Taste Flashcards
The Chemical Senses
The general chemical sense is transduced by:
Taste is primarily transduced by receptor cells within taste buds on the tongue.
These cells express a family of receptor proteins that bind families of molecules representing the standard taste categories: salt, bitter, sweet, sour and umami (glutamate).
The general chemical sense is transduced by unmyelinated somatosensory afferents present in the mouth.
Ex: Capsaicin (hot pepper ingredient). Activating these receptors on the skin would lead to a sensation of pain and heat. Activating them on the tongue leads to the sensation of “hot peppers” and is interpreted as a taste.
SARS-CoV-2 appears to be able to infect ___ cells of the ___, leading to ____ loss of taste than can be explained by loss of ___ alone
SARS-CoV-2 appears to be able to infect supporting cells of the tastebuds, leading to more loss of taste than can be explained by loss of smell alone
Types of Papillae
Mean number of taste buds = ____
Papillae create:
Mean number of taste buds = 4000
Papillae create trenches where tastants can be concentrated.
role of taste calls in avoiding or approaching food
Salty: Safe (approach) Sour: Acidi; unripe/poor nutritional value (avoid) Sweet: Nutritious (approach) Bitter: Poisonous (avoid) Umami:
Cranial Nerve VII:
Cranial Nerve IX:
Cranial Nerve X:
Cranial Nerve VII: Facial
Cranial Nerve IX: Glossopharyngeal
Cranial Nerve X: Vagus
Transduction of Taste
salty
Salty: sodium ions cross microvillus wall at specialized sites -> depolarizes cell -> action potentials generated
- transduced by a sodium channel
- influx of sodium ion
- amiloride sensitive channel
- leads to depolarization due to positive ion influx
T1R3:
T1R3: responsible for making artificial sweeteners taste “sweet”
General Sensitivity Rule-of-thumb:
General Sensitivity Rule-of-thumb:
Bitter > Sour, Salty, Sweet > Umami
Temperature vs. Sensitivity
Overall, therefore, as temperature rises, perceptions of sweetness and bitterness tend to intensify, and perceptions of sourness and saltiness tend to remain the same.
Because the effect of temperature is not uniform across compounds, it can be expected that the taste “profile” of a food will change as its temperature changes.
Cranial Nerves- Central Connections
*Cranial Nerve VII (Facial): anterior 2/3 of tongue
Central connection: nucleus solitarius (solitary nucleus)
*Cranial Nerve IX (Glossopharyngeal): posterior 1/3 of tongue
Central connection: Inferior glossopharyngeal ganglion and nucleus solitarius (solitary nucleus)
*Cranial Nerve X (Vagus): palate, epiglottis
Central connection: nucleus solitarius (solitary nucleus)
Jellybean test:
Jellybean test:
There are two jellybeans- one strawberry and one cherry
With your eyes closed and nose pinched, you will probably just guess that they are jellybeans
With your eyes open and nose pinched, you will probably narrow down your guess to some type of red fruit flavored jelly bean, but you are unlikely able to determine them to be “strawberry” and “cherry” unless you un-pinch your nose.
amygdala and taste
taste aversion
To induce conditioned taste aversions in the lab:
To induce conditioned taste aversions in the lab: apply an illness-inducing injection of lithium chloride after ingestion of a flavored solution.
T/F food can be rewarding regardless of taste
TRUE
food can be rewarding regardless of taste
***Where do the cranial nerves carrying taste information synapse in the medulla?
Solitary nucleus
**Where do the axons from the medulla (solitary nucleus) go?
VPM
the Frontal Cortex Integration of Flavor is the ?
Orbitofrontal Cortex (Frontal Cortex Integration of Flavor)
taste buds
-location
Onion-shaped structures in the mouth and pharynx that contain taste cells.
location of salty:
Towards tip to first test for nutrient content
Transduction of Taste: sour
Sour: H+ ions bind to receptor sites -> inhibit K+ pumps -> cell depolarizes and generates neural “spikes”. Corresponds to acidic strength (i.e., pH)
- influx of hydrogen ions
- TRP channel
- leads to depolarization due to positive ion influx
Transduction of Taste: the rest besides sour and salty
Sweet, Bitter, and Umami: all work through GPCRs
Ligand binds receptor -> PLC -> IP3 -> calcium fluxes in -> cell depolarizes ->action potentials
Where does the VPM send axons?
• Taste information is then relayed to the insular cortex
Orbitofrontal Cortex
-function
*Putting together things like the sight and smell of food
hypothalamus and eating
The hypothalamus knows all that goes on in your body.
It is also responsible for your feeding behaviors, so it really needs to know about what you are eating.
There is some evidence suggesting that the nervous system also reads the nutritional value of your food. This would likely require hypothalamic involvement.
Eating a bland diet –>
Eating a bland diet –>increased cravings for tasteful foods, even if nutritional needs have been met
• Sometimes called the secondary taste cortex
Orbitofrontal Cortex (Frontal Cortex Integration of Flavor)
T/F Motivational states (e.g., hunger) affect the sensitivity of cells in the insular cortex
FALSE Motivational states (e.g., hunger) do not affect the sensitivity of cells in the primary (insular) cortex.
Do motivational states (e.g., hunger) affect the sensitivity of cells in the insular cortex and/or the orbitofrontal cortex?
orbitofrontal cortex only
-motivational, emotional and learning experiences heavily influence the sensitivities of cells in the orbitofrontal cortex.
T/F regional variations in threshold/sensitivity in regards to taste buds that contains taste cells
TRUE
What do the 5 types of tastants tell us about the food? ***
2.5) What do the 5 types of tastants tell us about the food?
Sensory Coding
•Intensity: increases in stimulus concentration leads to increased firing of taste cell (depends on concentration)
