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Physiology > Taste and Smell > Flashcards

Taste and Smell Flashcards

1
Q

— — are the peripheral organs of gustation

A

Taste Papillae

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2
Q

Papillae contain — —, the functional units of gustation

A

Taste Buds

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3
Q

Adults have — taste buds. Children
have —. After — years, many taste buds
degenerate.

A

3,000-10,000
more
45

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4
Q

Taste Buds contain

A

Taste Receptor Cells

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5
Q 
Taste Receptor Cells 
are --- Cells, not 
neurons.  Receptors are 
on ---.  VERY high 
--- rate.
A

Epithelial
cilia
turnover

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6
Q

Taste Buds contain Taste Receptor Cells, including (3)

A

taste receptor cells
supporting cells
basal cells

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7
Q

Location of Taste Papillae (6)

A 
Tongue, 
Hard & Soft Palate, 
Pharynx, 
Epiglottis, 
Larynx
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8
Q

1000s of tastes are differentiated primarily based on the

activation of – different receptors.

A

5

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9
Q

All tastants must dissolve in —

A

saliva

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10
Q

Individual taste receptor cells may be sensitive to
a specific taste stimulus, but many taste receptor
cells have receptors for

A

multiple taste types

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11
Q

— is vital for normal gustation.

A

Olfaction

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12
Q

(3) tastes are accounted for
by two families of taste receptor genes– TR1 &
TR2, both of which utilize the G protein gustducin.

A

Sweet, bitter, and umami

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13
Q

(2) are detected by ion channel linked

receptors.

A

Sour and salty

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14
Q

Sour Taste is stimulated by

A

H+, Protective taste (blocks K+ exit, increase in IC K+, depolarization)

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15
Q

Sour taste:

Multiple candidate receptors (2)

A

a. Amiloride-sensitive epithelial Na+ channel
(ENaC), H+ channels, blockade of K+ channels.
b. All potential mechanisms lead to depolarization
of receptor cells

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16
Q

Sour Taste:

strongly linked to (2)

A

salvation and contraction of facial muscles

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17
Q

Sweet taste:

Lots of stimuli: (7)

A 
sugars, 
glycols,                        
alcohols, 
artificial sweeteners                     
(saccharine, aspartame, sucralose)
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18
Q

Sweet taste:
T1R receptor family is important.
Specifically, T1R2 & T1R3 proteins make
a dimer that is — linked

A

G-protein

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19
Q 
T1R receptor family is important.   
Specifically, T1R2 & T1R3 proteins make 
a dimer that is G-protein linked
i. Broadly sensitive to sweet-tasting 
substances.  
ii. Sweet receptors are usually NOT on the 
same cells as
A

bitter & umami.

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20
Q

Bitter Taste:

Stimuli are usually organic: (8)

A 
K+,       
denatonium, 
caffeine, 
strychnine, 
quinine, 
nicotine, 
broccoli, 
brussel sprouts
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21
Q

Bitter taste:

Protective taste:

A

highest number of
receptors and lowest threshold for
perception

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22
Q 
Bitter taste:
Multiple Receptors (50-80) in --- family
A

T2R (G PROTIEN)

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23
Q

Denatonium salts are colorless
and odorless solids that are
used to prevent

A

inappropriate
ingestion (denatured alcohol,
antifreeze, nail biting
preventions, liquid soaps, etc.).

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24
Q

Salty:

Stimulated mostly by – and somewhat by –

A

Na+

Cl-

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25
Q

Salty:
Receptor: (2)

A

i. ENaC (Na+ channel)

ii. Cl- via paracellular transport?

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26
Q

Umami:
Stimulus:

A

monosodium glutamate, enhanced by

ribonucleotides

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27
Q

Umami:
Receptor:

A

i. Metabotropic glutamate receptor (mGLuR4 receptor)

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28
Q

Taste threshold refers to

A

the minimum
concentration at which a substance can be
perceived

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29
Q

The threshold concentrations of
substances to which the taste buds respond
vary with the

A

particular substance

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30
Q

— substances tend to have the lowest

threshold

A

Bitter

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31
Q

Some toxic substances such as
strychnine have a bitter taste at very low
concentrations, preventing

A

accidental
ingestion of this chemical, which causes fatal
convulsions

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32
Q

substance: HCl
taste:
threshold:

A

taste: sour
threshold: 100 umol/L

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33
Q

substance: NaCl
taste:
threshold:

A

taste: salt
threshold: 2000 umol/L

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34
Q

substance: Strychine HCl
taste:
threshold:

