How many basic tastes are there?
Six, possibly. Umami, salty, bitter, sour, sweet, fat.
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What receptors do sweet tastes transuce through
T1R2+T1R3, Possibly others
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What receptors do salty tastes transuce through
ENac receptors
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What receptors do bitter tastes transuce through
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What receptors do umami tastes transduce through?
T1R1 + T1R3, mGluRs
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What receptors do fat tastes transuce through
GPR120, GPR40, CD36, Kch
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What modalities are combined for a full sense of taste?
Smell, texture, temperature and taste
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What do we use to taste?
Tongue, palate, pharynx, epiglottis.
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The three types of papillae. Draw a tongue and label it.
Fungiform, filliform, circumvallate papillae, foilate papillae
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Relationship between papillae and taste receptor cells
Each papillae has 1-100 taste buds. Each taste bud has 50-100 taste receptor cells.
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Draw a taste receptor cell
microvilli, taste pore, taste cells, basal cells, gustatory afferents.
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What is the threshold concentration
The concentration where a single papilla will evoke a sense of taste in response to a purely sweet/sour stimuli.
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Are papillae selective for one taste?
At low concentrations, not at high.
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What is the chemically selective part of the taste receptor cell?
A small membrane region called the apical end
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What is the apical end like?
It has small microvilli that project into the taste pore, where it exposed to the contents of the mouth
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What is the life cycle of a taste cell?
Two weeks
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Are taste cells neurons? What makes them like neurons?
They aren't, but they form synapses, both with the gustatory afferents and the basal cells
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What happens when a taste cell is activated by an appropriate chemical?
it's membrane potential changes, by depolarising. It undergoes a voltage shift called the receptor potiential.
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Taste transduction: Salt. Give an overview
Na+ acts on amiloride sensitive calcium channels, causing depolarisation. Depolarisation -> VGNaC and VGCCs to open. ATP is released onto the gustatory afferent
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How is the amiloride sensitive Na+ channel different to the VGCC
It's voltage independent and it stays open all the time.
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Hydrogen ions enter through amiloride sensative na channels. They also block K+ channels
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Bitterness. What receptor?
T2R which is GPCR.
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Bitterness- what does the GPCR activate.
PLCB2 which activates IP3 which causes a rise in intracellular calcium.
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What does the rise in calcium do
TRPM5 opens and lets sodium in, same with VGSCs. this causes depolarisation and ATP is released
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What are the receptors for sweet and umami tastants? Then, how is the pathway different to bitterness?
Sweet - T1R2, T1R3. Umami - T1R1/T1R3
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Where is the main flow of taste information from the taste buds?
To the thalamus, then to the cerebral cortex
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Cranial nerves and gustation
The anterior two-thirds of the tongue and the palate send axons into a branch of the facial nerve. the posterior third is innervated by the glossopharangeal nerve. Throat, epiglottis and pharynx - vagus nerve
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Where do the axons synapse?
The gustatory nucleus, part of the solitary nucleus in the medulla
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The path diverges - Explain the path to the neocortex via the thalamus
neurons of the gustatory nucleus synapse on a subset of small neurons in the VPM. The VPM sends axons to the primary gustatory cortex.
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Where is the primary gustatory cortex?
Brodmann's area 36, near the insula cortex.
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What can lesions in the VMP or the gustatory cortex cause
ageusia - loss of taste perception
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What two features allow recognition of taste
roughly labelled lines and population coding - incl. smell, texture.
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Card 2


What receptors do sweet tastes transuce through


T1R2+T1R3, Possibly others

Card 3


What receptors do salty tastes transuce through


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Card 4


What receptors do bitter tastes transuce through


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Card 5


What receptors do umami tastes transduce through?


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