Chemical Senses Lec09 Flashcards
____ has no major, direct cortical
projections or thalamic input
Olfaction
Olfactory Epithelium has 3 cells:
basal (stem) cells, neurons, & supporting cells
___ cells in the olfactory epithelium renew every 30 days
basal
neurons in the olfactory epithelium are ___polar
bipolar
what do neurons of the olfactory epithelium need to survive?
contact with & tropic support from olfactory bulb to survive
describe signal transduction of smell
–> odorant binds to G-protein receptor (R)
–> G protein (G) & adenyl cyclase (AC) increase
–> cAMP levels increase
–> cyclic nucleotide gated (CNG) ion channel opens
–> cell depolarizes
key ion in smell pathway?>
calcium
Humans have about ___ odorant receptors
1000
1 neuron = ___ odorant receptor type
1
1 odorant receptor type recpgnizesone ___
compoenent of an odorant molecule
odorant encoding is based on a
pattern of responses
*not single neurons
what are the 4 layers of the olfactory bulb?
glomerular, external plexiform, mitral cell, granule cell
what layers in the olfactroy bulb go right to the olfactory cortex
mitral and tufted cells
___ and ___ cells are inhibitory interneurons that modulate mitral & tufted cells
periglomerular and granule
what is the outermost layer?
periglomerular
olfactory neurons projections to CNS is either
1) quadrant-to- quadrant
(2) same-OR-neurons-to-same-glomerulus
weak stimulations are removed via ____ cells, so only the most sensitive / maximally stimulated neuron responds to an odorant.
granule cells
Each glomerulus recognizes different ___
odorants
each odorant receptor recognizes a specific
“odotope”
Odors are identified by overall activation pattern of
glomeruli across the whole bulb
taste invovles innervation by what cranial nerves
7, 9, 10
Gustatory axons innervate the nucleus of the
___ in brainstem
solitary tract (NTS)
the solitary n. of the braisntem projects to the
VPM in the thalamus
what cranial nerve converys oral irratation (the common chemical sense)
trigem
Four primary taste fields = areas of \
greatest sensitivity
Taste buds are all on ___.
papillae