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5 Cards in this Set
- Front
- Back
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basic structure of olfactory system |
-uses only GPCRs (391 are expressed); alpha is Golf and activates AC III --> inc. cAMP -uses cAMP and ionic currents; result is AP -very fast adapting -lose these neurons every 30 days; regenerate from stem cells in olfactory epithelium -each neuron expresses single OR |
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basic structure of taste system |
-begins in taste buds (50-100 receptor cells, lifespan of <2 weeks) -several types of receptor cells in each bud working together to communicate to the nerve -about 20 axons leave each taste bud (not all receptor cells communicate directly with nerves; use CN VII and IX and X (epiglottis) -nerves synapse on nucleus of solitary tract then thalamus; cortical process unclear -tastant activates ion channel (salt or acid) or GPCR (sweet, umami, or bitter) -any one taste cell has output to several nerves --> blending!! weird |
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transduction of olfactory signals |
-chemicals intercepted by the mucus on olfactory epithelium (OE) and signal is delivered to olfactory bulb (OB) -all axons for one type of OR converge on a single glomerulus -OE inputs from different ORs result in a dispersed ensemble of neurons -in OB we have specific combinations of glomeruli; spatial arrangement is similar among individuals -partially overlapping combinations of OR inputs generate distinct odor perceptions -OB contines into olfactory cortex via the lateral tract to the pyriform cortex |
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different classes of tastants and the signal they create |
-salt: ion channels; amiloride blocks Na+ channel -acid: ion channels; H+ going through amiloride sensitive gNa+ channels; ASICS channels; H+ block of K+ or Ca++; Cl- and Na+ conductances may be gated by H+ -sweet: heterodimerized 7TMD GPCRs (T1R2 and T1R3) -umami: heterodimerized 7TMD GPCRs (T1R1 and T1R3) -bitter: >30 GPCRs respond (TR2s) |
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GPCR taste receptors |
-sweet, umami, and bitter -sometimes use G-protein gustducin -some work through TRPM5 (6 TMD voltage gated K+ channel w/ long N- and C-terminal functional regions) -TRPM5 activated through taste-specific PLC beta 2 |
