chapter 11
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20 terms
Terms | Definitions |
|---|---|
 types of taste receptors | vallate, foliate, fungiform |
| vallate | 8-9 papillae, 250 taste buds each |
| foliate | 20 each side, 100-150 taste buds each side |
| fungiform | 200-300, 3-5 taste buds eacg |
| innervation of taste receptors | CN VII-anterior 2/3, CN IX-posterior 1/3, X-epiglottis to nucleus of solitary tract |
| structure of taste bud | taste pore, live 1-2 weeks, replaced by differentiation of basal cells |
| salty taste | Na+ influx |
| bitter taste | metabotropic or ionotropic, g-protein |
| sour taste | H+ influx or blocked K+ |
| sweet taste | g-protein, cAMP, just metabotropic |
| taste transduction mechanism | tastant molecule causes local EPSP, increased intracellular Ca++ causes NT vesicles to be released onto gustatory nerve, EPSP causes voltage-gated CA++ channels to open, some tastants cause release of CA++ from intracellular stores |
| central gustatory pathway | solitary n and tract to VPM of thalamus to gustatory cortex |
| olfactory epithelium | lateral wall of nasal cavity, roof of cavity, patch on nasal septum, 5 cm sq, several mil neurons, cell extends from mucosal membrane, through cribriform plate, into CNS |
| taste receptors | modified epithelial cells, not neurons, produce receptor potentials in response to tastant, have chemical synapses on peripheral endings of gustatory nerves |
| olfactory receptor | neuron, 30-60 day lifespan, replaced from basal cell pop., bipolar, cilia for odor detection |
| types of odorant receptors | can distinguish thousands of odors at low conc., 5000-10,000 dif. odors, >1000 types of receptors, each neuron expresses one type of receptor, rodents have 4 epithelial zones |
| olfactory signal transduction | G-protein coupled response, influx Ca++, NA+, causes EPSP which summates in cell body leading to action potential down axon |
| adaptation | 7 seconds |
| olfactory bulb | glomeruli-discrete synaptic units, neuron axon synapses on mitral relay neurons, tufted relay neurons, periglomerular interneurons (granule cells), glomerulus processes only one type of stimulus, many axons converge on each glom., 20-50 relay neurons leave each glom., primary axon from each relay neuron leaves only one glom., only sensory pathway that bypasses thalamus relay |
| pheromones | vomeronasal organ small/rudimentary in humans, important for seasonal breeding and other animals |
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