Gustatory and Olfactory System Histology Flashcards
In what directions is the skeletal muscle of the tongue organized
longitudinal, transverse, and oblique
What portion of the tongue consists of a core mass of skeletal muscle oriented in three directions
anterior 2/3
The posterior 1/3 of the tongue displays what
aggregates of lymphatic tissue, the lingual tonsils
The tongue is developed from which branchial arches
1-4
The anterior 2/3 of the tongue comes from which branchial arches. What are their innervation
1st and 2nd
trigeminal (1) and facial (2)
The posterior 1/3 of the tongue comes from what branchial arches? What are their innervation
3rd and 4th
glossopharyngeal
vagus
Dorsal surface of the tongue is covered by what kind of epithelium
non keritinized stratified squamous epithelium (supported by a lamina propria, associates with the muscle core of the tongue)
what kind of papillae are located in front ot the v shaped sulcus terminalis, what are they associated with
circumvalate papillae, ebners glands
What are the four pairs of intrinsic muscles in the tongue
superior longitudinal
inferior longitudinal
transversus linguae
verticalis linguae
Serous and mucous glands extend across the ________ and the _____
lamina propria and the muscle
What is the purpose of the serous and mucous glands
suspend tastants so they can be taken and delivered to taste buds
where do the ducts of serous and mucous glands open
into the crypts and furrows of the lingual tonsils and circumvallate papillae
What forms a lingual papilla
a core of CT, and an epithelial layer on top (stratified squamous epithelium)
the CT is highly vascular
What are the four types of lingual papillae?
filiform
fungiform
circumvallate
foliate
What are the three types of papillae that contain taste buds?
fungiform
circumvallate
foliate
Describe the type of lingual papilla that doesn’t contain taste buds
filliform - have barbs that grab ahold of food. Dogs and cats have a lot of these
Describe geographic tongue
oral manifestation of psoriasis
dermatological condition which causes patches of dry, flaky, itchy skin
classic manifestation= area of erythema, with atrophy of filiform papille of tong, surrounded by serpiginous white, hyperkaratotic border
What type of epithelium are found on fungiform papillae? where are their taste buds located?
non keritinized stratified squamous
taste buds along apical surface
What types of lingual papillae are the serous glands (Ebner’s) associated with
circumvallate and foliate.
What layers of the tongue are ebner’s glands found in
in the CT, in contact with the underlying muscle
What do the ebner’s glands secrete (2)
lingual lipase and VEGP
What does Von Ebner’s Gland Protein (VEGP) do
undertakes selective binding of sapid (flavorful) chemicals and their transport to taste receptors.
What type of epithelium are associated with foliate papillae? What structures are associated with them?
Stratified squamous epithelium
Von Ebner’s glands (Serous glands)
How are foliate papillae arranged? where are their taste buds located
parallel rows
taste buds in lateral walls.
What part of the tongue are circumvallate papillae located
posterior part, aligned in front of the sulcus terminalis
Describe the circumvallate papillae
circumvallate= wall-like
occupy a recess in the mucosa, and therefore are surrounded by a circular furrow or trench
What is the benefit of the trench surrounding a circumvallate papilla
can suspend fluid in it and localized tastant particles in that trench. difficult for them to get out, easier for taste buds to access
Where are the taste buds located in circumvallate papillae?
sides of the papillae and the facing wall of the furrow
How many cells are there in a taste bud
50- 150, with the narrow, apical end of the taste bud extending into a taste pore
What are the three components of each taste bud
taste receptor cells
supporting cells
precursor cells
Where are the ovoid chemoreceptors found in the tongue
papillae
soft palate
posterior pharynx
epiglotis
life span of taste receptor cells
10-14 days
Describe the life cycle of taste receptor cells
precursor cells give rise to supporting cells (immature taste cells) which in turn become mature taste receptor cells.
How to taste receptor cells communicate with the cranial nerves
basal portion of taste receptor cell makes contact with an afferent nerve terminal derived from neurons in the sensory ganglia of the facial, glossopharyngeal and vagus nerves
(each taste receptor cell has its own afferent nerve fiber coming out of it)
Mechanism of taste
tastant binds taste receptor
GPCR, causes the cell to either depolarize or hyperpolarize
a change in intracellular Ca2+ triggers the release of NTs at the afferent synapse with the afferent nerve terminal
AP goes back to brain through cranial nerves to be analyzed
Nerve fibers innervate which cells in taste buds
all three
basal cells, supporting cells, receptor cells
What are the 5 taste sensations
sweet, salty, sour, bitter, umami
Facial nerve carries what sensations
all 5
glossopharyngeal carries what taste sensations
sweet and bitter
Nontaster, normal and super taster is based on density of what
fungiform papillae
Sweet stimuli is sensed where
what type of compounds
tip of tongue (sugars)
Salty stimuli is tasted where
what type of compounds
posterior and lateral to tip of tongue
sodium
Sour is tasted where
what type of compounds
on anterior 2/3 of dorsum and along the lateral margin
acidic, H+
Bitter tastants are what kind of compounds
varied compounds with no common molecular structure
caffeine, morphine, nicotine
Is there a genetic component to taste?
yes - some people more sensitive to bitter (kohlrabi test)
Umami is linked to a specialized receptor for what
L glutamate and other amino acids.
Umami is associated with
meats, cheeses, some vegies, glutamate signals presence of proteins and causes intake of proteinious foods.
added to processed foods as MSG, which is a flavor enhancer
taste buds on the palate register primarily (2)
bitter and sour
Posterior pharynx and epiglottis register which modalities
all 5
CD36
Protein receptor that specifucally responds to the flavor of fat
functions to facilitate the uptake of fatty acids
may also increase preference for fatty foods.
