Chemosensation

Question 1

Define
ageusia

anosmia

Answer 1

ageusia = loss of taste

anosmia = loss of smell

Question 2

simple test for smell

simple test for taste

Answer 2

1) scratch and sniff test )

2) sip, spit, and rinse test or chem apply to different areas of tongue

Question 3

when someone comes in saying they lost taste

Answer 3

likely lost sense of flavor which is due to sense of smell

Question 4

smell receptor cell structure?
structure?

innerv by?

primary sensory nucleus?

Answer 4

ciliated bipolar neuron

innerv by CN 1

olfactory bulb as

Question 5

taste receptor cell

structure
CN?

each cell tuned to what?
how is tongue mapped?

primary CNS nucleus

Answer 5

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

Question 6

Chemisthesis
receptor cell

CN?
detection of

primary sensory nucleus

Answer 6

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

Question 7

Front 2/3 of tongue
Which CN for touch, hot, cold

Which CN for taste

Answer 7

CN V

CN 7= taste

Question 8

Back 1/3 tongue

which for tast eand touch

Answer 8

CN 9

Question 9

difference in route of access of odorants
ortho-nasal

retro-nasal

Answer 9

ortho-nasal = through nostril

retro-nasal = enter mouth traveling through concha to olfactory epith

Question 10

how is odor info transmitted from receptor epith to olfactory bulb

Answer 10

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

Question 11

olfactory receptor neuron expressing same olfactory receptor protein project axon to __

Answer 11

same glomerulus

convergance of axons with same chem specificity = ability of olfactory to recog structurally different odorants

Question 12

primary principle of encoding odor quality =

compare to olfactory epith

Answer 12

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

Question 13

olfactory receptor neurons can detect how many molec?

Answer 13

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

Question 14

output of olfactory bulb

Answer 14

projects directly to cortex

1) axons of output cells from bulb collect into lateral olfactory tract
2) project on to olfactory cortex + amygdala

Question 15

olfactory cortex made of?

divided into what areas

Answer 15

lateral olfactory gyrus + part of uncus

divided into areas including piriform cortex, acecessory olfactory nucleus and olfactory tubercle

Question 16

piriform cortex projects

function of that structure

Answer 16

to orbitofrontal cortex

orbitofrontal cortex = assoc area for olfactory and taste = conscious apprec of smell

Question 17

other connections with limbic system

amygdala + olfactory tubercle are interconnect with

Answer 17

hypothalamus

subconscious regul of hmeostasis, biological rhythms

Question 18

entorhinal cortex feeds into ?

function

Answer 18

feeds into hypothal

storage and retrieval of memories

Question 19

3 types of gustatory papillae and which cranial nerve provide their innerv

Answer 19

1) fungiform = anterior tongue, CN 7
2) foliate = CN 7
3) circumvallate = posterior tongue, CN 9

Question 20

all taste buds in pharynx, extreme posterior tongue, esoph and epiglottis supplied by?

Answer 20

supplied by vagus nerve

Question 21

5 primary taste qualitys and whether transduction involves ion channels or GPCR

Answer 21

1) salty or sour = ion channesl = ionic stim

2) sweet, bitter, umami (glutamate) = metabotropci receptor, GPCR = more complex

Question 22

trace pathway conveying taste from taste bud to gustatory cortex

Answer 22

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

Question 23

conscious appreciation of taste where?

Answer 23

insular cortex

Question 24

secondary gustatory cortex
located where?
receive projections from

Answer 24

located in orbitofrontal cortex

receives projection from primary gustatory area in interior insula/olfactory insula areas

Question 25

orbitofrontal cortex important for

Answer 25

integration of taste and smell for flavor

Question 26

sbuconscious taste pathways

nucleus of solitary tract relays to where?
for food intake regul/visceral reaction
for gag
for swallow
for salivation

Answer 26

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