Chapter 15: Olfaction and Taste Flashcards
(114 cards)
1
Q
Olfaction
A
sense of smell, ability to detect odors
2
Q
Gustation
A
sense of taste
3
Q
What are the two senses that are considered chemical senses because their role is to detect chemicals in the environment?
A
olfaction and gustation
4
Q
______ are the perceptual experiences that derive from the detection of odorants, which are airborne chemical molecules
A
Odors
5
Q
Sense of smell is an early warning system- allows us to detect potentially harmful or helpful substances before we come into direct contact with them. T/F
A
True
6
Q
The nose is composed of…
A
two nostrils, nasal septum (that consists of cartilage and separates nostrils)
7
Q
Is there a need for integration of information across nostrils?
A
No because nostrils sample the same air.
It is not like the visual system.
8
Q
Inside the nasal cavity we can find _________, which are body knots of tissue that help air project up to the olfactory cleft.
A
turbinates
9
Q
7
A
10
Q
Olfactory Epithelium contains:
A
– Olfactory Receptor Neurons
– Basal Cells
– Supporting Cells
11
Q
Where are the olfactory receptor neruons located?
A
in olfactory epithelium
12
Q
What do the olfactory receptor neurons do?
A
- Transduce chemical to neural signal
- Just a couple of centimeters behind
the eye - Only last about a month
- Have cilia that contain the
transduction elements on their tips - Chemical triggers cilia, causing neural
signals to begin - 20 million olfactory receptors neurons
in the nose - 350 different kinds of olfactory
receptor neuron
– Each responds to different
odorants
13
Q
_____________ create olfactory receptor neurons and are located in the olfactory epithelium.
A
Basal cells
14
Q
_____________ provide metabilic supplies to olfactory receptor neurons and are located in the olfactory epithelium.
A
Supporting cells
15
Q
_______________ are species that are heavily dependent on olfactory system.
A
Macrosomatic
- Many more olfactory
receptor neurons than
humans
– Can detect smells miles
away
16
Q
Humans are macrosomatic. T/F
A
False, they are microsomatic because they rely on other senses more than smell
17
Q
Odors:
A
the perceptual experience of odorants, which are airborne chemical stimuli
18
Q
Odorants:
A
molecules our olfactory system responds to when we detect them in the air
19
Q
Nasal septum:
A
the wall of cartilage that separates the nostrils
20
Q
Turbinates:
A
bony knots of tissue that serve to disperse air within the nasal cavity
21
Q
Olfactory cleft:
A
the channel at the back of the nasal cavity that funnels air up toward the olfactory epithelium
22
Q
Olfactory epithelium:
A
a mucous membrane inside each nostril of the nose that contains the receptor cells for the olfactory system
23
Q
Olfactory receptor neurons:
A
receptor cells located in the olfactory epithelium that detect specific chemicals in the air and transduce them into a neural signal
24
Q
Supporting cells:
A
cells that provide metabolic supplies to the olfactory receptor neurons
25
Basal cells:
cells that create olfactory receptor neurons
26
Macrosmatic:
species that are heavily dependent on their olfactory system
27
17
28
Trigeminal nerve
Transmits information
about the feel of an
odorant
29
18
30
Olfactory receptor neurons project their axons through little holes in the base of the skull called _________________
cribriform plate
* Separates nose from the brain
* Very susceptible to injury
* If fractured, could sever axons from olfactory receptors
31
What's the difference between the sense of smell and other senses?
there is no comparison
information goes straight to the olfactory bulb, while other senses have to go through the thalamus
32
Anosmia
it is sometimes due to a fractured cribriform plate
severed olfactory recepetor axons
no smell info can get to brain
no sense of smell
33
Regeneration of olfactory nerves happen every...
month
34
23
35
What is the olfactory bulb?
it is part of the brain just behind the nose, and it is also the first place in the brain where olfactory information is processed
36
In the olfactory bulb, axons connect with spherical structures called _________.
glomeruli
* Two types of dendrite in
glomeruli
– Mitral Cell
– Tufted Cell
37
In the glomeruli that are in the olfactory bulb....
there is an odorant map
it is similarly structured odors go together
organized by chemical structure (not quality of smell per se)
38
The two types of cells in glomeruli respond to ___________ odorants.
different
the two types of cells in glomeruli are the mitral cell (can provide inhibition) and the tufted cell
39
29
40
What is the olfactory tract?
amygdala, entorhinal cortex, piriform cortex
41
Smell is important
in __________ and
__________.
memory; emotion
42
The olfactory tract to amygdala is where...
attention to emotional stimuli
identifying threat
connected to frontal lobe and hippocampus (encoding memory)
amygdala is a "nitrous boost"
43
The second location of the olfactory tract, the entorhinal cortex is...
in the temporal lobe
sends info to the hippocampus
memory area
44
The third location of the olfactory tract, the piriform cortex is...
in the temporal lobe
it is the primary olfactory cortex
45
The piriform cortex has an ___________ and _____________.
Anterior; posterior
46
What happens in the anterior piriform cortex?
