• Stimuli (chemical) → • Binding to cell surface/intracellular taste receptor proteins → • Change in balance of ions across the cell surface membrane → • Cell depolarization → • Receptor cell release neurotransmitter → • Depolarization of the innervating nerve → • Generation of action potential → • Message is conveyed → • Message is decoded to the primary gustatory cortex

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4 distinct taste

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Elicited by protons

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protons may have a local effect on oral soft and hard tissue

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acidity indicates spoiled food

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5 receptors for sour taste EMHHA

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Mechanisms of salivation and gustation are tightly linked – sour is the strongest

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Salivary flow rate increase = higher level of

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strong contraction of facial muscles will channel saliva to tongue thus help to neutralize the protons

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'2' Most important ion for stimulation:

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ENaC allows for sodium influx, detection of chloride mediated by paracellular transport

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ENaC is less prominent, unidentified mechanism in ? salty taste

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Associated with high-calorie foods

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3 Receptors for sweet taste GTT

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Receptors are expressed in about how many percent? of taste cells located in the posterior, lateral, and anterior taste buds for the tongue

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allows transduction of taste elicited by many bitter compounds

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- Detection of potentially harmful, toxic compounds - Taste evoked by simple ions (K+), complex artificial (denatonium) or naturally-occurring compounds (caffeine, strychnine, quinine) - Threshold is lowest of all the taste qualities - Mechanism or transduction is most diverse

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- Taste evoked by simple ions (K+), complex artificial (denatonium) or naturally-occurring compounds (caffeine, strychnine, quinine) - Threshold is lowest of all the taste qualities - Mechanism or transduction is most diverse

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Mechanism or transduction is most diverse

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a candidate sweet receptor

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cloned and found to be functional only in presence of another taste receptor

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heterodimer

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(α subunit) activates one or more phosphodiesterases, reducing levels of cyclic nucleotides (cAMP and cGMP) leading to opening of a cyclic nucleotide-gated cation channel and cell depolarizatio

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2 Receptor for bitter taste

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50 to 80 membrane associated bitter taste receptors; assumed but not verifies that they are bitter responsive

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ano japanese word ng umami

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- A taste quality specific for monosodium glutamate (vetsin) - Glutamate (excitatory neurotransmitter) and MSG are almost identical

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o signal transduction is assumed to be similar that located in the brain o problem: generally inhibitory

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o Recent receptor proposed o Similar to proposed sweet receptor except one monomer of dimer pair is different (T1R1 is T1R2 for sweet taste) o Its response to glutamate is enhanced by ribonucleotides (synergism)

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2 Receptors for umami taste

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- Taste receptors - Goblet-shaped epithelial cells with small pore opening to the mucosal surface - Lemon-shaped - Measure about 70μ in length and 40μ in diameter - Approximately 10,000 buds in man - Comprise of 20-60 cells - Has no blood or lymphatic vessels; but both adrenergic and cholinergic nerve fibers have been found in taste buds

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ilan taste buds naten

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ilang cell taste buds

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globular, fungiform and palatal – long and slender

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shape of taste buds

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taste buds measurement in length and diameter (MICRONS YAN HA)

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respond to a low concentration for both sweet and salty taste substance

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respond to a low concentration of sweet substance and high concentration of salty, sour and bitter stimuli

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respond to a sour, bitter substance with higher concentration on salty and sweet

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'3' The greatest number of taste buds in the oral cavity - respond to

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type 1

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type 2

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type 3

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'2' serves as neurotransmitter

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serves as receptor cells

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there is decrease in the intensity or sensation or disappearance of sensation even with continuous stimulation of receptors

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will stay (adapted to the taste)

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– the taste of the cheese still linger (even after swallowing)

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eats sweets then sour (sour intensifies)

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one side of the tongue can taste the sugar on the other side of the tongue

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