Flashcards in Ch. 7 Taste, Smell, Mechano (Book) Deck (62):
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
2 classes of hair cell cilia
kinocilium (single)
stereocilia 20-300 (non-motile)
31
kinocilium microtubule arrangement
9+2 like other motile cilia
32
stereocilia arrangement
increasing length from one side of the cell to another
mechanically linked and move as a bundle
33
ultimately, movement of the ________ produces an electrical signal (hair cells)
stereocilia
34
when the stereocilia bends toward the kinocilium, the hair cell ______ and when the stereocilia bends away from the kinocilium the hair cell ________
depolarizes, hyperpolarizes
35
lateral line system
fishes and amphibians
external receptors based on hair cells
detects movement in water
36
lateral line system receptors
kinocilia of many hair cells embedded in an accessory structure called a cupula
cupula bends toward kinocilia when displaced
37
at rest, about __% of channels in a hair cell are open, producing a resting potential of about -____
15%, -60mV
38
do hair cells produce APs?
no, they release nt in a graded fashion onto primary afferent neurons
39
asymmetry of hair cell output
displacement toward kinocilium produces larger depolarization than same displacement away from kinocilium (small hyperpolarization)
40
stratocyst
organ that detects an animal's position and acceleration with respect to gravity
41
stratocyst structure
hollow fluid-filled cavity lined with mechanoreceptors that contact the stratolith
42
stratolith
structure made of sand grains, calcarous concentrations, or another dense material
must have a higher specific gravity than surrounding fluid
acquired from the animal's surroundings or secreted by stratocyst epithelial cells
43
what happens to the startolith when an animal moves
it rests on different regions of the stratocyst epithelium, which stimulates tonic discharge from ciliated receptor cells
44
2 functions of the vertebrate ear
report position of the animal
hearing
45
in vertebrates, the organs of equilibrium reside in a membranous labyrinth with 2 chambers...
sacculus and utriculus surrounded by bone and filled with endolymph
46
utriculus
gives rise to 3 semicircular canals of the inner ear
hair cells here detect acceleration of the head, endolymph moves the cupula --> bends cilia of hair cells
47
all the hair cells in a semicircular canal have their kinocilia on the ____ side
same
so all are excited or inhibited at once
48
maculae
3 patches of hair cells below the semicircular canals
Detect tilt
49
what is sound
a mechanical vibration that propagates through air or water
travels as waves
50
the external ear functions as a ______
funnel that collects sound waves from the air and concentrates the pressure on the eardrum (tympanic membrane)
51
external structures of the ear... pinna and tragus
help collection of sound waves and modify directional sensitivity
52
to detect sound, airborne vibrations must be transmitted where
from the outer and middle ear to the fluid-filled inner ear where the auditory receptor hair cells are
53
auditory ossicles
malleus incus stapes
energy from moving eardrum is transmitted to the ossicles through the oval window to the inner ear
54
cochlea
fluid-filled chamber that looks like a snail shell containing the receptor hair cells
hair cells encode frequency and intensity of sound
55
perilymph
in the cochlea
high [Na+]
56
organ of corti
has cochlear hair cells and bathed in endolymph
57
inner hair cells of organ of corti vs outer hair cells
inner hair cells: detect vibrations
outer hair cells: touch tectorial memb and change length rapidly to amplify vibrations
58
cochlear electrical signals reflect _______ of receptor currents from numerous hair cells
summation
transduction happens with movement of basilar memb bends tips of stereocilia laterally
59
_______ K+ current depolarizes hair cells of ear
inward (unusual b/c of high K+ in endolymph)
60
tip links
fine strands that connect each stereocilium to its taller neighbor
when bent, all move and many ion channels are opened TRPA1 channels
61
electrical resonance frequency
the frequency a hair cell responds maximally to
62