A

taste: bitter
threshold: 1.6 umol/L

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35
Q

substance: glucose
taste:
threshold:

A

taste: sweet
threshold: 80,000 umol/L

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36
Q

substance: sucrose
taste:
threshold:

A

taste: sweet
threshold: 10,000 umol/L

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37
Q

substance: Saccharin
taste:
threshold:

A

taste: sweet
threshold: 23 umol/L

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38
Q

taste receptors are also found in the (5)

A 
stomach, 
bile duct, 
intestines, 
bronchi, & 
kidneys
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39
Q

Despite the similarities in receptor molecules and signaling
cascades, however, only the chemoreceptive systems in the mouth
evoke a sensation of taste. The others, researchers are learning,
serve different functions depending on their —

A

location

40
Q

Perhaps protective in the airways—stimulating

A

sneezing,

respiratory escalator

41
Q

In the gut (3)
– Sweet receptors may be involved in..
– Bitter receptors in stomach stimulate…
– Bitter receptors in colon induce…

A

insulin stimulation
CCK (satiety) & emesis
osmotic gradient which leads to diarrhea

42
Q

Taste Specificity is best at — ligand concentrations

A

low

43
Q

Taste does not solely depend on combinations of the aforementioned 5 receptors, also (3)

A

a. Smell
b. Fat, electric, metallic, pain, temperature
c. Taste modifiers

44
Q

Taste Adaptation (2)

A

a. Only about 50% occurs at the receptor

b. Threshold for sensitivity can change

45
Q

Taste Preference (2)

A

Genetic, cultural influences.

46
Q

Taste Perception (5)

A
  1. Taste Specificity is best at low ligand concentrations
  2. Taste does not solely depend on combinations of the aforementioned 5 receptors
  3. Taste Aversion
  4. Taste Adaptation
  5. Taste Preference
47
Q

Are you a Non-Taster,
Medium Taster,
or Supertaster?
• Differences once thought to be solely dependent on

A

genes for bitter taste receptor

48
Q

Supertasters (2)

A

have more taste buds and more afferent gustatory neurons.

Are also more responsive to other tastant types.

49
Q

Nontasters tend to have higher

A

body weights

– There may also be a link to fat perception

50
Q

Taste Receptor cells synapse on

A

first order neurons

51
Q

Taste Receptor cells synapse

on first order neurons (2)

A

a. Redundant, bilateral
innervation
b. Neurons enter the CNS via
Cranial Nerves VII, IX, or X

52
Q

Facial Nerve (CN VII) (2)

A

•Chorda Tympani Branch—anterior
2/3 of the tongue
•Greater petrosal superficial nerve—
papillae on soft palate

53
Q

Glossopharyngeal (CN IX) -

A

posterior 1/3

of the tongue

54
Q

Vagus Nerve (CN X) - (3)

A

pharynx, epiglottis,

larynx

55
Q

Second Order Neurons Cell

bodies in the

A 
gustatory 
division of the nucleus of the 
solitary tract (in the medulla 
(nucleus tractus solitarii, 
NTS)
56
Q

The NTS is a purely sensory
nucleus in the medulla and it
receives input for (3)

A

taste,
chemoreceptors, aortic
bodies, etc.

57
Q

Third Order Neurons Cell

bodies in the

A

ventral
posteromedial nucleus of
the thalamus

58
Q

Humans are able to differentiate
10000 odors with a relatively
poorly developed olfactory
epithelium of only

A

10-40 million

receptor cells

59
Q

Free endings of many trigeminal pain fibers are found in the olfactory epithelium.
They are stimulated by

A

irritating substances

60
Q

Free endings of many trigeminal pain fibers are found in the olfactory epithelium.
They are stimulated by irritating substances, which leads to the characteristic “odor” of such substances as (3)

A

peppermint, menthol, and chlorine

61
Q

Activation of these endings by nasal irritants also initiates (4)

A

sneezing, lacrimation, respiratory inhibition, and other reflexes

62
Q

Anatomy of Olfactory Membrane (5)

A
  1. In superior & posterior portions of each nostril
  2. Olfactory Cells are primary
    afferent neurons
  3. Sustentacular/Supporting Cells
  4. Basal Cells
  5. Bowman’s Glands
63
Q 
Receptor cells are --- neurons 
that have a short peripheral 
process that extends into the 
mucosa where it ends in an 
expended olfactory knob
A

bipolar

64
Q

The knob gives rise to several — that form a
dense mat at the mucosal surface.
The cilia interact with — in
mucus.

A

cilia

odorants

65
Q

New receptor cells generated every – days from basal cells and they
must form synapses with

A

60

mitral cells in the olfactory bulb

66
Q

Axons of the Olfactory Receptor Cells pass through the

Cribriform Plate of the Ethmoid bone to synapse with

A

Mitral

Cells in the Olfactory Bulb.

67
Q

Glomeruli

A 
globular 
structures in the 
olfactory bulbs and it is 
where the short axons 
from olfactory receptor 
cells terminate. Each 
glomeruli is the 
terminus for ~25,000 
axons and dendrites 
from mitral cells.
68
Q

RMP of olfactory receptor cell is — mV so the receptor cells will generate continuous APs (1 every 20 seconds to 2-3 per second).

A

-55

69
Q

Odorants cause depolarization to — mV, which causes an increase in AP frequency (20-30 per second)

A

-30

70
Q

The rate of AP signals varies in proportion to logarithm of

A

stimulus

strength

71
Q

olfactory
receptor cells with one
type of odorant receptor
project to

A

one olfactory

glomerulus (OG)

72
Q

olfactory receptor cells
with another type of
receptor project to a

A

different OG

73
Q

There are > — functional olfactory
genes in humans and multiple types of
olfactory receptors

A

500

74
Q

G-protein coupled receptors (Golf),

coupled to

A

adenylyl cyclase

75
Q

Increased levels of cAMP open sodium channels to

A

depolarize the
olfactory neuron

76
Q

Other receptors may act via other

A

2nd
messengers

77
Q

To be perceived, odorants must (4)

A

a. Be volatile (spread in air—small)
b. Be partially water-soluble
c. Be partially lipid-soluble
d. Reach olfactory mucosa (normal breath vs.
sniff

78
Q

Adaptation
a. –% of adaptation is achieved in the first
second
b. Further receptor adaptation is (2)

A

50

limited and slow

79
Q

A postulated neuronal mechanism for adaptation. “Large numbers of centrifugal nerve fibers pass from the olfactory regions of the brain backward along the olfactory tract and terminate on

A

special inhibitory cells in the olfactory bulb, the

granule cells

80
Q

it has been postulated that after the onset of an olfactory stimulus,
the CNS quickly develops

A

strong feedback inhibition to suppress relay of the smell signals through the olfactory bulb

81
Q

Termination of Smell Perception: (3)

A

Odorants must diffuse

away, be broken down by enzymes, or adaptation occurs

82
Q

Coding of Olfaction (3)

A

a. Olfactory receptor proteins are NOT dedicated
to single odorants
b. Different olfactory receptor proteins respond
differently to the same odorants
c. Across-Fiber Pattern Code (not a labeled line)
Information conveyed by relative amount of
activity across multiple, differentially
sensitive elements in an array.

83
Q

CN I -

A

Olfactory Nerve/Tract

84
Q

The olfactory tract enters the
brain at the junction between
the (2) and divides into two pathways.

A

midbrain and the cerebrum

85
Q

The olfactory tract enters the
brain at the junction between
the midbrain and the cerebrum
and divides into two pathways (2)

A

Medial Olfactory Area/ Primitive Olfactory System

Lateral Olfactory Area

86
Q

Medial Olfactory Area/ Primitive Olfactory System

A

to hypothalamus
and limbic system for
olfactory reflexes

87
Q

Lateral Olfactory Area (2)

A 
i. The Less Old 
Olfactory System: to 
limbic system 
(hippocampus) 
ii. Newer System: to 
orbitofrontale cortex
88
Q

The Less Old

Olfactory System

A

Automatic but learned control of food
intake and aversion to toxic and unhealthy
foods

89
Q

Newer System

A

Conscious perception and analysis of

olfaction.

90
Q

information is transmitted from the olfactory bulb by axons

of

A

mitral and tufted relay neurons in the lateral olfactory
tract

91
Q

Gustation (6)

A
  • Normogeusia
  • Hypogeusia
  • Hypergeusia
  • Parageusia
  • Taste Agnosia
  • Ageusia
92
Q

Olfaction (6)

A
  • Normosmia
  • Hyposmia
  • Hyperosmia
  • Parosmia
  • Olfactory Agnosia
  • Anosmia
93
Q

Gustatory Disorders

1. Generally not associated with

A

aging

94
Q

Gustatory Disorders

Complaints often due to (3)

A

olfactory, salivary,

or neurologic dysfunction

95
Q

Gustatory Disorders

Oral products and medications can alter

A

taste (& smell)

96
Q

Olfactory Disorders

1. Frequently associated with

A

aging
May be better predictor of Alzheimer’s
Disease & other dementias than global
cognitive tests

Physiology (53 decks)

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