taste

what are the 5 “well accepted” tastes

• slaty

• bitter

• sour

• sweet

• umami

what are the two types of olfaction we experience in our sensory world

• orthonasal olfaction

• retronasal olfaction

what are the requirements for a basic taste

• has a defined class of effective stimuli

• has specialized transduction mechanisms

• the signal is conveyed by the gustatory system

what is gustation

taste

what structures play a part in flavor

• gustation

• retronasal

what are the taste receptors that recognize umami

T1R

what are the taste receptors that recognize salty

ENaC: epithelium sodium channels

what are the taste receptors that recognize bitter

T2Rs

what are the taste receptors that recognize sour

Otopetrin-1 (OTOP1)

what are the taste receptors that recognize sweet

T1R

where was OTOP1 first identified

in the vestibular system

what specifically is OTOP1

a proton-selective ion channel

what is included in the chemosensory perceptual systems

• gustation

• olfaction

• chemesthesis, including burning sensation

what CN caries chemosensation

trigeminal- V

if a receptor is not carried by the gustatory system…

it is NOT considered a basic taste

which cranial nerves are responsible for taste

7, 9, 10

where does CN VII carry taste from

the anterior 2/3 of tongue via chorda tympani and the palate- greater superficial petrosal branch of VII

where does CN IX carry taste from

the posterior 1/3 of the tongue

where does the CN X carry taste from

larynx

where is taste recognized on the tongue

• fungiform papillae on anterior 2/3

• foliate papillae in the folds in the rear/lateral

• circumvallate papillae in the rear that form a ‘V’

what papillae on the tongue do NOT recognize taste

filiform papillae

where does food dissolve to enter the taste bud

food will impinge on the taste receptor cells at the taste pore- only at the apical portion

what is the ratio of pores and taste buds per papillae

many pores and taste buds per papillae in humans; unlike rats- 1:1

what are the cell types found in taste buds

• type I

• type II

• type III

what innervates the anterior 2/3 of the tongue

chorda tympani and lingual nerve

lingual nerve has what type of nerve fibers

trigeminal- sensation for pain and touch

chorda tympani nerve has what type of nerve fibers

facial- taste, lingual cold and tactile

what does the chorda tympani specifically innervate

the taste receptor cells on the inside of the fungiform papilla

what type of nerve fibers does the glossopharyngeal nerve carry to the posterior 1/3 of the tongue

touch and pain information to the circumvallate papillae

what does the glossopharyngeal nerve specifically innervate

the para gammel area; outside the taste bud

why is this wrong

we do NOT perceive just one taste quality on each part of the tongue; taste buds from all regions of the oral cavity contain cells that respond to all five basic tastes

what is a type IV cells

is a progenitor cell for type I, II, and III

what is type I cell also known as

glial-like

what type of taste are type I cells responsible for

salty

what is type II cells also known as

receptor cell

what are type III cells also known as

presynaptic cell

which cell type is the only one where you see true vesical synapses w the nerve fibers

type III

which cell type has these features: round nucleus, come close to the nerve fiber to release ATP to stimulate nerve fibers and to communicate with type III cells

type II cells

what are the two major types of taste receptor proteins expressed by type II cells

contain G-protein coupled receptors for:

• T1Rs: involved in detection of sweet and umami

• T2Rs: involved in detection of bitter

for the sweet and umami receptors on type II cells, what does it need to have to function properly

need to have 2 functional units: heterodimer

what do type II cells release

ATP

what do type III cells release

serotonin

which cells type contains the otopetrin I receptor

type III

what do G-protein coupled receptors do in T1rs and T2rs

initiate a cascade of intracellular messaging system involving PLCbeta2, IP₃R3, and TrpM5

T2Rs are what type of receptor

transmembrane

T1Rs are what type of receptors

have a venus-flytrap domain- where sweetness is capture

what effect does the miraculous berry have on taste

makes sour things taste really sweet

MOA of miraculous berry

binds to sweet receptors during low pH levels (during reg pH, tastes blah)

what can drugs for treating cancer- like BCC cause

taste loss

what can progenitor cells in the basement membrane outside of the tastebuds differentiate into

• non-taste keratinocytes

• precursors for type I/II/III

what pathway will determine what the progenitor cells will become

the sonic hedgehog pathway

what will form based if the sonic hedgehog pathway is activated vs not activated

activated: form taste cells- type I/II/II

not activated: non-taste keratinocytes

what affect do BCC drugs have on the sonic hedgehog signaling pathway

one will act at SMO and others will act on the Shh binding PTCH → will block gene production → no formation of taste cells

how often do taste cells turnover

10-14 days

when can radiation cause permanent taste lost

when there is damage to the salivary glands (if no damage, taste can return)

how can dental injections cause taste loss

can be blunt nerve injury w the needle or some cytotoxicity from the the local anesthetic

what is the most common way to the lingual nerve is damaged → damaging taste

3rd molar extractions

what is happening on the tongue when you damage the lingual nerve

there is an atrophy of fungiform papillae

how can you cause taste loss during an ear surgery

chorda tympani travels along tympanic membrane of inner ear → can damage during surgery → will lose taste on the same side of damage ONLY

how can salivary issues cause taste loss

• saliva is necessary to dissolve food

• saliva protects taste cells from dehydration

• has growth factors necessary for the regeneration of the taste cells

how can viruses cause taste loss

• shingles in the facial nerve →loss of taste on affected side

• SARS-COV-2 → can directly enter cells via ACE2 receptors → directly will kill taste cells → can get complete taste loss

according to Sue how can you loose smell

whiplash → can shear axonos going through cribriform plate