neurobio 913 ch 8 of Bear's book: the chemical senses part 2 (taste umami bitter sweet smell T2

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  1. true or false, the tip of the tongue is most sensitive to sweetness?
  2. what are the three types of papillae?
    foliate papillae, vallate papillae, and fungiform papillae
  3. each papilla has several hundred ___ ____
    taste buds
  4. true or false, anions affect the taste of cations in salty taste?
  5. bitter substances are detected by how many different types of T2R receptors?
    about 30
  6. humans have difficulty telling apart different bitter tastants. Why?
    probably because each bitter taste cell expresses many, and perhaps all, of the 30 bitter receptor proteins. Because each taste cell can send only one type of signal to its afferent nerve, a chemical that can bind to one of its 30 bitter receptors will triger essentially the same response as a different chemical that binds to another of its bitter receptors
  7. true or false. ALL sweet tastants are detected by the same taste receptor protein
  8. true or false. Bitter taste receptors are made up of two subunits
    false. one subunit
  9. true or false. each primary taste axon receives info from only one taste receptor
    false. there is convergence of receptor cell input onto afferent axons. Each receptor cell synapses onto a primary taste axon that also receives input from several other receptors.
  10. what occurs in olfactory cells once the cation-selective cAMP gated channels open?
    current flows inward and the membrane of the olfactory neuron depolarizes. Besides Na, the cAMP gated channel allows substantial amounts of Ca to enter the cilia. In turn the Ca triggers a Ca activated chloride current that may amplify the olfactory receptor potential. (this is a switch from the usual effect of Cl currents, which inhibit neurons; in olfactory cells, the internal Cl concentration must be unusually high so that a Cl current tends to depolarize rather than hyperpolarize the membrane)
  11. what is it called when the strength of an odor decreases even when the odorant is still present?
  12. true or false. Receptor cells carrying the same type of receptor send their nerve processes to the same glomerulus.
  13. describe the intracellular transduction pathway involved in olfactory cells
    odorant binds to membrane odorant receptor proteins. g protein is stimulated which then activates adenylyl cyclase. AC forms cAMP, which bind to cAMP-specific cation channels. Opening of the cation channels results in influx of Na and Ca, which leads to depolarizaiton. The Ca then opens Ca-activated chloride channels, which leads to further depolarization
  14. what are vomeronasal receptors and what is their function?
    vomeronasal receptors express their own set of receptor proteins, which are similar to odorant receptors. There are much fewer vomeronasa receptor proteins than odorant receptor proteins. The types of chemicals vomeronasal receptors detect are largely unknown but it is likely that some of them are pheromones
  15. how do the 1000 types of receptor cells used discriminate among tens of thousands of odors?
    olfaction involves a population coding scheme. Each receptor protein binds different odorants more or less readily, so its receptor cell is more or less sensitive to those odorants. Some cells are more sensitive to the chemical structure of the odorants they will respond to than other cells are, but in general each receptor is quite broadly tuned.
  16. what is the composition of a taste bud?
    taste receptor cells, basal cells, and gustatory afferent axons

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neurobio 913 ch 8 of Bear's book: the chemical senses part 2 (taste umami bitter sweet smell T2
2014-03-30 12:40:56
neurobio 913 Bear book chemical senses part taste umami bitter sweet smell T2Rs pheromones olfactory epithelium
neurobio 913 ch 8 of Bear's book: the chemical senses part 2 (taste, umami, bitter, sweet, smell, T2Rs, pheromones, olfactory epithelium)
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