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Neuro > OLFACTION > Flashcards

OLFACTION Flashcards

0
Q

trigeminal nerve endings in

A

mucous membrane in mouth

much less sensitive

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1
Q

part of NS dedicated to detection of chemicals

A

trigeminal
olfactory
gustatory

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2
Q

trigeminal purpose

A

sensing noxious chemicals such as vinegar, ammonia, etch

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3
Q

capsacin activates

A

a TRP ion channel that lets Na and Ca flow through
depolarizes nocicpetor fibers which makes you sense pain and heat
also activated by heat–can be desensitized

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4
Q

reasons why olfactory system

A

broad discrimitory powers

high sensitivity to odorants

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5
Q

average human thresholds

A

10^-12 –> 10^14

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6
Q

at 50-70 years of age..

A

our olfactory capabilities are less than 50%

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7
Q

anosmia

A

selective deficits in olfactory sensitivity

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8
Q

androstadienon

A

male hormone in sweat that promotes mood and arousal

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9
Q

vomeronasal organ

A

plays an important role in pheromone detection in many animals, but not humans
–many animals there is a small pit in the roof of the mouth that contains epithelial tissue and pheromone receptor cells

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10
Q

most of the nasal epithelium

A

respiratory epithelium cilitated respiratory cells, and goblet cells that secrete mucous

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11
Q

olfactory receptor cells are restricted to

A

upper concha and part of middle one

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12
Q

olfactory epithelium appearance

A

yellowish pigmentation, thought to be due to accumulation of carotinoid pigment (no functional effect)

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13
Q

three types of cells in olfactory system

A

1) basal cells
2) support cells
3) receptor cells

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14
Q

basal cells

A

precursors of receptor cell populations that undergoes continual turnover
average lifespan about 60 days (entire population turns over every 6-8 weeks)

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15
Q

support cells

A

apical surface with microvilli, isolate and support receptor cells, and may have nutritional role

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16
Q

receptor cells

A

soma with distal dendrite projecting to epithelial surface and an unmyelinated axon that aggregates with others into fasicles–>become ensheathed in schwann cells and form olfactory nerve (cranial nerve I) before passing through cartilaginous and porous cribiform plate and forming synapses in the olfactory bulb of CNS

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17
Q

mucous layer is

A

replaced every ten minutes

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18
Q

olfactory bulb

A

contains spherical structures called glomeruli, which are endings of receptor cell axons and mitral cell dendrites

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19
Q

mitral cells

A

principal projection neurons of olfactory bulb, and are the only ones to project to other regions of brain
**have a high degree of convergence at first synapse of system

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20
Q

oral extremity of the epithelium projects

A

mainly to anterior bulb

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21
Q

aboral epithelium

A

posterior portion

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22
Q

continual neurogenesis

A

population of receptor cells turns over every 6-8 weeks

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23
Q

olfactory sensitivity is in part due to

A

large numbers of olfactory receptor cells

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24
Q

olfactory neurons respond to odorant stimulation..

A

with a change in rate at which fire action potentials (thought to arise in change in membrane conductance of receptor cell–> depolarization to threshold)

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25
Q

what is signal transduction?

A

changing a chemical signal to an electrical one

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26
Q

where does signal transduction occur?

A

in the cilia

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27
Q

odorant receptors are

A

GPCR with 7 membrane spanning regions–>activate ion channels in cilia –>some cause changes in adenylate cyclase activity and cAMP

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28
Q

phospholipase C mechanism

A

rapid increase in membrane lipid phosphotidylinositol via phospholipase C–>IP3–>open Ca2+ selective channels

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29
Q

an olfactor cell may respond to

A

one odorant or many

–>thresholds of detection may differ by order of magnitude

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30
Q

olfactory epithelium acts as a “gas chromatograph”

A

sorts out molecules and is absorbed in different epithelium domains

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31
Q

receptor neurons expressing same odorant receptor converge in

A

same glomerulus

32
Q

odorants represented in epithelium by``

A

patterns correlated with odorant identity adn concentration

33
Q

across fiber pattern

A

quality of odorant encoded in the pattern of activity in a large number of cells simultaneously
–>pattern includes not only which cells are active, but their temporal pattern of activity, as well

34
Q

central processing in olfactory cortex

A

cortical neurons receive inputs from more than one glomerulus–>allows to integrate inputs from multiple olfactory receptor proteins that can detect the same odorant

35
Q

comparison neurons

A

respond to a mix of two odorants, but are not stimulated by either of the odorants when present individually

36
Q

why is olfaction unique

A

doesnt necessarily go through thalamus on the way to 6-layered cortex

37
Q

central projection of olfactory information

A

mitral cells–>olfactory tract–>olfactory tubercle–>piriform cortex–>entorhinal cortex

