Chemical Senses Lec09 Flashcards Preview

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Flashcards in Chemical Senses Lec09 Deck (67):
1

____ has no major, direct cortical
projections or thalamic input

Olfaction

2

Olfactory Epithelium has 3 cells: 

 basal (stem) cells, neurons, & supporting cells

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3

___ cells in the olfactory epithelium renew every 30 days

basal

4

neurons in the olfactory epithelium are ___polar

bipolar

5

what do neurons of the olfactory epithelium need to survive? 

contact with & tropic support from olfactory bulb to survive

6

describe signal transduction of smell

--> 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

key ion in smell pathway?>

calcium

8

Humans have about ___ odorant receptors 

1000

9

1 neuron = ___ odorant receptor type

1

10

1 odorant receptor type recpgnizesone ___

compoenent of an odorant molecule

11

odorant encoding is based on a

pattern of responses

*not single neurons

12

what are the 4 layers of the olfactory bulb?

glomerular, external plexiform, mitral cell, granule cell

13

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

mitral and tufted cells 

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14

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

periglomerular and granule 

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15

what is the outermost layer?

periglomerular

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16

olfactory neurons projections to CNS is either

1) quadrant-to- quadrant

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

17

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

granule cells

18

Each glomerulus recognizes different ___

odorants

19

each odorant receptor  recognizes a specific

 "odotope"

20

Odors are identified by overall activation pattern of 

glomeruli across the whole bulb

21

taste invovles innervation by what cranial nerves

7, 9, 10

22

Gustatory axons innervate the nucleus of the
___ in brainstem

solitary tract (NTS)

23

the solitary n. of the braisntem projects to the

VPM in the thalamus

24

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

trigem 

25

Four primary taste fields = areas of \

greatest sensitivity

26

Taste buds are all on ___.

papillae

27

 Each bud has ___ receptor & basal (stem) cells

50-100

28

Microvilli on ___ taste cells get initial stimulus 

Type II

29

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

gap junctions

30

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

type III

31

type III cells pass synaptic transmission to 

gustatory afferent axons

32

what tastes use IONIC Transduction Mechanisms

sweet and sour

33

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

 2nd
Messengers

34

Pattern code theory of taste encoding 

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

35

what supports pattern code theory of taste encoding 

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

36

what is the labeled line theory of taste encoding 

 each neuron/axon is responsible for one specific taste.

37

what supports the labeled line theory of taste encoding 

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

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

in the olfactory epithelium

39

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

 cribriform plate

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40

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

olfactory bulb

41

 Bulbar neurons project to the___

 piriform  cortex

42

 Bulbar neurons project via the ____ to the piriform cortex

lateral olfactory tract

43

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

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

2. and to the lateral hypothalamus.

44

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

c fiber (a thin unmyelinated axon)

45

epithelial projections are continually being broken down and reforming due to

basal cells always undergoing mitotic division in stem cell mode

46

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

 7

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47

Neurons expressing a particular OR are located where? 

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

48

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

homogeneously distributed or have a clustered distribution pattern.

49

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

 particular odorant receptor

50

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

common molecular feature.

51

each ___ has a unique pattern of spatial activity

odorant

52

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

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

53

periglomeruli cells cluster around

glomeruli

54

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

NOT  point-to-point.

55

olfactory neurons are ___ tuned 

broadly

56

where is there pattern activation in response to odorants?

1. in the epihtelium

2. in the bulb

57

in the consensus working model

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

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

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58

A single chemical would be composed of how many odotypes?

many

59

How many odotopes are there likely to be? 

As many as there are OR types.

60

under the ___ model..

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

consensus working

61

what does the solitary n. projec tto

1. vpm

2. hypothalamus

3. amygdala

62

what are the 4 primary taste fields? 

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

63

what do all taste fields respond to?

all tastants

64

each___ is most sensitive to a particular taste quality. 

 taste field

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65

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

calcium

66

with sweet, bitter, umami, 

increases in ___ stimualte a TRPM5 calcium channel 

camp

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67

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

IP3.