Chapter 14-olfaction Flashcards

1
Q

Odor

A

The translation of a chemical stimulus into a smell sensation

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2
Q

Odorant

A

A molecule that is defined by its physiochemical characteristics, which are capable of being translated by the nervous system into the perception of smell; physical thing you smell

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3
Q

In order to be smelled, odorants must b

A

Volatile, small, hydrophobic

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4
Q

Human olfactory apparatus contains

A

Olfactory clefts and olfactory epithelium

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5
Q

Olfactory cleft

A

Narrow space at the back of the nose into which air flows

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6
Q

Olfactory epithelium

A

Mucous membrane in the human nose whose primary function is to detect odorants

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7
Q

Primary function of the nose

A

Breathe; filter, warm and humidify air that you breathe

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8
Q

Odor receptors sites are located where

A

On the cilia of olfactory sensory neurons where odorant molecules bind

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9
Q

Odor receptors are what kind of receptors

A

Chemoreceptors; receptive sites bind with molecules

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10
Q

Mitral cells receive projections from how many and what type of receptors

A

About 200, same type of receptor; convergent, lose spatial information

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11
Q

How many different receptor types are ther

A

About 1000, respond to distinct chemical molecules or parts of molecules

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12
Q

How many molecules are needed to activate odor receptors

A

7-8

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13
Q

Humans have how many receptors

A

6 million

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14
Q

Olfactory pathway

A

Olfactory bulb, Piriform cortex, entorhinal cortex, limbic system, orbitofrontal

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15
Q

Olfactory bulb

A

Olfactory info first processed here, 1 in each hemisphere that corresponds ipsilaterally to each nostril

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16
Q

Primary olfactory cortex also known as

A

Piriform cortex

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17
Q

Entorhinal cortex

A

Old, sensory association area, connect to the limbic system

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18
Q

Limbic system

A

Emotion (fear) and memory, base survival learning

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19
Q

Orbitofrontal cortex

A

Conscious perception and hedonics (liking)

20
Q

Shape pattern theory

A

Dominant biochemical theory for how chemicals come to be perceived as specific odors. Contends that different scents-as a function of odorant-shape to OR shape fit-activate different arrays of olfactory receptors in the olfactory epithelium. Population coding

21
Q

Population coding

A

Part of shape pattern theory; the various arrays produce specific firing patterns of neurons in the olfactory bulb, which then determine the scent we perceive

22
Q

Shape of odor molecule

A

Physical molecule

23
Q

Pattern of odor molecule

A

Which scent of odor receptor and to what degree, combination processing

24
Q

Chemical aromas

A

Smell odors that are not physically present; activate odor receptors, smell is an epiphenomenon (not directly representing physical world)

25
Q

How does population coding work

A

Odorants have different physical shapes that matter the most, and different colors (content) that also matter; receptors are selective to the shape and content of odorants

26
Q

Stereoisomers

A

Similar chemical compound but a different shape; result in different perceptual states-shape matters

27
Q

Odorant and receptor table: a given odorant will excite several receptors due to what

A

Its chemical composition

28
Q

Odorant and receptor table: a given receptor will respond to several odors, but the ___ of activity represents the composition of any given odor

A

Pattern

29
Q

Intensity

A

Certain receptors are more sensitive to aspects; can influence which receptors are active, due to relative amounts of different components of the odorant

30
Q

Because we rarely smell pure odorants, we smell mixtures; how do we process the components

A

Analysis and synthesis

31
Q

Analysis

A

Separate into parts

32
Q

Synthesis

A

Combine into a new whole

33
Q

Binaral rivalry

A

Competition between the two nostrils for odor perception; when a differen scent is presented to each nostril, we experience one scent at a time, not a combination of the two scents together

34
Q

What we smell can affect what we

A

See

35
Q

Adaptation

A

Sense of smell is a change detector; allows for responses to new smells and/or important information

36
Q

Bottom up receptor adaptation

A

Receptors stop responding to the odorant and detection stops; firing rate

37
Q

Top down influence of adaptation

A

Conscious thought can influence time course of adaptation

38
Q

Negative bias of smell makes it

A

Stronger for longer, more important

39
Q

Positive bias to a smell makes it

A

Decrease over time more than the neutral smell

40
Q

Odor hedonics

A

The liking dimension of odor perception, typically measured with scales pertaining to an odorants perceive pleasantness, familiarity and intensity

41
Q

Familiarity of smells

A

We like odors that we have smelled before

42
Q

Intensity of smells

A

Good smells: neutral for less intense smells, unpleasant for very intense
Bad smells: dislike increases the more intense the smell gets

43
Q

Hedonic responds are most likely from nurture

A

Odor preferences of infants vary from adults, cross cultural data supports associative learning

44
Q

2 aspects to support nature of hedonics

A

Pain response to irritating odors and variability in receptor types and amounts

45
Q

Sniffing sticks

A

Pre-determined set of odorant sin distinct performance for discrimination

46
Q

Triangle test

A

Participant is given 3 odors to smell, two are the same and 1 is different; identity the odd odor; used for detection and discrimination