neurobio 914 ch 8 of Bear's book: the chemical senses part 2 (taste, umami, bitter, sweet, smell, T2
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what is the role of supporting cells in the olfactory epithelium?
they are similar to glia. Among other things, they help produce mucus.
what is the role of basal cells in the olfactory epithelium?
they are the source of new receptor cells
what is the cribriform plate?
a thin sheet of bone through which small clusters of exons penetrate, coursing to the olfactory bulb.
how large is the number of odorant receptors?
very large, over 1000 diff receptors in rats
each olfactory receptor cell contains typically expresses how much of the thousands of types of receptor genes?
how do the 1000 diff odorant receptors able to distinguish between tens of thousands of smells?
like the sense of taste, the sense of smell has a popilation coded scheme
the input layer of each olfactory bulb contains about 2000 spherical structures called _______
true or false, olfactory information is only encoded in which olfactory receptor cells generate an action potential
false, the temporal coding (how often an action potential fires) also encodes the olfactory info.
what is a sensory map?
a sensory map is an orderly arrangement of neurons that correlates with certain features of the environment. For example, neurons in a specific pace in the olfactory bulb respond to particular odors. Consequently, the smell of a particular chemical is converted into a location on a map within the neural space of the olfactory bulb.
what is unusual about the olfactory projections to the cortex?
other sensory systems pass through the thalamus before projecting to cortex, but some olfactory connections to cortex are direct
olfactory receptor cells are mapped onto the dnendrites in the glomeruli of the olfactory bulbs in what manner of organization?
the mapping of receptor cells onto glomeruli is remarkably precise. Each glomerulus receives receptor axons from a large region of the olfactory epitheliu, but from only one type of receptor. This means that the array of glomeruli within a bulb is a very orderly map of the receptor genes expressed in the olfactory epithelium and a map of odor information.
what i sthe function of cAMP in olfactory transduction?
activates cAMP-gated cation chanels
What is receptor potential?
the receptor potential is a change in membrane potential in a receptor in respone to an appropriate stimulus; it is not an action potential. For example, when an appropriate chemical stimulates a taste receptor, its membrane potential changes, usually by depolarizing. This voltage shift is called the receptor potential. If the receptor potential is depolarizing and large enough, most taste cells, like neurons, may fire an action potential
threshold concentration is the critical concentration at which a taste stimulus evokes a perception of taste. How do the papillae respond when the stimulus concentration is just above the threshold value?
when concentration of a taste stimulus is just above the threshold, ie, a weak stimulus the papillae are sensitive to just one basic taste. But when the concentrations of taste stimuli are well above threshold, most papillae become less selective, responding to two basic tastes instead of one.