Chemosensation Flashcards
taste receptor morphology
modified epithelial cell located inside a taste pore. Synapses on CN 7, 9, or 10 ganglion fiber
Conscious taste neural pathway
Taste bud –> cranial nerve –> solitary tract nucleus –> VPM thalamus –> insular cortex
role of trigeminal nerve in chemosensation
chemesthesis (detection of noxious stimuli). Free nerve ending of CN 5 ganglion cell –> SpV
smell receptor morphology
ciliated bipolar neurons
How is an odor identified?
via a recognized pattern of activity across olfactory glomeruli
What are the three types of gustatory papillae?
fungiform, foliate, circumvallate
Describe fungiform papillae
anterior portion of tongue. chorda tympani branch of CN 7 (anterior 2/3 of tongue)
Describe foliate papillae
on sides of tongue. CN 9 innervation
Describe circumvallate papillae
Posterior tongue. CN 9 innervation
Where are the taste receptors innervated by CN 10?
oropharynx
5 primary taste qualities
sweet, sour, salty, bitter, umami (savory, MSG)
Which taste qualities are transduced via ion channels?
salty and sour
Which taste qualities are transduced via GPCRs?
sweet, bitter, umami
Describe the orthonasal route of odorant access to olfactory epithelium
in through nostrils –> olfactory epithelium
describe the retronasal route of odorant access to olfactory epithelium
mouth –> oropharynx –> nasopharynx –> olfactory epithelium
Odor transduction pathway
Odorant binds receptor –> G protein activation –> cAMP –> influx of Na (depolarization) and Ca –> opened Ca-gated Cl channels –> Cl efflux –> further depolarization –> activated olfactory glomeruli
Olfactory pathway for memory
olfactory bulb –> entorhinal cortex –> hippocampus –> memories
Olfactory pathway for conscious perception of smell
Olfactory bulb –> piriform cortex –> orbitofrontal cortex –> conscious perception of smell
Olfactory pathway for visceral reactions and homeostasis
Olfactory bulb –> olfactory tubercle and amygdala –> hypothalamus –> visceral reactions and homeostasis
