Chemosensation Flashcards
Define
ageusia
anosmia
ageusia = loss of taste
anosmia = loss of smell
simple test for smell
simple test for taste
1) scratch and sniff test )
2) sip, spit, and rinse test or chem apply to different areas of tongue
when someone comes in saying they lost taste
likely lost sense of flavor which is due to sense of smell
smell receptor cell structure?
structure?
innerv by?
primary sensory nucleus?
ciliated bipolar neuron
innerv by CN 1
olfactory bulb as
taste receptor cell
structure
CN?
each cell tuned to what?
how is tongue mapped?
primary CNS nucleus
modified epith cell
synapse on to nerve fiber from cranial ganglion cell to CN 7, 9, 10
tuned to only one taste quality but diff sensitivity all over tongue
primary CNS nucleus = nucleus of solitary tract
Chemisthesis
receptor cell
CN?
detection of
primary sensory nucleus
free nerve ending of cranial ganglion cell
innerv by CN 5
detection of irrigant chemicals by trigeminal nerve endings
primary sensory nucleus = spinal trigeminal nucleus
Front 2/3 of tongue
Which CN for touch, hot, cold
Which CN for taste
CN V
CN 7= taste
Back 1/3 tongue
which for tast eand touch
CN 9
difference in route of access of odorants
ortho-nasal
retro-nasal
ortho-nasal = through nostril
retro-nasal = enter mouth traveling through concha to olfactory epith
how is odor info transmitted from receptor epith to olfactory bulb
1) axons of olfactory neuron run btwn bulb and epith
2) cross ethmoid bone and converge on glomeruli
1000 olfactory on 2-25 mitral cell
olfactory receptor neuron expressing same olfactory receptor protein project axon to __
same glomerulus
convergance of axons with same chem specificity = ability of olfactory to recog structurally different odorants
primary principle of encoding odor quality =
compare to olfactory epith
odor specific map of glomeruli in olfactory bulb = chemical map
olfactory receptor neurons expressing same receptor protein project to same glomerulus and convergance from neurons with same specificity
diff from olfactory epith = receptor cells expressing common receptor scattered throughout
olfactory receptor neurons can detect how many molec?
only one
recog molec config of antigen, epitope (like anything with 6 carbon)
when binds olfactory neuron, will trigger both hexane and hexane + ring but perception diff because one neighboring neuron may recog just ring so you get combo activ of 6 carbon and a neuron sensitive to ring
output of olfactory bulb
projects directly to cortex
1) axons of output cells from bulb collect into lateral olfactory tract
2) project on to olfactory cortex + amygdala
olfactory cortex made of?
divided into what areas
lateral olfactory gyrus + part of uncus
divided into areas including piriform cortex, acecessory olfactory nucleus and olfactory tubercle
piriform cortex projects
function of that structure
to orbitofrontal cortex
orbitofrontal cortex = assoc area for olfactory and taste = conscious apprec of smell
other connections with limbic system
amygdala + olfactory tubercle are interconnect with
hypothalamus
subconscious regul of hmeostasis, biological rhythms
entorhinal cortex feeds into ?
function
feeds into hypothal
storage and retrieval of memories
3 types of gustatory papillae and which cranial nerve provide their innerv
1) fungiform = anterior tongue, CN 7
2) foliate = CN 7
3) circumvallate = posterior tongue, CN 9
all taste buds in pharynx, extreme posterior tongue, esoph and epiglottis supplied by?
supplied by vagus nerve
5 primary taste qualitys and whether transduction involves ion channels or GPCR
1) salty or sour = ion channesl = ionic stim
2) sweet, bitter, umami (glutamate) = metabotropci receptor, GPCR = more complex
trace pathway conveying taste from taste bud to gustatory cortex
1) primary afferent from tongue via CN 7, 9, 10
2) synapse on 2nd order neuron in ipsil Nucleus of solitary tract
3) send axon bilaterally to medial ventrobasal thalamus via taste lemniscus
4) then project to insular cortex (conscious appreciation of taste)
5) project to primary gustatory area in interior insula and then to secondary gustatory cortex
conscious appreciation of taste where?
insular cortex
secondary gustatory cortex
located where?
receive projections from
located in orbitofrontal cortex
receives projection from primary gustatory area in interior insula/olfactory insula areas
orbitofrontal cortex important for
integration of taste and smell for flavor
sbuconscious taste pathways
nucleus of solitary tract relays to where? for food intake regul/visceral reaction for gag for swallow for salivation
1) NST to hypothal and amygdaala for food intake regul and visceral reaction
2) NST also nucleus ambiguous (gag)
NST to nucleus ambig/hypoglossal for swallow
NST to superior and inf salivatory nucleus for salivation
