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Neuroendocrine > Phys. of Olfaction and Gustation > Flashcards

Phys. of Olfaction and Gustation Flashcards

1
Q

Loss of sense of smell

A

Anosmia

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2
Q

Loss of sense of taste

A

Aguesia

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3
Q

Chemical compounds that bind to taste receptors and impart the primary flavor categories

A

Tastants

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4
Q

Chemical compounds that bind to odor receptors and impart odor

A

Odorants

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5
Q

List some things on the apical domain of the taste bud cells

A

Microvili, Tastant receptors, Voltage gated ion channels, TRP receptors

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6
Q

Salty and sour tastants enter taste bud cells via?

A

Voltage gated ion channels

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7
Q

Bitter, sweet and umami tastants activate taste bud cells via?

A

G-protein coupled receptors

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8
Q

Once tastants bind/enter the taste bud cells, then what happens?

A

The cell becomes depolarized with an influx of Na/Ca+ and then the cell releases its NTs which causes an AP to be sent to the brain

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9
Q

What is the taste bud cell released NT for sweet, bitter and umami tastants?

A

ATP

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10
Q

What is the taste bud cell released NT for salty and sour tastants?

A

Serotonin

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11
Q

ORN

A

Odorant Receptor Neurons

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12
Q

Olfactory cells are what type of neurons?

A

Bipolar

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13
Q

What NT do Olfactory cell neurons release?

A

Glutamate

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14
Q

What forms the olfactory mucosa?

A

Olfactory bipolar neurons AND Basal cells (supporting)

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15
Q

Since humans only have 350 odorant receptors, what can change the smell?

A

Stimulation of different receptors, combinations of receptors and concentrations of the odorant

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16
Q

Describe the process for depolarizing an ORN

A
  • Odorant binds receptor and activates G protein (Golf)
  • Golf activates Adenylate Cyclase to increase CAMP
  • CAMP binds a Cyclic nucleotide Gated channel (CNGC) and allows Na/Ca to enter the cell
  • Ca+ binds a Ca gated Cl- channel and allows chloride to leave the cell
  • Further, more sodium enters using an exchanger
  • Cell is more positive and thus depolarized and the AP can propagate down the ORN
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17
Q

ORN adaptation?

A

Getting used to a smell to where you no longer notice it

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18
Q

What are the 3 mechanisms for ORN adaptation?

A
  • Enzymatic break down of cAMP = no cell depolarization
  • Reduced affinity of the CNGC to cAMP reduces cation influx
  • Odorant receptor becomes phosphorylated and less sensitive to odorants
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19
Q

What is bitter taste thought to guard against ingesting?

A

Toxins/poisons

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20
Q

Describe bitter-tuned GPCRs

A

They bind their ligand with very HIGH affinity compared to other taste receptors = can detect poisons at a very low concentration

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21
Q

Sweet tastants signal?

A

Presence of carbs - energy source

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22
Q

Salty tastants signal?

A

Intake of sodium essential for maintaining water balance in body

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23
Q

Umami tastants signal?

A

A food’s protein content due to amino acids

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24
Q

Sour tastants signal?

A

Presence of dietary acids

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25
Q

Usually over age 60, what happens to the gustatory system?

A

Decrease in taste bud number and remaining buds decrease in size - decreased sensitivity

26
Q

Usually over age 70, what happens to the olfactory system?

A

Decreased nasal mucus production and receptors of ORNs decrease

27
Q

What are some exogenous causes for decreased sensitivity in the gustation and olfactory systems?

A

Meds, diseases, smoking, pollutants

28
Q

As a a result of age-related sensitivity decreases in the olfactory and gustation systems, what happens?

A
  • Adults may add more salt and spice to their foods which can be a health concern for hypertension, etc.
  • Loss of taste and smell can also result in malnutrition, impaired immunity and deterioration
29
Q

Sensitivity to gustatory and olfactory cues are higher in ______ and start in ______

A

Childhood

Utero

30
Q

Describe the effects of sweet tastes on newborns

A

Small amounts of sweet solution placed on tongue of crying newborn exerts a rapid, calming effect along with a decreased HR that can persist for a few minutes

31
Q

What sweet solution is used in hospitals to give to newborns for minor procedures such as a blood draw?

A

Sucrose

32
Q

Major mechanism behind the newborn-sweet solution effect?

A

Sweet taste induced beta-endorphin release, activating the endogenous opioid system (anti-nociceptive)

33
Q

What is the cause for age-related decline in preference for sweetness?

A

Unknown

34
Q

Many pharmaceutical ingredients taste unpleasant, what are 2 things that can suppress/mask their taste?

A

Sodium salts and/OR sugars

35
Q

At what level do sodium salts mask the bitter taste?

A

At the bitter-receptor level

36
Q

At what level do sugars suppress the bitter taste?

A

At the cognitive level

37
Q

What makes up the physiologic gustatory cortex?

A

Postcentral gyrus, Frontal operculum, Insula

38
Q

The perception of flavor requires what?

A

Gustatory cortex, olfactory cortex and somatosensory cortex

39
Q

Where are all the inputs for perceiving flavor coming together and being integrated?

A

Orbitofrontal cortex

40
Q

What CNs contribute taste?

A

CN VII, IX, X

41
Q

Describe the pathway for gustation

A
  • CN VII, IX, X go to the nucleus tractus solitarius
  • From there the signal is relayed to the VPM of the thalamus
  • Then on to the gustatory cortex
  • The gustatory cortex sends signals to the orbitofrontal cortex and to the amygdala
  • The amygdala and the hypothalamus interact with the nucleus tractus solitarius
42
Q

Relay station for taste perception

A

VPM of thalamus

43
Q

Discriminative aspects of taste

A

Gustatory cortex

44
Q

Affective aspects, emotional aspects and memories of eating

A

Amygdala

45
Q

Integrates homeostatic mechanisms of eating

A

Hypothalamus

46
Q

Interplay between eating and calming effects

A

Limbic system

47
Q

Basis for salivating, mimetic responses and swallowing

A

Medullary reflex arcs in the nucleus tractus solitarius

48
Q

Olfactory neurons that express the same odorant receptors are then collected into?

A

1 glomerulus where ORNs synapse and release glutamate

49
Q

Glomerulus ascends to what type of cell?

A

Mitral cells in the olfactory bulb

50
Q

What does the olfactory tract NOT relay through?

A

Thalamus

51
Q

4 main regions of the olfactory cortex?

A

Piriform cortex
Anterior cortical amygdaloid nucleus
Periamygdaloid cortex
Entorhinal cortex

52
Q

What are the jobs of the piriform cortex?

A

Control of appetite and integration of taste, sight and smell

53
Q

What is the job of the anterior cortical amygdaloid nucleus?

A

Emotional learning and olfactory fear conditioning

54
Q

What is the job of the periamygdaloid cortex?

A

Emotional aspect elicited by odor

55
Q

What is the job of the entorhinal cortex?

A

Important in memory formation and recall upon odor sensation

56
Q

Where does the entorhinal cortex project?

A

Hippocampus

57
Q

Loss of smell due to thickened mucus that blocks odorants from binding

A

Reversible Hyposmia

58
Q

Increased sense of smell

A

Hyperosmia

59
Q

Where has hyperosmia been seen?

A

With migraines, pregnant women and psychotic states

60
Q

Where are the 2 areas in the brain where neurons will reform (neurogenesis)?

A

Olfactory bulb and the dentate gyrus of hippocampus

61
Q

With what disease has olfactory neuron impairment (pathology) been seen?

A

Parkinson’s disease - often before motor deficits occur

62
Q

Responsible for appreciating all aspects of food

A

Orbitofrontal cortex

Neuroendocrine (47 decks)

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