Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Dental Neuroscience > chemical sensation (smell and taste) > Flashcards

chemical sensation (smell and taste) Flashcards

1
Q

the chemical senses

A
  • olfaction (smell)
  • gustation (taste)
  • stimulated by chemical molecules
  • complement each other as visceral afferents
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

olfaction

A
  • sense of smell
  • ariborne odorants
  • 100,000 unique odors
  • noxious odorants tend to be deleterious
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what properties do odorants need to be detected?

A
  • volatility
  • water solubility
  • lipid solubility
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is volatility?
why is volatility is important?

A
  • ability to evaporate under normal temp
  • so it can be sniffed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

water solubility is important…

A

so that it can diffuse through the olfactory epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

lipid solubility is important…

A

so that it will interact with the lipids of the membranes of olfactory receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

which chemical can be detected in low concentrations in the air?
what is it used for

A
  • t-butyl mercaptan
  • added to natural gas to detect leaks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

adaptation to odors occurs

A

quickly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what do odorants interact with? where do they interact?

A
  • olfactory receptor neurons (ORNs)
  • olfactory epithelium in the nose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

cells of olfactory epithelium

A
  • olfactory receptor neurons (ORNs)
  • basal cells
  • supporting cells
  • Bowman’s glands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

basal cells

A

the stem cells that continuously give rise to new ORNs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Bowman’s glands produce

A

mucus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

olfactory receptor neurons (ORNs) characteristics

A
  • bipolar
  • have cilia
  • unmyelinated
  • fire action potentials
  • cilia are located in the mucus layer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what layer do odorants have to dissolve through to reach sensory cilia?

A

mucous layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are ORNs?

A
  • only neuron in the nervous system that are replaced regularly throughout life (every 4-8 weeks)
  • about 10,000
  • each one only expresses one type of receptor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

odorant receptors are

A
  • g-protein coupled receptors
  • have 7 transmembrane domains
  • have about 400 different receptors
  • similar to visual pigments
  • can recognize more than one odorant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

generation of receptor potentials in response to odors takes place in

A

the cilia of ORNs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

effect of odorants on nerves

A
  • large current when applied to cilia
  • small current when applied to cell body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

odor transduction mechanism

A
  1. odorant molecule binds to specific g-protein coupled receptors in plasma membrane of olfactory cilia
  2. activates adenylate cyclase and generates cAMP
  3. cAMP targets Na/Ca channel
  4. depolarization
  5. opening of Ca gated Cl channel
  6. depolarization of olfactory receptor potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

coding of olfactory system

A
  • use of combinations
  • coding of identities of odors
  • single receptor can recognize multiple odorants
  • different odorants are recognized by different combinations of receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

glomeruli are

A

balls of tangled connections between mitral cells and ORNs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is a hallmark of glomeruli

A

they are formed exclusively by axons bearing the same odorant receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

each glomerulus defines

A

a module that processes the sensory information related to a given odorant receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

structure of the olfactory system

A

signals are sent to
- primary olfactory (pirioform) cortex in temporal lobe
- secondary olfactory (orbitofrontal cortex) in frontal lobe
- amygdala deep in cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

the olfactory system does not include:

A

thalamic relay from primary receptors en route to the cortical region that processes the sensory information

26
Q

olfaction abnormalities

A
  • anosmia
  • hyposmia
27
Q

anosmia

A

absence of sense of smell

28
Q

hyposmia

A

diminished olfactory sensitivity

29
Q

olfactory thresholds _________ with age. more than 75% of humans over 80 have ________________________________________________________________.

A

increases
impaired ability to identify smells

30
Q

relative size of olfactory bulb

A

0.01% of human brain volume
2% of mouse brain volume
human bulb is much larger than mouse bulb

31
Q

humans have _________ glomeruli in the olfactory bulb than rodents.

