Taste and Olfaction

Question 1

what are chemical senses?

Answer 1

special sensory systems that detect minute quantities of chemicals in the environment

Question 2

what do ‘tastant’ molecules interact with? odorant molecules?

Answer 2

structures called taste buds on tongue, palate, pharynx, epiglottis and esophogus

olfactory receptor neurons on the superior conchae

Question 3

what cranial nerves contribute to flavor?

Answer 3

CN I
CN V
CN VII
CN IX
CN X

Question 4

what cortex do the CNs send stimuli to in order to stimulate the idea of flavor?

Answer 4

orbitofrontal cortex

Question 5

what are the landmarks of the tongue?

Answer 5

sulcus terminalis which divides anterior from posterior

median sulcus which divides the tongue at the midline

Question 6

what are papillae?

Answer 6

sensory structure on the tongue that either contain taste buds or manipulate food

Question 7

what are the three important papillae?

Answer 7

filiform - contains no taste buds and important for food manipulation

fungiform- mushroom shaped and contain taste buds

circumvallate- concentrated near sulcus terminalis and contain many taste buds

Question 8

what three cells do taste buds contain?

Answer 8

• taste receptor cells
• sustentacular cells: provide nutrition and support
• basal stem cells: replace damaged TRCs

Question 9

what are glands of Von Ebner?

Answer 9

minor salivary glands that provide moisture and contain enzymes that help digest food

Question 10

from the anterior 2/3 of the tongue, taste fibers travel in which nerve?

Answer 10

lingual nerve that contains facial nerve fibers (CN VII) and trigeminal nerve fibers (CN V)

Question 11

from the posterior 1/3 of the tongue, taste fibers travel in what nerve?

Answer 11

glossopharyngeal nerve (CN IX)

Question 12

from the epiglottis, pharynx and palate, taste fibers travel in what nerve?

Answer 12

CN X

Question 13

which ganglion is associated with facial nerve (CN VII)?

Answer 13

geniculate ganglion

Question 14

which ganglion is associated with facial nerve (CN IX)?

Answer 14

petrosal ganglion

Question 15

which ganglion is associated with facial nerve (CN X)?

Answer 15

nodose ganglion

Question 16

where do the central processes of all primary taste afferents enter and terminate and what do they form?

Answer 16

medulla, nucleus of solitary tract
solitary tract

Question 17

axons of neurons in the nucleus of the solitary tracts ascend and project bilaterally where?

Answer 17

• ventral posteromedial nucleus of the THALAMUS
• then to the primary gustatory cortex via internal capsule

Question 18

what are the substructures of the primary gustatory cortex?

Answer 18

• anterior region contains insula
• frontal operculum in the inferior frontal gyrus

Question 19

where does the primary gustatory cortex project to inform flavor?

Answer 19

orbitofrontal cortex

Question 20

what is dysgeusia and what are the three types?

Answer 20

an alteration in taste

• hypogeusia: reduced sense of taste
• ageusia: inability to taste
• aliageusia: pleasant tastes start to taste unpleasant

Question 21

where do odorants enter and then contact?

Answer 21

• nasal cavity through the external nares and lodges
• contact dendrites of the olfactory receptor neurons of CN 1

Question 22

olfactory receptor neurons sit in a cell layer that contains?

Answer 22

supporting cells
basal stem cells
glands

Question 23

each olfactory receptor neuron (ORNs) has how many receptors?

Answer 23

ONE

Question 24

what do ORNs synapse with and where?

Answer 24

mitral cells in the olfactory bulb

Question 25

what is a glomerous?

Answer 25

a ball of mitral cell dendrites and axons of ORNs

Question 26

what are olfactory striae?

Answer 26

mitral cell axons that project out of the olfactory bulb and split into to tracts

Question 27

where do medial and lateral striae project?

Answer 27

medial: project to contralateral structures to aid in bilateral processing

lateral: project ipsilaterally to olfactory cortex located on the uncus of the temporal lobe