Flashcards in Ch. 7 Taste, Smell, Mechano (Book) Deck (62)
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1
chemoreceptors are specialized for info about the... and 2 types
chemical envir and transmitting it to neurons
gustatory (taste) receptors
olfactory receptors
2
airborne molecules first pass through a layer of _______ _______ before they reach olfactory receptors
aqueous solution
3
sensilla/sensillum
hollow hairlike projections with a pore that allows stimulant molecules to reach sensory cells
4
taste in a housefly
on its proboscis or feet each sensillum has dendrites from many receptor cells
each is sensitive to a different chemical stimulus
5
will chemical stimulation of just a single sensillum of a fly provoke a behavioral response?
yes, it will lower its proboscis to feed
6
where are taste receptors found in terrestrial vertebrates?
tongue
epiglottis
back of the mouth
pharynx/upper esophagus
7
taste receptors in vertebrates are grouped into _____ ___ surrounded by ____ ____
taste buds, basal cells
8
basal cells
surround taste buds and are progenitor cells that give rise to new taste receptors (they die in ~10 days)
9
5 taste qualities
sweet
salt
sout
bitter
umami (MSG)
10
evolution of taste qualities
sweet - rich in calories
salt - maintain water balance
sour/bitter - toxic/danger
11
salty mechanism
salty tastants like NaCl dissociates in water
Na enters receptors through a special Na channel that is always open in the apical memb (blocked by amiloride)
depolarizes cell
12
sour mechanism
H+ ions enter amiloride-sensitive Na channels of apical memb
Block K+ channels
depolarizes cell
13
sweet mechanism
alanine binds receptors that use a G protein to start a cascade that ends in the closing of K channels
14
bitter mechanism
quinine blocks K channels in apical memb
small resting Na current depolarizes the cell
15
bitter mechanism under study
quinine binding activates G protein gustducin
actives phospholipase C which increases IP3 to release Ca
16
do vertebrate taste receptors make APs?
yes, but don't have axons
synapse onto neurons whose axons run into the facial, glossopharyngeal, and vagus nerves
17
labeled line coding
receptors connected to a specific set of axons
18
olfactory receptors in vertebrates
found in the nasal cavity (line turbinates)
arranged so a stream of air or water flows over them during ventilation
19
vomeronasal organ
olfactory chamber that mediates chemical communication btw animals of the same species
for pheremones
20
each receptor in the main olfactory epithelium has a long, thin _______ that terminates in a small ____ at the _____. what is found on the knobs
dendrite, knob, surface
thin cilia covered in the protein soln mucus
21
only _______ olfactory neruons respond to odors
ciliated
22
nasal olfactory transduction cascade
G protein activates adenylyl cyclase that increases intracellular cAMP
cAMP opens cation-selective channels --> depolarization
23
APs from olfactory receptor axons carry the signal where
olfactory bulb of the brain
24
glomeruli
spherical clusters of neurons
ex. olfactory bulbs of insects and invertebrates/vertebrates
25
what kind of stimulus activates mechanoreceptors
a stretch or distortion of plasma membrane
uses ion channels
26
sensory bristle
found of the surface of insects
a stiff hair associated with a single bipolar sensory neuron
27
endolymph
fluid with a high [K+] that bathes dendrites of sensory bristles
28
what happens when an insect sensory bristle is moved
the dendrite is deformed and stretch-actived cation-selective channels are opened
K+ flows in (unusual) instead of out, which depolarizes cell
29
hair cells of vertebrates
extremely sensitive mechanoreceptors
many cilia from the apical end of each cell
coupled by kinocilium to accessory structures
30
