Physiology of Taste & Smell Flashcards
Taste receptor cells are comprised _________ of that synapse on _____
modified epithelial cells ; neurons
olfactory receptor cells are
neurons
The receptors for taste are primarily located in the taste buds, which contains both _______ and ___________ cells
sensory (receptor) ; supportive
The receptor cells found in the taste buds contain microvilli on their ______ ends
apical
taste buds have a lifespan of about
10 days
microvilli project into an opening called the
taste pore
Gustants that are dissolved in saliva can bind to these receptors and initiate
downstream effects
The binding of the gustant stimulates a ________ which ______ voltage-gated calcium channels
depolarization ; opens
The binding of the gustant stimulates a depolarization whichs open voltage-gated calcium channels - this stimulates the release of a ________, triggering _________ in afferent neurons to the brain
transmitter ; action potentials
cravings for non-food items like detergents, clay, soil (called Pica) is associated with
iron-deficiency anemia
the salt receptor is a
sodium channel
The microvilli of sensory taste cells contain a receptor for sodium that also acts as a
channel
The sodium receptor that acts as a sodium channel is called the ________
epithelial sodium channel (ENaC)
The movement of sodium down its electrochemical gradient into the taste receptor cell causes a
depolarization
The movement of sodium down its electrochemical gradient into the taste receptor cell causes a depolarization which leads to ___________ and the __________
downstream effects and the release of a transmitter
sour foods contain high levels of
hydrogen ions (H+)
There are multiple ways in which hydrogen ions can be detected by the taste cells:
Hydrogen ions can enter the cell through the _______ utilized for salt recognition
ENaC channel
There are multiple ways in which hydrogen ions can be detected by the taste cells:
Hydrogen ions can also bind to and activate channels that facilitate _____ INFLUX
Na+
There are multiple ways in which hydrogen ions can be detected by the taste cells:
Hydrogen ions can bind to channels and block ____ EFFLUX
K+
The multiple ways H+ ions can be detected by the taste cells are most likely initiated SIMULTANEOUSLY, with the end effect of cell ________ and
__________
depolarization ; transmitter release
Umami receptors are activated by _________, such as glutamine, which are important components of muscles, organs, transport proteins, etc
amino acids
The umami receptors are stimulated by
monosodium glutamate (MSG)
Despite the great variance in these 3 taste sensations, the signaling mechanisms are the same for ______, _____ , and ______ modalities
bitter
sweet
umami
For bitter/sweet/umami:
The gustant binds to a _________ and _______ the G-protein
G-protein coupled receptor ; activates
For bitter/sweet/umami:
The alpha subunit of the G-protein activates the enzyme _______
phospholipase C
For bitter/sweet/umami:
The alpha subunit of the G-protein activates the enzyme phospholipase C, which cleaves PIP2 into ____ and _____
DAG and IP3
For bitter/sweet/umami:
IP3 _______ intracellular calcium levels, leading to the ______ of a non-specific cation channel
increases ; opening
For bitter/sweet/umami:
The influx of cations such as sodium _______ the taste receptor cell, leading to
depolarizes ; transmitter release
which is the better developed sense in humans: olfaction or taste?
olfaction
olfactory receptor cells have a lifespan of
4-8 weeks
Olfactory cells have small ______ at one end that detect _________
dendrites ; chemical stimuli
After dendrites on olfactory cells detect chemical stimuli, AXONS carry this information ________
centrally
The receptors for olfaction can be found in the ______ portion of the nasal cavity
superior
Despite the wide diversity of smells that can be detected, there is only believed to be a _______ messenger mechanism utilized by the olfactory system
1 second
________ in the olfactory epithelium are responsible for the formation of new receptor cells
Basal cells
Which cells function similar to glial cells, providing nutrients and assisting the function of the olfactory receptor cells
supportive cells
The ________ also produce mucus, which is necessary for the collection and detection of odorant molecules
support cells
Dendrites of the olfactory receptor cells project into this ______ layer
mucus
Odorants bind to receptors on
the dendrites and initiate changes in ______ that lead to _______
ion flux ; depolarization
If the depolarization initiated by an odorant binding is of a
significant enough magnitude, an ________ is generated in the axon of the __________ cell
action potential ; olfactory receptor
The electrical signal generated in the axon of the olfactory receptor cell is propagated via the ________ nerve to the _________
olfactory ; olfactory bulb
It appears that all olfactory neurons utilize the same ________ pathway to initiate depolarization
second-messenger
The binding of an odorant to a G-protein coupled receptor activates a G-protein called
Golf
The _____ subunit of Golf exchanges a bound _____ for _____
alpha ; GDP ; GTP
The activated _____ subunit dissociates from the _______ complex, and the alpha subunit
activates _______
alpha ; beta-gamma ; adenylyl cyclase
Adenyl cyclase converts _____ into _____
ATP ; cAMP
cAMP binds to, and opens a
non-specific cation channel
Sodium and calcium flow _____ their electrochemical gradients into the ________
down ; olfactory receptor cell
The INFLUX of calcium activates a
chloride channel
Olfactory cells are unique in that they contain a HIGH concentration of
chloride
Chloride flows ____ of the cell, producing a _______
out ; depolarization
If the graded potential produced during the second-messenger pathway is of significant enough magnitude, an _______ is generated in the ________ of the axon
action potential ; initial segment
The frequency of these action potential is proportional to the
concentration of the odorant
