Chemical Senses Lec09 Flashcards Preview

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Flashcards in Chemical Senses Lec09 Deck (67)
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1
Q

____ has no major, direct cortical
projections or thalamic input

A

Olfaction

2
Q

Olfactory Epithelium has 3 cells: 

A

 basal (stem) cells, neurons, & supporting cells

3
Q

___ cells in the olfactory epithelium renew every 30 days

A

basal

4
Q

neurons in the olfactory epithelium are ___polar

A

bipolar

5
Q

what do neurons of the olfactory epithelium need to survive? 

A

contact with & tropic support from olfactory bulb to survive

6
Q

describe signal transduction of smell

A

--> odorant binds to G-protein receptor (R)


--> G protein (G) & adenyl cyclase (AC) increase


--> cAMP levels increase


--> cyclic nucleotide gated (CNG) ion channel opens

--> cell depolarizes

7
Q

key ion in smell pathway?>

A

calcium

8
Q

Humans have about ___ odorant receptors 

A

1000

9
Q

1 neuron = ___ odorant receptor type

A

1

10
Q

1 odorant receptor type recpgnizesone ___

A

compoenent of an odorant molecule

11
Q

odorant encoding is based on a

A

pattern of responses

*not single neurons

12
Q

what are the 4 layers of the olfactory bulb?

A

glomerular, external plexiform, mitral cell, granule cell

13
Q

what layers in the olfactroy bulb go right to the olfactory cortex

A

mitral and tufted cells 

14
Q

___ and ___ cells are inhibitory interneurons that modulate mitral & tufted cells

A

periglomerular and granule 

15
Q

what is the outermost layer?

A

periglomerular

16
Q

olfactory neurons projections to CNS is either

A

1) quadrant-to- quadrant

(2) same-OR-neurons-to-same-glomerulus

17
Q

 weak stimulations are removed via ____ cells, so only the most sensitive / maximally stimulated neuron responds to an odorant.

A

granule cells

18
Q

Each glomerulus recognizes different ___

A

odorants

19
Q

each odorant receptor  recognizes a specific

A

 "odotope"

20
Q

Odors are identified by overall activation pattern of 

A

glomeruli across the whole bulb

21
Q

taste invovles innervation by what cranial nerves

A

7, 9, 10

22
Q

Gustatory axons innervate the nucleus of the
___ in brainstem

A

solitary tract (NTS)

23
Q

the solitary n. of the braisntem projects to the

A

VPM in the thalamus

24
Q

what cranial nerve converys oral irratation (the common chemical sense)

A

trigem 

25
Q

Four primary taste fields = areas of \

A

greatest sensitivity

26
Q

Taste buds are all on ___.

A

papillae

27
Q

 Each bud has ___ receptor & basal (stem) cells

A

50-100

28
Q

Microvilli on ___ taste cells get initial stimulus 

A

Type II

29
Q

Microvilli on Type II taste cells get initial stimulus then goes to

A

gap junctions

30
Q

Microvilli on Type II taste cells get initial stimulus --> gap junction --> ___ cells

A

type III

31
Q

type III cells pass synaptic transmission to 

A

gustatory afferent axons

32
Q

what tastes use IONIC Transduction Mechanisms

A

sweet and sour

33
Q

Sweet, Bitter, and Umami (amino acids) use Receptor-Mediated Transduction via___

A

 2nd
Messengers

34
Q

Pattern code theory of taste encoding 

A

 tastes are encoded by differential firing pattern across a population of axons.

35
Q

what supports pattern code theory of taste encoding 

A

 supported by single axons responding to many different
primary stimuli, although they have a maximal response
to only one stimulus.

36
Q

what is the labeled line theory of taste encoding 

A

 each neuron/axon is responsible for one specific taste.

37
Q

what supports the labeled line theory of taste encoding 

A

specific gene knockouts that can rescue
or delete the perception of individual taste qualities. 

ex. deletion of PLCβ2 causes loss of sucrose, glutamate, and quinine tastes.

38
Q

where are the cell bodies of the enurons that transduce odors?

A

in the olfactory epithelium

39
Q

 In humans the OE lines the posterodorsal part of the nasal cavity below the

A

 cribriform plate

40
Q

The OE neurons relay information via axonal projections through the cribriform plate to the ___

A

olfactory bulb

41
Q

 Bulbar neurons project to the___

A

 piriform  cortex

42
Q

 Bulbar neurons project via the ____ to the piriform cortex

A

lateral olfactory tract

43
Q

where does the oflactory sensory information go to after leaving the piriform cortex? 

A

1. to parts of the neocortex via the mediodorsal nucleus of the thalamus

2. and to the lateral hypothalamus.

44
Q

each neuron in the oflactory epithelium has a ___ axon that projects to the bulb 

A

c fiber (a thin unmyelinated axon)

45
Q

epithelial projections are continually being broken down and reforming due to

A

basal cells always undergoing mitotic division in stem cell mode

46
Q

All of the G protein activating receptors have a common tertiary structure with___ transmembrane domains

A

 7

47
Q

Neurons expressing a particular OR are located where? 

A

they are  limited to a particular region (or zone) of the epithelium. 

48
Q

Within a zone, neurons expressing a particular OR can be either:

A

homogeneously distributed or have a clustered distribution pattern.

49
Q

the___ a neuron expresses determines the physiological responsiveness of that neuron.

A

 particular odorant receptor

50
Q

any one OR is broadly tuned to respond to a lot of different odorants, which share a 

A

common molecular feature.

51
Q

each ___ has a unique pattern of spatial activity

A

odorant

52
Q

order of the layers of the olfactory bulb (from closests to farthest from the sensory neuron)

A

glomerular layer, external plexiform layer, mitral cell layer and granule cell layer.

53
Q

periglomeruli cells cluster around

A

glomeruli

54
Q

Unlike other sensory systems the projection of the sensory surface onto its central structures is not

A

NOT  point-to-point.

55
Q

olfactory neurons are ___ tuned 

A

broadly

56
Q

where is there pattern activation in response to odorants?

A

1. in the epihtelium

2. in the bulb

57
Q

in the consensus working model

there are many different ORs and each would recognize a___) that would be considered an “odotope

A

 single chemical moiety (e.g., a phenyl group

58
Q

A single chemical would be composed of how many odotypes?

A

many

59
Q

How many odotopes are there likely to be? 

A

As many as there are OR types.

60
Q

under the ___ model..

Odors would be identified and discriminated by the overall activation of glomeruli across the whole bulb.

A

consensus working

61
Q

what does the solitary n. projec tto

A

1. vpm

2. hypothalamus

3. amygdala

62
Q

what are the 4 primary taste fields? 

A

The circumvallate, foliate and fungiform papillae, as well as taste buds

63
Q

what do all taste fields respond to?

A

all tastants

64
Q

each___ is most sensitive to a particular taste quality. 

A

 taste field

65
Q

Salt and sour stimuli are transduced through an ionic transduction mechanism which results in an intracellular increase in _____ and transmitter release.

A

calcium

66
Q

with sweet, bitter, umami, 

increases in ___ stimualte a TRPM5 calcium channel 

A

camp

67
Q

with sweet, bitter, umami ncreases in cAMP stimulate a TRPM5 calcium channel via ___

A

IP3.