A

more

32
Q

the gustatory system

A
  • detects ingested, primarily water-soluble, molecules called tastants
33
Q

tastants

A

provide information about the quality, quantity, and safety of ingested food

34
Q

taste buds

A

are the sensory organs of the taste system

35
Q

taste buds are located in

A

different types of papillae (protrusions on the surface of the tongue)

36
Q

types of papillae

A
  • circumvallate (50%)
  • fungiform (25%)
  • foliate (25%)
  • filiform
37
Q

taste buds are located in

A
  • tongue
  • hard palate
  • soft palate
  • pharynx
  • larynx
  • epiglottis
  • can also be in stomach, gut, pancreas
38
Q

taste bud structure

A
  • a pore
  • have gustatory cells
  • basal cells (sensory)
  • supporting cells
39
Q

taste receptor cells (gustatory cells) have

A
  • microvilli on apical surface
  • synaptic vesicles at basal surface
  • average life span of only 10 days
  • constantly replenished by basal cells
40
Q

basic taste qualities

A
  • salty
  • sour
  • sweet
  • bitter
  • umami
41
Q

umami

A

a Japanese word for the taste of monosodium glutamate (MSG) or more generally amino acid (meat) taste

42
Q

sweet and umami are

A
  • appetitive and generally attractive to animals
  • allow identification of energy rich nutrients
43
Q

bitter and sour taste

A
  • innately aversive
  • allow identification of potentially noxious chemicals
44
Q

salty

A
  • unique in increasing salt concentration
  • transforms innately appetitive stimulus into a powerfully aversive one
45
Q

is there a tongue map?

A

used to be but outdated and not used
- all parts of the tongue with taste buds will respond to taste categories

46
Q

mechanism of taste transduction classes

A
  • direct action of the tastants on ion channels
  • coupling of tastant receptors to ion channels through 2nd messenger pathways involving GPCRs
47
Q

direct sensory transduction

A
  • salt, sour
    1. chemicals enter taste cells through ion channels in apical domain
    2. depolarization
    3. Na/K and Ca channels release neurotransmitters form presynaptic specializations at base of cell to terminals (Na in, K out, Ca in)
    4. ER also release Ca into cell
    5. release of neurotransmitter
48
Q

coupling sensory transduction

A
  • sweet, bitter, umami
    1. chemicals bind to G-protein coupled receptor in apical domain
    2. G proteins signal secondary messengers
    3. Na, K, Ca, and TRPM channels open (Na in, K out, Ca in, TRPM in)
    4. ER also releases calcium into cell
    5. release of neurotransmitter
49
Q

receptor mediation of salt

A
  • Na ions enter receptor
  • depolarization
  • candidate channels are similar to epithelium sodium channels (ENaCs)
  • voltage INSENSITIVE
  • blocked by diuretic compound amiloride
50
Q

receptor mediation of sour

A
  • sour is produced by high concentration of protons in acidic foods
  • acid = H+
  • H+ blocks K channels
  • blockage = depolarization
51
Q

receptor mediation of sweet, bitter, umami

A
  • mediated by GPCRs
  • act through PLC and IP3
  • release Ca from internal stores
  • opening of TRPM5 channel
  • depolarization
52
Q

T1R2 + T1R3 receptors trandsuce

A

sweet taste

53
Q

T1R1 + T1R3 receptors transduce

A

umami taste

54
Q

T2R receptors transduce

A

bitter taste

55
Q

taste pathways in CNS

A
  • primary sensory neurons comprise CN VII, IX, and X fibers
  • 1st order axons synapse is within solitary nucleus
  • 2nd order axons travel with medial lemniscus to synapse in VPM of thalamus
  • 3rd order axons synapse in gustatory cortex
56
Q

central pathway

A
  • all 3 CN carry taste to nucleus solitarius
  • then projects to VPM of thalamus
57
Q

basic pathways

A

nucleus solitarius > VPM > postcentral gyrus

nucleus solitarius > VPM > insula

nucleus solitarius > amygdala/hypothalamus

58
Q

use of in-vivo 2 photon calcium imaging demonstrates

A

topographic segregation of functional architecture of gustatory cortex
(each taste has a cortical field)

59
Q

taste perception has 2 theories:

A
  1. state that individual taste receptors respond to a single taste stimulus. this info is transmitted to specific populations of neurons within the taste pathway for perception of the taste quality
  2. individual taste receptors respond to more than one modality of taste
60
Q

recent studies have shown that

A
  • different taste modalities
  • activation of a single type of TRC is sufficient to encode taste quality, strongly supporting the labelled-line model

Dental Neuroscience (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions