Olfaction and taste Flashcards
Pathway
Long receptors in olfactory epithelium send axons through the cribriform plate to synapse in olfactory bulb
Basal cells
Stem cells to allow turnover of olfactory receptor cells
Golf coupling
Activates adenylyl cyclase so increases cAMP, opening CNG channels to allow Na+/Ca2+ in to depolarise the soma
Ca2+ opens Cl- channels and since these neutrons accumulate Cl-, this opening will cause Cl- exit which increases depolarisation
Olfactory adaptation
Ca-CaM acts to decrease channel affinity for cAMP to decrease depolarisation
Mitral cells
synapses with receptor cells in glomerulus
+ makes reciprocal dendron-dendritic connections with periglomerular and granule cells
-> Acts to stimulate these cells, causing inhibition on other mitral cell via lateral inhibition
Granule cells
Inhibit neighbouring cells around stimulated mitral cell to sharpen odour tuning
Direct inotropic receptors
Acid, salt
Indirect metabotropic receptors
Bitter, sweet, umami
Involves betagmma activating PLC to hydrolyse PIP2 so IP3 can liberate Ca2+ and open TrpM5 for Na+ to enter and Panx1 for ATP to leave
Umami heterodimeric receptor
T1R1 + T1R3
Sweet heterodimeric receptor
T1R1 + T1R3
ATP as a puringeric transmitter
Released from Panx1 hemichannel due to Ca2+ action (via IP3); can carry signal to presynaptic cells
Acid transduction
H-Acid diffuses into cell and dissociates
H+ inhibits K+ channel to cause depolarisation and opening of Ca2+ channels
Across fibre code
Afferent fibres receive broadly tuned input from presynaptic cells and ATP from receptor cells
Compare pattern of afferent activity in fibres to decode the combined signal
Trace amine associated receptors
G protein coupled to allow signalling and detection of volatile amine odourants
May be involved in mood shift and fertility
Cortical representation of taste
Insula, and operculum
