Test 2: Smell and Taste Paths Flashcards
What CNs contribute to taste and smell
CN1 olfactory: smell
CNVII facial, IX glossophary, and X vagal: taste/gustation
How many neurons make up olfaction path
2 neuron circtui with 5 destinations
What are 1neuron characteristics of olfaction
bipolar unmyelinated chemosensitive
- embedded in mucosa of nasal epithelium
- intertwine as fascicle to form olfactory nerve
- project through ethmoid bone to olfactory bulb
What are 2neuron characteristics of olfaction
in olfactory bulb
mitral and trufted cells within glomeruli
-go to 5 different targets
Why is smell vulnerable to injury?
fascicles going through cribiform plate vulnerable to shear forces from head injury
-result in anosmia
What makes up the olfactory nerve
single dendrite with unmyelinatef axon
- cilia hairs
- primary olfactory neyurons
- CB in olfactory epithelium
What is in the glomeruli
dendrites and matrial/tufted cells (2neurons)
-each neuron cilia 1 picks up one oderant and translates into bulb
What are the 5 targets of 2neurons of olfaction
anterior olfactor nucleus olfactory tubercle amygdala piriform cortex entorhinal
What occurs at the anterior olfactory nucleus
sharpen sensory detection
- contralateral anterior olfactory nucleus and bulb input
- coordinates between bulbs
What occurs at the olfactory tubercle
visceral and metabolic responses to smell
-hypothalamus, lateral stria-perforated substence-frontal-hypo
What occurs at the amygdala
emotional response to smell
-limbic system- lateral to uncus in temporal lobe
What occurs in the piriform cortex
concious perception- PRIMARY olfactory cortex
-orbital frontal gyri; anterior to parahippacampus- uncus
What occurs in the entorhinal
memories and forming new ones
-hippocampus- primary gateway
Where does the olfactory tract relay to?
Allocortex (
What is the area where the2neurons deccusate called
anterior commisure
-medial striate through here
Where do higher order smells get translated
primary olfactory output -> orbitofrontal cortex for high order analysis
-orbitofrontal crosses with taste modalitis to get smell
How is taste transduced?
By gustatory receptors clustered in tastebuds
- trasnduce sweet, sour, salty, bitter, and umami
- excite pseudounipolar sensory 1neurons for that specific taste
What portions of the mouth do the 3 CN involved in taste transduce?
Facial (VII)- aka corda tempony- intermediate facial
- anterior 2/3 tongue
- 1CB genicular ganglion
Glossopharyngeal (IX)
- posterior 1/3 tongue and pharynx
- 1CB inferior pharyngeal ganglia
Vagus (X)
- larynx, epilottis
- 1CB inferior vagal ganglia
What are taste receptor cells
saliva will come and bring taste cells throughout mouth down into trenches where taste buds are
What are the 3 type of taste buds and where are they
Circumvallae papilae: IX BITTER -big posterior -50% all tastebuds Foliate papilae: IX SOUR -deep latearl -25% all tastebuds Fungiform papilae: VII SWEET/UMAMI/SALTY -front -25% all tastebuds
What is 1CB of taste
genicu gang for facial
inferior gang for glosso and vagal
Where does 1neuron go and where does synapse on 2CB for taste
Travel in solitary tract to solitary nucleus in medulla
Where are 2CB for taste
ROSTRAL Solitary nuclues -rostral medulla
Where do 2CB go for taste
travel ipsilaterally in central tegmentum path to VPM
Where are 3CB of taste
VPM
travel to primary gustatory cortex (insula) or orbital frontal operculum
-via internal capsule and coronar radiate
What is the difference in proccessing of primary gustatory cortex vs, orbital frontal gyrus
Primary: discriminative taste
Operc: enhance descrimination with smell
Where is the solitary tract/nucleus for taste
ROSTRAL medulla
- caudal is visceral sensory
- nucleus is on outside of tract
