Chemical Senses Lec09

Question 1

____ has no major, direct cortical
projections or thalamic input

Answer 1

Olfaction

Question 2

Olfactory Epithelium has 3 cells:

Answer 2

basal (stem) cells, neurons, & supporting cells

Question 3

___ cells in the olfactory epithelium renew every 30 days

Answer 3

basal

Question 4

neurons in the olfactory epithelium are ___polar

Answer 4

bipolar

Question 5

what do neurons of the olfactory epithelium need to survive?

Answer 5

contact with & tropic support from olfactory bulb to survive

Question 6

describe signal transduction of smell

Answer 6

–> 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

Question 7

key ion in smell pathway?>

Answer 7

calcium

Question 8

Humans have about ___ odorant receptors

Answer 8

1000

Question 9

1 neuron = ___ odorant receptor type

Answer 9

1

Question 10

1 odorant receptor type recpgnizesone ___

Answer 10

compoenent of an odorant molecule

Question 11

odorant encoding is based on a

Answer 11

pattern of responses

*not single neurons

Question 12

what are the 4 layers of the olfactory bulb?

Answer 12

glomerular, external plexiform, mitral cell, granule cell

Question 13

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

Answer 13

mitral and tufted cells

Question 14

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

Answer 14

periglomerular and granule

Question 15

what is the outermost layer?

Answer 15

periglomerular

Question 16

olfactory neurons projections to CNS is either

Answer 16

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

Question 17

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

Answer 17

granule cells

Question 18

Each glomerulus recognizes different ___

Answer 18

odorants

Question 19

each odorant receptor recognizes a specific

Answer 19

“odotope”

Question 20

Odors are identified by overall activation pattern of

Answer 20

glomeruli across the whole bulb

Question 21

taste invovles innervation by what cranial nerves

Answer 21

7, 9, 10

Question 22

Gustatory axons innervate the nucleus of the
___ in brainstem

Answer 22

solitary tract (NTS)

Question 23

the solitary n. of the braisntem projects to the

Answer 23

VPM in the thalamus

Question 24

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

Answer 24

trigem

Question 25

Four primary taste fields = areas of \

Answer 25

greatest sensitivity

Question 26

Taste buds are all on \_\_\_.

Answer 26

papillae

Question 27

Each bud has ___ receptor & basal (stem) cells

Answer 27

50-100

Question 28

Microvilli on ___ taste cells _**get initial stimulus** _

Answer 28

Type II

Question 29

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

Answer 29

gap junctions

Question 30

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

Answer 30

type III

Question 31

type III cells pass synaptic transmission to

Answer 31

gustatory afferent axons

Question 32

what tastes use IONIC Transduction Mechanisms

Answer 32

sweet and sour

Question 33

**_Sweet, Bitter, and Umami_** (amino acids) use Receptor-Mediated Transduction via\_\_\_

Answer 33

2nd Messengers

Question 34

Pattern code theory of taste encoding

Answer 34

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

Question 35

what supports pattern code theory of taste encoding

Answer 35

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

Question 36

what is the labeled line theory of taste encoding

Answer 36

each neuron/axon is responsible for one specific taste.

Question 37

what supports the **_labeled line_** theory of taste encoding

Answer 37

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.

Question 38

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

Answer 38

in the olfactory epithelium

Question 39

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

Answer 39

cribriform plate

Question 40

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

Answer 40

olfactory bulb

Question 41

Bulbar neurons project to the\_\_\_

Answer 41

piriform cortex

Question 42

Bulbar neurons project via the ____ to the piriform cortex

Answer 42

lateral olfactory tract

Question 43

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

Answer 43

1. to parts of the **neocortex** via the mediodorsal nucleus of the thalamus 2. and to the **lateral hypothalamus.**

Question 44

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

Answer 44

c fiber (a thin unmyelinated axon)

Question 45

epithelial projections are continually being broken down and reforming due to

Answer 45

basal cells always undergoing mitotic division in stem cell mode

Question 46

All of th**e G protein activating receptors** have a common tertiary structure with\_\_\_ transmembrane domains

Answer 46

7

Question 47

Neurons expressing a particular OR are located where?

Answer 47

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

Question 48

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

Answer 48

homogeneously distributed or have a clustered distribution pattern.

Question 49

the\_\_\_ a neuron expresses determines the physiological responsiveness of that neuron.

Answer 49

particular odorant receptor

Question 50

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

Answer 50

common molecular feature.

Question 51

each ___ has a unique pattern of spatial activity

Answer 51

odorant

Question 52

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

Answer 52

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

Question 53

periglomeruli cells cluster around

Answer 53

glomeruli

Question 54

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

Answer 54

NOT point-to-point.

Question 55

olfactory neurons are ___ tuned

Answer 55

broadly

Question 56

where is there pattern activation in response to odorants?

Answer 56

1. in the epihtelium 2. in the bulb

Question 57

in the **consensus working model** there are many different ORs and each would recognize a\_\_\_) that would be considered an “odotope

Answer 57

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

Question 58

A single chemical would be composed of how many odotypes?

Answer 58

many

Question 59

How many odotopes are there likely to be?

Answer 59

As many as there are OR types.

Question 60

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

Answer 60

consensus working

Question 61

what does the solitary n. projec tto

Answer 61

1. vpm 2. hypothalamus 3. amygdala

Question 62

what are the 4 primary taste fields?

Answer 62

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

Question 63

what do all taste fields respond to?

Answer 63

all tastants

Question 64

each\_\_\_ is most sensitive to a particular taste quality.

Answer 64

taste field

Question 65

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

Answer 65

calcium

Question 66

with sweet, bitter, umami, increases in ___ stimualte a TRPM5 calcium channel

Answer 66

camp

Question 67

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

Answer 67

IP3.