Phys. of Olfaction and Gustation

Question 1

Loss of sense of smell

Answer 1

Anosmia

Question 2

Loss of sense of taste

Answer 2

Aguesia

Question 3

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

Answer 3

Tastants

Question 4

Chemical compounds that bind to odor receptors and impart odor

Answer 4

Odorants

Question 5

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

Answer 5

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

Question 6

Salty and sour tastants enter taste bud cells via?

Answer 6

Voltage gated ion channels

Question 7

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

Answer 7

G-protein coupled receptors

Question 8

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

Answer 8

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

Question 9

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

Answer 9

ATP

Question 10

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

Answer 10

Serotonin

Question 11

ORN

Answer 11

Odorant Receptor Neurons

Question 12

Olfactory cells are what type of neurons?

Answer 12

Bipolar

Question 13

What NT do Olfactory cell neurons release?

Answer 13

Glutamate

Question 14

What forms the olfactory mucosa?

Answer 14

Olfactory bipolar neurons AND Basal cells (supporting)

Question 15

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

Answer 15

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

Question 16

Describe the process for depolarizing an ORN

Answer 16

• 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

Question 17

ORN adaptation?

Answer 17

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

Question 18

What are the 3 mechanisms for ORN adaptation?

Answer 18

• 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

Question 19

What is bitter taste thought to guard against ingesting?

Answer 19

Toxins/poisons

Question 20

Describe bitter-tuned GPCRs

Answer 20

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

Question 21

Sweet tastants signal?

Answer 21

Presence of carbs - energy source

Question 22

Salty tastants signal?

Answer 22

Intake of sodium essential for maintaining water balance in body

Question 23

Umami tastants signal?

Answer 23

A food’s protein content due to amino acids

Question 24

Sour tastants signal?

Answer 24

Presence of dietary acids

Question 25

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

Answer 25

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

Question 26

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

Answer 26

Decreased nasal mucus production and receptors of ORNs decrease

Question 27

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

Answer 27

Meds, diseases, smoking, pollutants

Question 28

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

Answer 28

- 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

Question 29

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

Answer 29

Childhood | Utero

Question 30

Describe the effects of sweet tastes on newborns

Answer 30

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

Question 31

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

Answer 31

Sucrose

Question 32

Major mechanism behind the newborn-sweet solution effect?

Answer 32

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

Question 33

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

Answer 33

Unknown

Question 34

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

Answer 34

Sodium salts and/OR sugars

Question 35

At what level do sodium salts mask the bitter taste?

Answer 35

At the bitter-receptor level

Question 36

At what level do sugars suppress the bitter taste?

Answer 36

At the cognitive level

Question 37

What makes up the physiologic gustatory cortex?

Answer 37

Postcentral gyrus, Frontal operculum, Insula

Question 38

The perception of flavor requires what?

Answer 38

Gustatory cortex, olfactory cortex and somatosensory cortex

Question 39

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

Answer 39

Orbitofrontal cortex

Question 40

What CNs contribute taste?

Answer 40

CN VII, IX, X

Question 41

Describe the pathway for gustation

Answer 41

- 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

Question 42

Relay station for taste perception

Answer 42

VPM of thalamus

Question 43

Discriminative aspects of taste

Answer 43

Gustatory cortex

Question 44

Affective aspects, emotional aspects and memories of eating

Answer 44

Amygdala

Question 45

Integrates homeostatic mechanisms of eating

Answer 45

Hypothalamus

Question 46

Interplay between eating and calming effects

Answer 46

Limbic system

Question 47

Basis for salivating, mimetic responses and swallowing

Answer 47

Medullary reflex arcs in the nucleus tractus solitarius

Question 48

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

Answer 48

1 glomerulus where ORNs synapse and release glutamate

Question 49

Glomerulus ascends to what type of cell?

Answer 49

Mitral cells in the olfactory bulb

Question 50

What does the olfactory tract NOT relay through?

Answer 50

Thalamus

Question 51

4 main regions of the olfactory cortex?

Answer 51

Piriform cortex Anterior cortical amygdaloid nucleus Periamygdaloid cortex Entorhinal cortex

Question 52

What are the jobs of the piriform cortex?

Answer 52

Control of appetite and integration of taste, sight and smell

Question 53

What is the job of the anterior cortical amygdaloid nucleus?

Answer 53

Emotional learning and olfactory fear conditioning

Question 54

What is the job of the periamygdaloid cortex?

Answer 54

Emotional aspect elicited by odor

Question 55

What is the job of the entorhinal cortex?

Answer 55

Important in memory formation and recall upon odor sensation

Question 56

Where does the entorhinal cortex project?

Answer 56

Hippocampus

Question 57

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

Answer 57

Reversible Hyposmia

Question 58

Increased sense of smell

Answer 58

Hyperosmia

Question 59

Where has hyperosmia been seen?

Answer 59

With migraines, pregnant women and psychotic states

Question 60

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

Answer 60

Olfactory bulb and the dentate gyrus of hippocampus

Question 61

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

Answer 61

Parkinson's disease - often before motor deficits occur

Question 62

Responsible for appreciating all aspects of food

Answer 62

Orbitofrontal cortex