taste and olfaction anatomy Flashcards
where are olfactory receptors found
olfactory mucosa along the roof of the nasal cavity, inferior surface of cribiform plate, nasal septum and medial wall of superior turbinate
what kind of receptors are olfactory receptors
GPCRs
what happens after a ligand binds to an olfactory receptor
signals are sent to the olfactory bulb
what are basal cells
stem cells for olfactory receptors and supporting cells
what are brush cells
ciliated, columnar epithelial cells
what are olfactory fila and where do they terminate
bundles of olfactory receptor axons
terminate in olfactory bulb
what structure is made up of olfactory fila
CN I
what structures are found within the olfactory tract
- fibers of lateral olfactory tract
- cells of anterior olfactory nucleus
- fibers of anterior limb of anterior commissure
via what structure do centrifugal fibers of the olfactory tract enter to olfactory bulb
anterior commissure
are centrifugal fibers excitatory or inhibitory to granule cells
excitatory
what makes up the glomerular layer of the olfactory bulb
axons of olfactory receptor neurons synapsing on dendrites of mitral and tufted cells
what makes up the external plexiform layer of the olfactory glomeruli
tufted cells
dendrites of tufted cells, mitral cells and granule cells
dendrites of what cell type modulate tufted and mitral cell output
granule cells
what makes up the mitral cell layer of the olfactory glomeruli
large mitral cells, axons of tufted cells, granule cell processes and centrifugal fibers
what makes up the granular layer of the olfactory glomeruli
cell bodies of granule cells
axons of mitral and tufted cells
centrifugal afferents
what cells are the interneurons of the olfactory bulb
granule cells
does the olfactory bulb relay information to the thalamus
NO it projects directly to the the olfactory cortex
what six structures make up the olfactory cortex
- anterior olfactory nucleus
- olfactory tubercle
- piriform cortex
- anterior cortical amygdaloid nucleus
- periamygdaloid cortex
- lateral entorhinal cortex
what structure integrates olfactory, taste and other food-related cues
orbitofrontal cortex
to what structures does the olfactory cortex relay info
- insular cortex
- orbitofrontal cortex
- dorsomedial nucleus
what olfactory cortex structures relay info to the lateral hypothalamus
piriform cortex
anterior olfactory nucleus
what structure links olfactory input to learning and behavior
hippocampus
what symptom is associated with nasal polyps
hyposmia - decreased sensitivity to smell
what nerve innervates taste buds of the soft palate
greater superficial petrosal nerve (CNVII)
where are the cell bodies for taste (anterior 2/3) located
from what nerve do they arise
geniculate ganglion
CN VII
how is taste transduction initiated
soluble chemicals diffuse through taste pore => bind to receptors on apical microvilli of taste cell
what innervates the fungiform papillae and anterior foliate papillae
chorda tympani (branch of CN VII)
what innervates taste buds of the vallate papillae and posterior foliate papillae
lingual-tonsillar branch of CN IX
CN X innervates taste buds where and via what branch?
epiglottis and esophagus
superior laryngeal n
where are the cell bodies of the taste fibers from CN IX and X
petrosal and nodose (inferior) ganglia
what is the route of first-order taste fibers from the geniculate ganglion (CN VII)
enter brainstem at pontomedullary jxn via intermediate nerve => solitary tract => solitary nucleus => rostral gustatory nucleus
what is the route of first-order taste fibers from the inferior ganglia (CN IX and X)
enter medulla => descend in solitary tract => rostral gustatory nucleus
what is the route of second-order neurons of the taste fibers from the rostal gustatory nucleus
central tegmental tract => parvicellular ventral posteromedial nucleus (VPMpc)
what is the route of third-order neurons of the taste fibers from the VPMpc
posterior limb of internal capsule => inner frontal operculum and anterior insular cortex
what is ageusia and why is it rare
complete loss of taste
rare bc multiple nerves relay taste info
