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to serous and mucous glands
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non-keratinized
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LP is very thin; dense CT
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no muscularis mucosae
19
Soft palate
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Nasal side
pseudostratified ciliated columnar
epithelium
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glandular; produce mucus
ducts into submucosa and
muscularis
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•
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to serous and mucous glands
LP same as buccal
20
Soft palate
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Submucosa
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Thin layer
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boundary with LP not defined
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less cellular LP
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small arteries, etc.
Ducts of serous and mucous
glands
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and sometimes glands
21
Soft palate
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Muscularis
mostly parallel skeletal muscle
tissue
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longitudinal
may be very difficult to
distinguish from the dense
CT of submucosa.
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22
Soft palate
Serous and mucous glands usually
present
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elongate, branched mucous acini.
usually intermingled with skeletal
muscle fibers.
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23
Salivary glands
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General characteristics
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Compound tubuloacinar exocrine glands
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produce digestive juices
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saliva ~750-1200 ml
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water, mucus, ions, antibodies
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pH 6.7-7.4
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solvent for taste, wetting agent
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Alpha-amlyase- carb digestion
Glands develop by extensions of lumenal
epithelium
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produce small branches that become
exocrine acini
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24
Salivary glands
Two kinds of glandular cells:
mucous and serous.
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Acini are sometimes either
purely one or other
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sometimes mixed acini;
form a "serous
demilune" (serous halfmoon) around clump of
mucous cells
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25
Salivary glands
Single layer of squamous-shaped
contractile myoepithelial cells
surround the acini
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impulses from nerve endings
trigger contraction
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squeezing the salivary juice into
the duct
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then oral cavity
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27
Salivary glands
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Tubuloacinar tissue divided into
lobes and lobules separated by CT
septa
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contain blood vessels and nerves
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thin layers of dense CT between acini
also capillaries, arterioles, venules,
smallest nerves, lymphatic vessels.
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Organ has a thin capsule of dense CT
28
Salivary glands
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Salivary glands differ on
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types of glandular cells
of acini
ratio of types of glandular cells
and acini
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abundance of small ducts
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Salivary glands
Submandibular gland or
submaxillary gland (sublingual)
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Sublingual; smallest; ~5% of saliva
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Serous cells = mucous cells
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three kinds of acini
mucous, serous and mixed
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serous acini are distorted by mucous
acini
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Small ducts abundant
moderately high viscosity of the
digestive juice
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d. Salivary glands
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Salivary glands
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Parotid gland
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Largest, floor of oral cavity
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~60% of saliva; branched tubuloacinar
Almost all serous cells; basal nuclei; granular
cytoplasm
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small ducts are scarce
Our example of parotid gland is an H&Epreparation thin-section with unusually light
staining
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not obvious that the glandular epithelial cells
are arranged in acini, and initially the
relatively scarce small ducts may not be
noticed
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consequently the section tends to be difficult
to recognize as being of parotid gland; there
is a strong tendency to misidentify it as liver.
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Salivary glands
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Parotid gland
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Epidemic parotiditis (mumps)
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acute viral infection by paramyxovirus
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transmitted by infected saliva
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Swollen and painful parotids
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Tissue infiltrated by plasma cells and macs
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