lecture 8: CN VII-CN XII Flashcards
Sensory receptors that detect internal chemical stimuli?
internal organ chemoreceptors
internal organ chemoreceptors: ________ to conscious awareness
Tracking concentrations of _________,_______,_______
Inaccessible
oxygen, glucose, and neuroactive hormones
Both __________ and ________ senses are responsible for detecting external chemical stimuli
gustatory (taste) and olfactory (smell)
Gustatory (taste) is a part of the ________ cavity
Olfactory (smell) is a part of the ______ cavity
oral
nasal
What allows you to sense: heat of chili, coolness of methol (mouth) sting of ammonia (nose/eye)
chemosensitive endings; CN V-trigeminal, through somatosensory
papillae on the tongue:
-“surrounded by a wall”
-“leaf-like”, lateral tongue
-“mushroom form”
circumvallate papillae
foliate papillae
fungiform papillae
Circumvallate Papillae
Location:
Number:
Tatse Buds:
Innervation:
Posterior 1/3 of the tongue, near the oropharynx.
8-12 in total
Each papilla has around 250 taste buds
CN IX (Glossopharyngeal nerve) is responsible for both chemical and common somatosensory stimuli
Foliate Papillae
Location:
Number:
Taste Buds:
Innervation: -chemical & somatosensory
middle to posterior lateral tongue
10 on each side - ea. contains 100-150 taste buds
CN VII/CN V for chemical stimuli
CN V/XI for somatosensory sensation
Fungiform Papillae
Location:
Number:
Taste Buds:
Innervation:
Anterior 2/3 of tongue, oral cavity
200-300 in total with ea. contains
3-5 taste buds
CN VII/V- chemical stimuli
CN V for somatosensory stimuli
Why would someone like foods more than others: gourmet
huge variation of total taste buds: >100 folds
Taste receptor cells
cell type:
number:
lifespan:
specialized spindle-shaped epithelial cells
100 in each taste bud
Lasts 1-2 weeks; renewal via basal cell differentiation.
Taste receptor cells
properties:
microvilli:
synapses: occur at the base, connecting with dendrites of CN __________, __________, and __________ (4), not with CN __________.
Taste receptor cells have glial properties, not neurons.
Present, with taste pores
on the tip.
CN VII, IX, and X (4), not CN V.
Taste receptors cell
communication:
Direct communication through gap junctions (5), forming electric synapses.
Gathering of somata of 1st-order neurons:
Ganglia of CN VII, IX, and X
Picture these ganglia as social hubs where 1st order neurons mingle and exchange information:
GG: Geniculate ganglia for
IG IX: Inferior ganglion for
IG X: Interior ganglion for
CN VII
CN IX
CN X
Where are 2nd order neurons conducted?
solitary nuclei
Chemical molecules transduce taste receptor cells (stimulate the sense of tatse) -
Tastants
Salty
-Mechanism: ionotropic channels with _____/_____ ions.
-Results: Direct ________ of the taste cell membrane.
sodium/potassium
depolarization
Sour
-Mechanism: Ionotropic channels with __________ ions.
-Results: Direct ________ of the taste cell membrane.
H+ (hydrogen ion)
depolarization
Sweet/Umami/Bitter
Mechanism: __________ receptors.
G-protein coupled receptors (GPCRs)
The following statement is True or False.
Activation of taste receptors results in action potentials?
False: graded potential
Similar to salty or sour ion channels _______ helps humans detect harmful/toxic foods.
6th taste: ammonium chloride
Which CN is being described?
-senses light ad responsible for vision
-constricts pupil and controls movement of eyeball
CN II (optic)
CN III (oculomotor)
Taste projection pathway is ipsilateral or contralateral projection?
ipsilateral
Taste projection pathway:
1st order neuron
2nd order neuron
3rd order neuron
Then project to ________lobe
geniculate/inferior ganglia
solitary nucleus
VPM of thalamus
insular
Which of the following CN is in the somatosensory pathway for chemical sensation?
CN V
Where is the nuclei of CN VII, facial n located?
lateral pontomedullary junction
Cranial nuclei associated with CN VII.
Ss:
Sm:
Vs:
Vm:
Ss: spinal Trigeminal nucleus
Sm: Facial Motor Nuclei
Vs: Solitary Nucleus
Vm: Superior Salivatory Nucleus