Peterson - olfaction & taste Flashcards
innervation for anterior 2/3 of tongue
general sensory - trigeminal nerve
taste - facial nerve
innervation for posterior 1/3 of tongue
general sensory - glossopharyngeal nerve
taste - glossopharyngeal nerve
epiglottis and soft palate
do not detect taste
- detect good vs. bad food and for swallowing
- epiglottis (vagus for taste and sensory)
- soft palate (facial for taste, trigeminal for sensory)
filiform papillae
most abundant, move food, not for taste
fungiform papillae
anterior 2/3 of tongue –> facial nerve
-most abundant
foliate papillae
- posterior –> glossopharyngeal nerve
- anterior –> facial nerve
- sides of tongue
circumvallate papillae
glossopharyngeal nerve
- over 1/2 of taste buds
- on posterior of tongue
cells of the taste buds
- taste cells - detect tastant with microvilli
- supporting (glial) cells
- basal cells - replace dying taste cells
taste pore where tastant travels to activate microvilli
taste receptor communication - 2 ways
- tastant interacts with microvilli –> receptor depolarization –> + Na+ and influx –> release ATP from cell to bind to free nerve ending
- same mechanism except use Ca++ channels and influx to trigger ATP release
salty taste communication
Na+ signaling
-Na+ influx –> depolarization –> ATP release
sour taste communication
acid signaling
- weak acids –> diffuse, dissociate, increase acidity, and activate channels releasing ATP
- strong acids –> activate pH sensitive channel (higher pH induces depolarization)
sweet, umami, and bitter communication
different GPCRs –> dissociate –> 2nd messenger system to release intracellular Ca++ –> ATP release
gustatory pathway
neurons activated by taste –> ganglion –> synapse on nucleus solitary tract
- 1st route: reflexive activity - neurons synapse in dorsal motor nerve of vagus
- 2nd route: travel to cerebral cortex - thalamus –> VPN –> gustatory cortex –> orbital cortex and amygdala
label line vs. cross fiber coding
label line = each axon responds to one tastant better than others
cross fiber = all axons together determine taste
olfactory neurons
bipolar neurons - dendrites detect odorants with cilia
-group of olfactory neurons –> olfactory fila that pass through cribriform plate to olfactory bulb
olfactory receptors
each GPCR has specific protein receptors for odorants
- odorant binds to GPCR –> dissociate G protein –> + adenylyl cyclase and cAMP –> Na+, Ca++ influx, K+ efflux –> Cl- efflux –> AP firing
- Cl- efflux DEPOLARIZES the cell
role of mitral cells
interact with olfactory epith. receptors to convey info. to olfactory tract
- dendrites enter flat end, axons leave pointed end
- different odorants activate different glomeruli
signal pathways of olfactory tract
- trigger anterior olfactory nucleus (AON) - crossing over
2. synapse at olfactory tubercle - attaches to brain
conductive olfactory deficit
prevent odorants from reaching neurons
- nasal polyp
- septal deviation
- inflammation
sensorineural olfactory deficit
injury to CNS or neurons
- head injury
- parkinson’s, Alzheimers
excess activity
tumor causing perceptions of taste or smell