38
Q

info to the amygdala

A

to the hypothalamus

emotional and motivational aspects of odor sensation

39
Q

info to thalamus

A

goes to frontal lobe

olfactory perceptions and discrimination occurs

40
Q

info to entorhinal cortex

A

goes to hippocampus

(with amygdala) serves as a mechanism by which we remember odors and specific emotional responses coupled to tehm

41
Q

adrenergic fibers

A

provide input involved in heightened sense of smell during fear and excitement

42
Q

inputs from olfactory bulb–>locus ceruleus

A

emotional state influences the perception of odors–>may be a part of increased sensitivity to smell of food when hungry

43
Q

flavor is

A

information from taste receptors, thermoreceptors, pain receptors, and mechanoreceptors in mucous membranes of mouth and tongue

44
Q

5 groups of taste

A 
sweet
sour
bitter
salt
umami
45
Q

umami

A

taste of L-glutamate or MSH

helps signal presence of protein-rich foods

46
Q

where are taste receptors located

A

tongue

back of mouth and pharynx (palate, epiglottis, esophagus)

47
Q

papillae

A 
peg like projections covering the tongue
4 types are
filoform
circumvallate
foliate
fungiform
48
Q

filoform

A

cover much of surface of tongue

no taste buds

49
Q

circumvallate

A

have ~7-12 of these round structures across the back of the tongue
-250 taste buds each (half of the tastebuds in humans)

50
Q

foliate

A

arranged in closely packed folds along back edges/side of tongue
-often more well developed in children, barely detectable in adults

51
Q

fungiform

A

scattered across entire surface of the tongue

52
Q

supertasters

A

increased sensitivity to bitter substances than average individuals
–appear to have a higher density of fungiform papillae on their tongue

53
Q

how many taste buds in humans

A

4000

54
Q

three types of cells in taste buds

A

support cells
basal cells
receptor cells

55
Q

basal cells are

A

progenitor cells that give rise to taste receptor cells

56
Q

receptor cells are

A

continously turned over
average lifetime of 10 days–>unlike olfactory receptor cells, taste receptor cells do not have axons that convey information centrally..they are secondary sensory cels

57
Q

innervation of taste receptors

A

facial nerve
glossopharngeal nerve
vagus nerve

58
Q

path of taste buds

A

facial, glossopharyngeal, vagal–>base of sensory cells–>nucleus of solitary tract–>vpm nucleus of thalamus–>gustatory cortex in temporal lobe, hypothalamus & amygdala

59
Q

circumvallate & foliate innervated by

A

glossopharyngeal

60
Q

fungiform innervated by

A

facial

61
Q

Different sensitivity of regions of the tongue

A

Bitter- near back or base (circumvallate)
sour- edges (foliate)
sweet and salty- tip- facial

62
Q

salt receptors

A

voltage insensitive Na channels
normly open and some Na ions leak into cell: taste stimuli–>increase in Na ions in extracellular fluid–>increase in leak–>depolarization of taste receptor cell

63
Q

what drug blcosk salt sensitive channels

A

amiloride

64
Q

sour taste

A

degree of sourness depends on proton level–>protons open up cation selective ion channel–>cell becomes depolarized

65
Q

sweet receptors

A

specific GPCR for sweet molecules–>increase phospholipase C–>generation IP3–>release of Ca frm internal stores and transmitter release

66
Q

bitter receptors

A

involve a second messenger mediated release of Ca internal stores
but different receptors than sweet

67
Q

umami

A

truncated version of metabotropic glutamate receptor (large portion of extracellular domain, including glutmate binding site is msising)
–>linked to a second messenger cascade

68
Q

NT and taste

A

recent evidence that taste receptor cell function and responsiveness are modulated by extrinsic factors, such as NT and hormones, providing a way in which emotional state (hunger) may influence taste responses

69
Q

NT that enhance taste cell responses

A

5HT

CCK

70
Q

enhance taste cell respnses to NaCl

A

aldosterone, vasopressin

71
Q

salivation, coughing, gagging pathway

A

projections to nucleus of solitary tract->VPM of thalamus–>temporal lobe in insula (gustatory cortex)

72
Q

tactile information

A

gustatory information to insula

73
Q

atrophic rhinitis

A

reduced olfactory abilities

74
Q

diabetes

A

reduced olfactory abilities

75
Q

chronic renal failure

A

reduced olfactory adn gustatory abilities

76
Q

Alzheimer’s disease

A

reduced olfactory abilities (loss of receptor cells)

77
Q

cystic fibrosis

A

enhnaced olfactory and gustatory abilities

78
Q

epilepsy

A

enhanced olfactory and gustatory abilities

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