taste and olfaction anatomy

Question 1

where are olfactory receptors found

Answer 1

olfactory mucosa along the roof of the nasal cavity, inferior surface of cribiform plate, nasal septum and medial wall of superior turbinate

Question 2

what kind of receptors are olfactory receptors

Answer 2

GPCRs

Question 3

what happens after a ligand binds to an olfactory receptor

Answer 3

signals are sent to the olfactory bulb

Question 4

what are basal cells

Answer 4

stem cells for olfactory receptors and supporting cells

Question 5

what are brush cells

Answer 5

ciliated, columnar epithelial cells

Question 6

what are olfactory fila and where do they terminate

Answer 6

bundles of olfactory receptor axons

terminate in olfactory bulb

Question 7

what structure is made up of olfactory fila

Answer 7

CN I

Question 8

what structures are found within the olfactory tract

Answer 8

• fibers of lateral olfactory tract
• cells of anterior olfactory nucleus
• fibers of anterior limb of anterior commissure

Question 9

via what structure do centrifugal fibers of the olfactory tract enter to olfactory bulb

Answer 9

anterior commissure

Question 10

are centrifugal fibers excitatory or inhibitory to granule cells

Answer 10

excitatory

Question 11

what makes up the glomerular layer of the olfactory bulb

Answer 11

axons of olfactory receptor neurons synapsing on dendrites of mitral and tufted cells

Question 12

what makes up the external plexiform layer of the olfactory glomeruli

Answer 12

tufted cells

dendrites of tufted cells, mitral cells and granule cells

Question 13

dendrites of what cell type modulate tufted and mitral cell output

Answer 13

granule cells

Question 14

what makes up the mitral cell layer of the olfactory glomeruli

Answer 14

large mitral cells, axons of tufted cells, granule cell processes and centrifugal fibers

Question 15

what makes up the granular layer of the olfactory glomeruli

Answer 15

cell bodies of granule cells
axons of mitral and tufted cells
centrifugal afferents

Question 16

what cells are the interneurons of the olfactory bulb

Answer 16

granule cells

Question 17

does the olfactory bulb relay information to the thalamus

Answer 17

NO it projects directly to the the olfactory cortex

Question 18

what six structures make up the olfactory cortex

Answer 18

• anterior olfactory nucleus
• olfactory tubercle
• piriform cortex
• anterior cortical amygdaloid nucleus
• periamygdaloid cortex
• lateral entorhinal cortex

Question 19

what structure integrates olfactory, taste and other food-related cues

Answer 19

orbitofrontal cortex

Question 20

to what structures does the olfactory cortex relay info

Answer 20

• insular cortex
• orbitofrontal cortex
• dorsomedial nucleus

Question 21

what olfactory cortex structures relay info to the lateral hypothalamus

Answer 21

piriform cortex

anterior olfactory nucleus

Question 22

what structure links olfactory input to learning and behavior

Answer 22

hippocampus

Question 23

what symptom is associated with nasal polyps

Answer 23

hyposmia - decreased sensitivity to smell

Question 24

what nerve innervates taste buds of the soft palate

Answer 24

greater superficial petrosal nerve (CNVII)

Question 25

where are the cell bodies for taste (anterior 2/3) located

from what nerve do they arise

Answer 25

geniculate ganglion

CN VII

Question 26

how is taste transduction initiated

Answer 26

soluble chemicals diffuse through taste pore => bind to receptors on apical microvilli of taste cell

Question 27

what innervates the fungiform papillae and anterior foliate papillae

Answer 27

chorda tympani (branch of CN VII)

Question 28

what innervates taste buds of the vallate papillae and posterior foliate papillae

Answer 28

lingual-tonsillar branch of CN IX

Question 29

CN X innervates taste buds where and via what branch?

Answer 29

epiglottis and esophagus

superior laryngeal n

Question 30

where are the cell bodies of the taste fibers from CN IX and X

Answer 30

petrosal and nodose (inferior) ganglia

Question 31

what is the route of first-order taste fibers from the geniculate ganglion (CN VII)

Answer 31

enter brainstem at pontomedullary jxn via intermediate nerve => solitary tract => solitary nucleus => rostral gustatory nucleus

Question 32

what is the route of first-order taste fibers from the inferior ganglia (CN IX and X)

Answer 32

enter medulla => descend in solitary tract => rostral gustatory nucleus

Question 33

what is the route of second-order neurons of the taste fibers from the rostal gustatory nucleus

Answer 33

central tegmental tract => parvicellular ventral posteromedial nucleus (VPMpc)

Question 34

what is the route of third-order neurons of the taste fibers from the VPMpc

Answer 34

posterior limb of internal capsule => inner frontal operculum and anterior insular cortex

Question 35

what is ageusia and why is it rare

Answer 35

complete loss of taste

rare bc multiple nerves relay taste info