* Representing chemical structures of odorants
* Creates a map of odorants by their chemical structures
* Each neuron responds to a small range of odorant molecules
47
What happens in the posterior piriform cortex?
* Represents an odor’s quality
* Subjective
* Smokey
* Christmas-y
* Fresh
48
What are some facts about hte orbitofrontal cortex?
* In prefrontal cortex (taking situation into account, decisions based off context)
* Receives projections from piriform cortex and limbic system
* Integrates olfaction and taste perception
* Establishes emotional nature of odors
* Affective value
* “feeling” we get when we smell an odor
49
How much odorant in the air to detect that odorant?
– Depends on the molecule
– Some require more/less
50
Are humans good at identifying odors?
Humans really terrible at
identifying a smell from memory!
* 40% correct
– Easier if they get multiple choice
51
Tip-of-the-nose phenomenon
– Odor feels familiar, but cant name it.
– Give them some options, and they can
– Disconnect between olfaction and
language
* Difficult to say name of odorant
– Esp. in unusual context
52
If we only had the anterior piriform cortex what would happen?
we won't have subjective understanding, where one would not label the quality and would not think of it in a higher level
53
Olfaction Imagery
– Imagining the odor from memory
– Humans are pretty terrible at this too!
– When they can do it, activity in piriform cortex
54
Olfaction Illusions:
1) Showing someone colorful vs not-colorful liquid changes their perception of the odor of the liquid
2) Giving different smells to each nostril
* Perceive one smell, then the other, not both at same time- nose is not set up for two different smells at once.
3) Label same chemical “cheese” vs “body odor”
* Different pleasantness ratings
* Different activity in piriform cortex
55
Microsmatic:
species that are less dependent on their olfactory system
56
Trigeminal nerve:
a nerve that is associated with the feel of odorants; also known as the fifth cranial nerve
57
Cribriform plate:
a perforated section of skull bone that separates the nose from the brain; axons from olfactory receptor neurons pass through to allow olfactory information to enter regions in the brain
58
Anosmia (smell blindness):
the inability to smell, usually caused by cribriform plate damage
59
Olfactory nerve (first cranial nerve):
the axons of the olfactory receptor neurons that leave the nose and enter the olfactory bulb
60
Olfactory bulb:
a part of the brain just behind the nose; it is the first place in the brain where olfactory information is processed
61
Glomeruli:
spherical structures within the olfactory bulb where the olfactory tract forms synapses with mitral cells and tufted cells
62
Mitral cells:
neurons that start in the glomeruli of the olfactory bulb and project to other areas of the brain; respond to different odorants than do tufted cells.
63
Tufted cells:
neurons that start in the glomeruli of the olfactory bulb and project to other areas of the brain; they respond to different odorants than do mitral cells
64
Olfactory tract:
the pathway leading from the olfactory bulb to other regions of the brain
65
Amygdala:
an area of the brain in the limbic system, associated with the experience of emotion, particularly fear
66
Entorhinal cortex:
an area in the medial temporal lobe, associated with a number of memory functions
67
Piriform cortex:
an area in the anterior region of the temporal lobe that receives input from the olfactory bulb and is involved in olfactory processing; often considered the primary olfactory cortex
68
Anterior piriform cortex:
a structure located in the front portion of the piriform cortex that is associated with representing the chemical structures of odorants
69
Posterior piriform cortex:
a structure located in the back portion of the piriform cortex that is associated with an odor’s quality, regardless of its chemical composition
70
Orbitofrontal cortex:
a part of the prefrontal cortex that appears to be critical in the emotional experience of odors and integrating olfaction and taste perception, among other functions
71
Tip-of-the-nose
phenomenon:
a phenomenon that occurs when a person is familiar with an odor but cannot recall its name, despite feeling as if he or she can
72
Tastants:
molecules recognized by taste receptors that induce responses in taste receptors on the tongue
73
33% of taste buds are on what three locations?
epiglottis, soft palate, and upper esophagus.
74
One the taste recpetors have detect the tastants, they then transmit neural signals to...
the brain
75
Taste:
the perception of the transduction of tastants along the surface of the tongue
76
Flavor:
the combined sensory experience of a food, which combines its taste, its odor, its effect on the trigeminal nerve, and even visual experience
total perceptual experience that occurs during eating
– Combines not only taste and olfaction but also somatosensory experience and visual experience.
77
We need situational cues to identify orders. T/F
T
without them it is hard since we depend on context, memory, etc. this is why we as humans are not good at identifying smells.
78
Taste buds:
small structures located along the surface of the tongue or mouth that contain the receptor cells
– Cluster of cells that resembles a garlic bulb
– Each taste bud contains 40-100 taste receptor cells
* Elongated neurons with “hair like” cells- microvilli or cilia at end
* Transduce tastants into neural signal
* Die off after about a week or two, replaced with new receptor cells
79
Describe the three types of cells or taste receptors. (*BOOK only has 2 types but there are 3)
* Type 1
– About half the cells in a bud (most prevalent)
– Glial-like functions (glial cells are support cells): do modulation type work
– Modulate signals from other cells
– Detects “sweet”, “Umami”
Type 2
– 1/3rd of the cells in the bud
– Larger than type 1
– Mostly activate for sugar, amino
acids and/or bitter stimuli
* Umami (proteins)
– G-protein cells (like a butler or second messenger)
– Most will focus on just one taste
* Sweet or bitter, not both
* Type 3
– Least numerous in bud
– Can detect sour taste
– % varies depending on location
* Fungiform may only have one type 3
cell!
* What receptor tastes “salty”?
– Simple sodium channel
– Probably more than one type of
receptor
80
Information leaves the taste buds through what cranial nerves?
the 7th, 9th, 10th cranial
nerves
81
After gustatory neural information has gone through the cranial nerves, it heads to the _______, then synapses in ___________, nucleus of the __________ tract, then travels to the __________, then to the _________.
brain; medulla; solitary; thalamus; cortex
82
When gustatory information arrives in the cortex, it enters the ________.
insula
83
Describe the insula.
– Anterior insular cortex
– In frontal lobe
– Sometimes called “gustatory cortex”
– Projects to orbitofrontal cortex
– When rats eat food – activity in insular cortex
* When rats eat food and they’re hungry, activity in insular cortex and
orbitofrontal cortex
* Orbitofrontal cortex- good “Feeling”
about eating?
It keeps us from disease
84
What is the cause of individual differences in taste perception?
– Genetic differences
* Gene for bitter foods
– Two forms- if you have one form, you can taste bitter foods easily, other form, less sensitive
» PAV: can detect bitter
» AVI: less sensitive to bitter
* Non-tasters
85
Describe the supertasters.
– PAV form of bitter taste gene
– More fungiform papillae
– Higher percentage in populations of non-European origins
– Higher percentage in females
– More recent data- fugiform papillae density does not predict super-tasting
* Perhaps people who are supertasters also have more fugiform papillae
* Having more fugiform papillae alone is not enough to be a super taster- some other factor (genes? PAV?)
86
Synsepalum dulcificum
miracle berry miraculin
* Causes sour foods to taste sweet
* Binds to sweet receptors
– Only activates them at an acidic ph level (when eating sour foods)
87
Where is the anterior insular cortex located?
In the frontal lobe
88
Papillae:
small structures that contain the taste buds
line the surface of tongue and mouth
– Contain Taste Buds (which hold receptor cells- more on that later)
89
What are the 4 types of papillae?
– Fungiform
– Foliate
– Circumvallate
– Filiform
90
Fungiform papillae:
located mostly along the edges and top of the tongue; they respond to all five basic tastes
* Fungiform derived from
latin name for
“mushroom”
* Dense vascularization (a lot of blood vessels) -
red in color
91
Foliate papillae:
found along the side of the tongue; they respond to all five basic tastes
* “A” in the image to the right (look at image in slide 11)
* Posterior, Along side of tongue
92
Circumvallate papillae:
found along the very back of the tongue in a virtual row; they respond to all five basic tastes
93
Filiform papillae:
found all over the tongue; they contain somatosensory receptors rather than taste buds, so that they feel food rather than taste it
* Fiium= latin for thread
* Allow soft substances to be licked into the mouth
– (ice cream!)
- No taste buds
94
Taste receptor cells:
cells within the taste bud that transduce tastants into a neural signal
95
Receptor cells:
taste receptor cells that transduce sweet tastes, umami tastes, and bitter tastes
96
Presynaptic cells:
taste receptor cells that transduce salty and sour tastes
97
Anterior insular cortex
(insula):
a part of the frontal lobe that serves as the primary taste cortex
98
Tasters:
people who can detect bitter compounds
99
Nontasters:
people who cannot detect bitter compounds except at very high concentrations
100
Supertasters:
people who are extremely sensitive to bitter tastes; they usually do not like foods with many bitter compounds
101
Phantosmia:
hallucinatory perception of odors
102
Ageusia:
loss of the ability to taste
103
Artificial sweeteners:
sugar substitutes that seek to duplicate the effect of sugar on our sense of taste, but with fewer calories
104
Which tastes alert us to foods with needed nutrients?
Sweet: Sugar! Carbs! Necessary for survival
Salty: Need sodium for multiple processes
Umami (savory): proteins
105
Which tastes alert us to potential danger?
Bitter
Sour
106
Odors are airborne chemical molecules. T/F
False
107
The most recently recognized flavor is ______.
umami
108
Olfactory receptor neurons are created by basal cells. T/F
True
109
The amygdala is an area of the brain associated with emotion. T/F
True
110
The olfactory bulb is located just below the nose. T/F
False
111
The human olfactory system can sense any chemical if it is airborne. T/F
False
112
The channel at the rear of the nasal cavity that diverts air into the olfactory epithelium is called the ______.
olfactory cleft
113
The small structures positioned on the outside of the tongue that hold receptor cells are known as ______.
taste buds
114
The ability to identify the presence of an odorant is known as ______.
detection
