Module 3: Gustation

Question 1

which cranial nerve supplies the taste buds (epiglottis)

Answer 1

CNX

Question 2

which cranial nerve supplies the taste buds (posterior 1/3 of the tongue)

Answer 2

CN IX

Question 3

which cranial nerve supplies the taste buds (anterior 2/3 of the tongue)

Answer 3

CN VII

Question 4

where do the taste buds transmit information to

Answer 4

medulla nucleus of the solitary tract

Question 5

what brain structures does the medulla nucleus of the solitary tract have back-and-forth connections with

Answer 5

hypothalamus and amygdala

Question 6

what are the hypothalamus and amygdala involved in

Answer 6

pleasure, aversion, food seeking behavior, satiety

Question 7

where does the medulla nucleus of the solitary tract project to

Answer 7

VTM of thalamus

Question 8

where does the VTM of thalamus project to

Answer 8

insular and frontal taste cortices

Question 9

where does the insular and frontal taste cortices project to

Answer 9

amygdala

Question 10

what are the three subdivisions of papillae

Answer 10

fungiform (tip), foliate (sides), circumvallate (back, 8 - 10 count)

Question 11

what are the tastes

Answer 11

sweet, salty, sour, bitter, umami, fat

Question 12

what is CD36

Answer 12

a taste receptor localized to circumvallate and foliate papillae that binds to fatty acids

Question 13

how many taste buds does each papillae contain

Answer 13

1-100

Question 14

how many taste receptors does each taste bud contain

Answer 14

50-150 taste receptor
- also contain basal cells (stem cells that create receptors)

Question 15

type I cell function

Answer 15

support cell (glial-like function)

Question 16

type II cell function

Answer 16

detects sweet, umami, and bitter tastes

Question 17

type III cell function

Answer 17

detects sour, salt receptors

Question 18

what neurotransmitters do type II cells release

Answer 18

ATP

Question 19

what neurotransmitters do type III cells release

Answer 19

serotonin

Question 20

microvilli function

Answer 20

project to the taste pore where they are exposed to tastands

Question 21

where do taste receptors synapse

Answer 21

gustatory afferent axons

Question 22

which part of the tongue mostly senses sour

Answer 22

sides

Question 23

which part of the tongue mostly senses bitter

Answer 23

back

Question 24

which part of the tongue mostly senses salty and sweet

Answer 24

front and sides

Question 25

how does the insular cortex relate to taste

Answer 25

taste receptors make connections to insular cortex, and it has different areas for each type of taste

Question 26

which tastes do humans have an innate preference for

Answer 26

sweet, umami, and salt

Question 27

what is our threshold for detecting sour taste?

Answer 27

0.0009 M

Question 28

what is our threshold for detecting salty taste?

Answer 28

0.01 M

Question 29

what is our threshold for detecting sweet taste?

Answer 29

0.01 M

Question 30

what is our threshold for detecting bitter taste?

Answer 30

0.000008 M

Question 31

what does too much salt cause

Answer 31

high blood pressure, higher chance for cardiovascular diseases, heart attack, and stroke

Question 32

advantage of artificial sweeteners

Answer 32

less risk of obesity

Question 33

disadvantage of artificial sweeteners

Answer 33

weight gain, insulin resistance, T2 diabetes, cardiovascular disease, and mortality

Question 34

what is the overview of the salty pathway

Answer 34

Na+ ions enter through amiloride-sensitive Na+ channesl

Question 35

what is the overview of the sour pathway

Answer 35

H+ enters through H+ - sensitive TRP-channel (polycystic kidney disease (PKD) variant))

Question 36

what is the overview of the sweet pathway

Answer 36

heterodimer consisting of G-protein-coupled receptors T1R2 & T1R3

Question 37

what is the overview of the umami pathway

Answer 37

T1R1 & T1R3 GPCR & TRPM5 channel (Ca2+ goes through)

Question 38

what is the overview of the bitter pathway

Answer 38

T2R (gustuducin) --> alpha -->IP3 --> TRPM5 channel w/ Ca2+

Question 39

how many taste receptors are able to detect bitter substances

Answer 39

30 taste receptors

Question 40

what does higher concentration of intracellular Ca2+ cause in a type II taste cell

Answer 40

increases activity of TRPM5 channels

Question 41

what does increased activity of TRPM5 channels do

Answer 41

increases influx of Na+, depolarizing the cell

Question 42

what results from Calhm1 and P2X receptor knockout in mice

Answer 42

loss of perception of sweet, umami, and bitter compounds

Question 43

what is STIM1

Answer 43

endoplasmic reticulum Ca2+ sensor

Question 44

what is Plc

Answer 44

phospholipase C

Question 45

what does Ca2+ do under resting conditions in Type II taste cells

Answer 45

is stored in ER; STIM1 bond with Ca & uniformly distributed within ER membrane

Question 46

what happens when Ca store is depleted

Answer 46

Ca2+ unbinds STIM1 and triggers its oligomerization and migration ==> ER membrane junctions; activation of store-operated Ca channels (SOC)

Question 47

what are the receptor proteins for sweet

Answer 47

T1R2, T1R3

Question 48

what are the receptor proteins for umami

Answer 48

T1R1, T1R3

Question 49

what are the receptor proteins for bitter

Answer 49

T2Rs

Question 50

what does KO of T1R2 do

Answer 50

loss of ability to taste sweet

Question 51

what does KO of T1R1 do

Answer 51

loss of umami taste

Question 52

what does KO of T1R3 do

Answer 52

loss of sweet and umami taste

Question 53

which cells is T2Rs expressed in

Answer 53

cells that don't express sweet/umami receptors

Question 54

what is TRPM5 involved in

Answer 54

taste of sweet and umami

Question 55

what does KO of TRPM5 result in

Answer 55

mice don't avoid water with quinine

Question 56

what kind of signal processing does the brain have for taste

Answer 56

labeled line coding

Question 57

can one receptor be activated by more than one tastant?

Answer 57

yes in real life, but we will assume that only one receptor can be activated by 1 tastant

Question 58

where are taste signals sent

Answer 58

gustatory axons

Question 59

where do gustatory axons project

Answer 59

brainstem

Question 60

where does brainstem project

Answer 60

thalamus

Question 61

where does thalamus project

Answer 61

cerebral cortex

Question 62

what is flavor

Answer 62

overall sensation (taste, touch, pain, and smell)