Sensory innervation to the anterior 2/3 of tongue
lingual nerve (trigeminal)
innervation of taste buds to anterior 2/3 of tongue (SVA)
facial nerve
Origin of ant 2/3 of tongue
median tongue bud, lateral lingual swellings
Origin of posterior 1/3 of tongue
hypopharyngeal eminence
Sensory innervation to posterior 1/3 of tongue
glossopharyngeal nerve
innervation of taste buds (SVA) to posterior 1/3 of tongue
glossopharyngeal
vagus
Type of epithelium that lines the nasal cavity
pseudostratified columnar epithelium with goblet cells
The lamina propria of the nasal cavity contains both _______ and _______ ______ and their function is to
The lamina propria also contains extensive ______ or _____ for _______
serous and mucous glands
moisten inspired air and trap particulate contaminants
vascular plexus swell/cavernous bodies for temperature control
what are the immune cells present in the nasal cavity
mast cells plasma cells (IgA, IgE, IgG)
Three functions of the nasal mucosa
air hydration
air filtration
temperature regulation
Air hydration
secretions of serous and mucous glands and goblet cells moisten the surface of the nasal cavity
add water vapor to inspired air
Air filtration
chonchae interrupt air flow and create turbulance
particulate matter thrown against chonchae and adheres to its moist surface
cilia move mucus/matter into nasopharynx
Temperature regulation
superficial vascular plexus (swell bodies) within lamina propria
can warm or cool inspired air
Where is olfactory epithelium found. what type of epithelium is it?
restricted to roof of nasal cavity-upper surface of superior conchae
pseudostratified columnar epithelium with three types of cells.
underlying lamina propria also contains lymphoid cells
What are the three types of cells in olfactory epithelium?
olfactory cells
supporting (sustentacular cells)
basal cells
Describe olfactory cells
bipolar sensory neurons, span the thickness of the epithelium
dendrite extends to surface and dilates to form olfactory vesicle
projects, along with cilia, above epithelial surface
proximal surface extends basally, becomes a non- myelinated axon and forms bundles of nerve fibers - the fila olfactoria (goes up through cribiform plate)
Describe the supporting cells (olfactory)
=sustentacular cells
columnar cells with oval nuclei
apical surface has microvilli submerged in seromucous fluid layer
light yellow pigment
PROIDE PHYSICAL SUPPORT, NOURISHMENT AND ELECTRICAL INSULATION (TIGHT JUNCTIONS AROUND THEM) FOR OLFACTORY CELLS.
Describe the basal cells (olfactory)
mitotically avtive stem cells
produce daughter cells that first differentiate into immature olfactory cells and thn mature olfactory cells
Do olfactory cells proliferate during adult life
yes
what is the lifespan of an olfactory cell
30-60 days
Cilia contain the ________. there are ~1000 genes expressing these, but each olfactory cell expresses only one ____ gene
olfactory receptor
OR
Olfactory serous glands (aka______) secrete a serous fluid in which_____
glands of BOwman
odoriferous substances are dissolved
The secretory fluid of the olfactory serous glands contains_____ with high binding affinity for a large number of odorant molecules . what is its purpose
odorant-binding protein OBP
OBP carries odorants to receptors present on the surface of the modified cilia and remeoves them after they have been sensed
The secretory product of the glands of bowman contains protective substances such as
lysozyme and IgA secreted by plasma cells.
Olfactory nerve filaments are bundled in groups of 10-100 and penetrate the ______ of the _____bone. reaching the ___________.
Here, the axon terminals connect with synaptic terminals of _____ cells, forming synaptic structures called _______.
cribiform plate ethmoid bone olfactory bulb mitral cells glomeruli
The olfactory signal is sent by _______ cells through the olfactory nerve tract to the __________ of the brain
mitral
corticomedial amygdala portion
temporary or permanant eamage to the olfactory epithelium causes
anosmia (loss of sense of smell)
axons from olfactory cells with the same odorant receptor terminate in 1-3 ______ present in the olfactory bulb
glomeruli
dendritic endings of predominantly mitral cells extend into the _______. Axons of mitral cells form the ________.
glomeruli
olfactory tract
lifespan of olfactory receptor cells is ______. can regenerate from _____-
30-60 days
basal cells.
Physical characteristics of Kallman syndrome
anosmia, small genitalia and sterile glands
What is responsible for the anosmia in Kallman syndrome
lack of neurons in the brain (mitral cells) that receive input from olfactory nerurons (olfactory bulb does not develop)
what is responsible for the small genitalia/sterility in Kallman syndrome?
lack of GnRH secreted by hypothalamus
GnRH required of secretion of LH, which is required for development of gonads and genital maturation
GnRH secreting neurons originate where
NOT in the hypothalamus
originate in olfactory epithelium (vomeronasal organ) and migrate into the brain
What is the mechanism of Kallman syndrome
failure of GnRH secreting neurons and olfactory neuron growth cones to migrate into the brain
(axons of olfactory neurons must contact developing brain to stimulate olfactory bulb development)
If they dont migrate, you dont get GnRH secreting neurons or mitral cells
Genetic defect that causes Kallman syndrome
KAL-1 is the defective gene
codes for anosmin 1, a cell adhesion protein that is expressed in the olfactory system and the medial walls of primitive cerebral hemispheres.
