chapter 16: chemical senses Flashcards

1
Q

define anosmia

A

loss of sense of taste and smell

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2
Q

name the three components of taste and smell

A
  • taste
  • olfaction
  • flavour (combination of taste and smell)
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3
Q

what is one property that distinguishes the chemical senses from vision, hearing and the cutaneous senses?

A

neurogenesis because molecules are exposed to environment

  • 5-7 weeks for olfactory receptors
  • 1-2 weeks for taste receptors
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4
Q

why are the chemical senses seen as “gatekeepers” of the body

A
  1. identify things the body needs for survival (smell/taste good)
  2. detect things that would be bad for the body (taste/smell unpleasant)
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5
Q

name the 5 basic taste sensation

A

salty, sour, sweet, bitter, umami

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6
Q

why is sweetness often associated with good components and bitter with bad components

A

sweet: nutritive + caloric value = automatic acceptance response
bitter: harmful substance = automatic rejection response

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7
Q

what happens when a person is deprived of sodium

A

seeks out food that taste salty to replenish the salt the body needs

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8
Q

name the four types of papillae that can be found on the tongue

A
  1. filiform (cones, entire surface)
  2. fungiform (mushroom, tip/sides)
  3. foliate (folds, back)
  4. circumvallate (flat mounds, back)
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9
Q

which papillae does not contain taste buds

A

filiform

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10
Q

explain how an electrical signal is generated in the taste cells

A

stimulus in contact with papillae → taste bud → made of taste cells → tips protrude into taste pore → transduction → electrical signal

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11
Q

name the 4 different types of nerves

A
  1. chorda tympani nerve (front and side)
  2. glossopharyngeal nerve (back)
  3. vagus nerve (mouth and throat)
  4. superficial petrosal nerve (top of mouth)
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12
Q

where do the fibers from the tongue, mouth and throat make connections

A

brain stem in the nucleus of the solitary tract

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13
Q

the primary taste cortex is composed of which part of the brain

A

insula and frontal operculum

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14
Q

what is another name for population coding

A

across-fiber patterns

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15
Q

explain the experiment that was done to prove population coding

A

2 substances with similar pattern should taste the same

  • ammonium chloride & potassium chloride similar
  • inflicted shock for one of them = avoid the other too
  • chooses sodium chloride instead bc different pattern
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16
Q

explain Mueller’s experiment that supports specificity coding

A
  • mice no PTC receptor = don’t avoid (normal)
  • mice with PTC receptor = avoid, bitter (cloned)
  • mice w Cyx receptor = avoids Cyx (normal)
  • mice no Cyx receptor = don’t avoid (cloned)
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17
Q

what is the effect of amiloride

A
  • blocks the flow of sodium into taste receptors
  • ↓ neuron response in the brainstem
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18
Q

what mechanisms may be responsible for individual differences in taste

A
  1. higher density in taste buds = can taste more
  2. presence of specialized receptors
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19
Q

differentiate between a microsmatic and macrosmatic person

A

microsmatic: having poor sense of smell that is not crucial to survival
macrosmatic: having well-developed sense of smell

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20
Q

what method is used to find the detection threshold for odors

A

forced-choice method

  • one trial with weak odorant and other no odorant
  • Ps indicate which trial has stronger smell
  • threshold = correct response on 75% trials
21
Q

true or false? difficulty to accurately identify odors results from a deficiency in our olfactory system

A

false, it results from inability to retrieve the odor’s name from our memory

22
Q

name some genetically determined individual differences in odor perception

A
  • smell of steroid androsterone different for each person
  • sensitive to B-ionone = fragrant, floral
  • less sensitivity to B-ionone = sour, pungent, acid
23
Q

decrease in olfaction is a predictor of which disease

A

Alzheimer’s

24
Q

what is one explanation for why COVID causes a decrease in olfaction

A

COVID molecules attach to ACE2 found in intestines, lungs, arteries, heart and nose

25
Q

what is the function of sustentacular cells

A

provide metabolic and structural support to the olfactory sensory neurons

26
Q

explain the progression of symptoms related to AD

A

decrease in biomarkers before cognition decrease (MCI)

27
Q

name two reasons that make it difficult to identify odors

A
  • lack of specific language for odor quality
  • molecules with similar structures can smell different and molecules with different structures can smell the same
28
Q

what are odor objects

A

coffee, bacon, rose, dog, etc

29
Q

perceiving odor objects involves 2 stages. what are they

A
  1. analyzing (olfactory mucosa and olfactory bulb)
  2. synthesizing (olfactory cortex)
30
Q

what is the olfactory mucosa

A

dimed-sized region located on the roof of the nasal cavity below the olfactory bulb

31
Q

describe the structure of the olfactory system

A

molecules in contact with mucosa → contains olfactory receptor neurons (ORNs) → contains olfactory receptors → electrical signal → glomeruli in olfactory bulb

32
Q

approximately, how many types of olfactory receptors are there?

A

400

33
Q

explain the method of calcium imaging

A

to match odorant to specific ORN

  • olfactory receptor responds = ↑ calcium ions
  • ↑ calcium ions = ↓ fluoresce glow
  • measure ↓ glow to measure how strongly ORN is activated
34
Q

what is the odorant’s recognition profile

A

pattern of activation for each odorant

35
Q

true or false? each glomerulus collects info about the firing of a particular type of ORN

A

true

36
Q

name the two main olfactory areas

A
  1. piriform cortex
  2. orbitofrontal cortex
37
Q

what is the difference in activity between the olfactory bulb and the piriform cortex

A

odorants cause activity in specific locations in the olfactory bulb but cause widespread activity in PC

  • because projection from olfactory bulb is scattered
38
Q

explain the technique called functional ultrasound imagery

A

measure change in blood flow to determine brain activation

39
Q

how does the formation of odor objects occur

A
  • chemotopic map activated
  • scattered activation in PC
  • learning occurs: links created between scattered activation
40
Q

explain the Proust effect

A

ability of odors to trigger autobiographical memories

41
Q

true or false? in the experiment where Ps were asked to describe an event after being presented with either a picture or an odor, Ps who saw the picture rated their memories as more emotional than Ps who smelled the odor

A

false

42
Q

why does odor-evoked memories cause higher activity in the amygdala than word-evoked memories

A

olfactory nerve is 2 synapses away from amygdala (involved in creating emotions emotional memories) and 3 synapses away from hypothalamus (involved in storing and retrieving memories)

43
Q

what is the path that chemicals take to go from oral cavities to nasal cavities

A

retronasal route:

  • oral cavity
  • nasal pharynx
  • choana
  • olfactory mucosa
44
Q

define oral capture

A

sensations we experience from both olfactory and taste receptors are referred to the mouth

45
Q

the orbitofrontal cortex contains bimodal neurons. what are they?

A

neurons that respond to more than one sense

  • respond to similar qualities (same neuron that responds for smell and taste of sweet fruits)
46
Q

what region is considered the cortical center for detecting flavor and for perceptual representation of foods

A

orbitofrontal cortex

47
Q

what happens when cognition affects flavor

A

orbitofrontal cortex receives signal from both olfactory receptors and person’s expectations

48
Q

what is sensory-specific satiety

A

decline in pleasantness associated with a food that has been eaten to satiety

  • occurs in orbitofrontal cortex
  • similar effects in amygdala and insula
49
Q

differentiate the concepts of correspondence and influence

A

correspondence: property of a chemical sense is associated with property of other senses
influence: stimuli from one sense affect our perception or performance associated with another sense