Ch. 7 Taste, Smell, Mechano (Book)

Question 1

chemoreceptors are specialized for info about the… and 2 types

Answer 1

chemical envir and transmitting it to neurons

gustatory (taste) receptors

olfactory receptors

Question 2

airborne molecules first pass through a layer of _______ _______ before they reach olfactory receptors

Answer 2

aqueous solution

Question 3

sensilla/sensillum

Answer 3

hollow hairlike projections with a pore that allows stimulant molecules to reach sensory cells

Question 4

taste in a housefly

Answer 4

on its proboscis or feet each sensillum has dendrites from many receptor cells

each is sensitive to a different chemical stimulus

Question 5

will chemical stimulation of just a single sensillum of a fly provoke a behavioral response?

Answer 5

yes, it will lower its proboscis to feed

Question 6

where are taste receptors found in terrestrial vertebrates?

Answer 6

tongue

epiglottis

back of the mouth

pharynx/upper esophagus

Question 7

taste receptors in vertebrates are grouped into _____ ___ surrounded by ____ ____

Answer 7

taste buds, basal cells

Question 8

basal cells

Answer 8

surround taste buds and are progenitor cells that give rise to new taste receptors (they die in ~10 days)

Question 9

5 taste qualities

Answer 9

sweet

salt

sout

bitter

umami (MSG)

Question 10

evolution of taste qualities

Answer 10

sweet - rich in calories

salt - maintain water balance

sour/bitter - toxic/danger

Question 11

salty mechanism

Answer 11

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

Question 12

sour mechanism

Answer 12

H+ ions enter amiloride-sensitive Na channels of apical memb

Block K+ channels

depolarizes cell

Question 13

sweet mechanism

Answer 13

alanine binds receptors that use a G protein to start a cascade that ends in the closing of K channels

Question 14

bitter mechanism

Answer 14

quinine blocks K channels in apical memb

small resting Na current depolarizes the cell

Question 15

bitter mechanism under study

Answer 15

quinine binding activates G protein gustducin

actives phospholipase C which increases IP3 to release Ca

Question 16

do vertebrate taste receptors make APs?

Answer 16

yes, but don’t have axons

synapse onto neurons whose axons run into the facial, glossopharyngeal, and vagus nerves

Question 17

labeled line coding

Answer 17

receptors connected to a specific set of axons

Question 18

olfactory receptors in vertebrates

Answer 18

found in the nasal cavity (line turbinates)

arranged so a stream of air or water flows over them during ventilation

Question 19

vomeronasal organ

Answer 19

olfactory chamber that mediates chemical communication btw animals of the same species

for pheremones

Question 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

Answer 20

dendrite, knob, surface

thin cilia covered in the protein soln mucus

Question 21

only _______ olfactory neruons respond to odors

Answer 21

ciliated

Question 22

nasal olfactory transduction cascade

Answer 22

G protein activates adenylyl cyclase that increases intracellular cAMP

cAMP opens cation-selective channels –> depolarization

Question 23

APs from olfactory receptor axons carry the signal where

Answer 23

olfactory bulb of the brain

Question 24

glomeruli

Answer 24

spherical clusters of neurons

ex. olfactory bulbs of insects and invertebrates/vertebrates

Question 25

what kind of stimulus activates mechanoreceptors

Answer 25

a stretch or distortion of plasma membrane uses ion channels

Question 26

sensory bristle

Answer 26

found of the surface of insects a stiff hair associated with a single bipolar sensory neuron

Question 27

endolymph

Answer 27

fluid with a high [K+] that bathes dendrites of sensory bristles

Question 28

what happens when an insect sensory bristle is moved

Answer 28

the dendrite is deformed and stretch-actived cation-selective channels are opened K+ flows in (unusual) instead of out, which depolarizes cell

Question 29

hair cells of vertebrates

Answer 29

extremely sensitive mechanoreceptors many cilia from the apical end of each cell coupled by kinocilium to accessory structures

Question 30

2 classes of hair cell cilia

Answer 30

kinocilium (single) stereocilia 20-300 (non-motile)

Question 31

kinocilium microtubule arrangement

Answer 31

9+2 like other motile cilia

Question 32

stereocilia arrangement

Answer 32

increasing length from one side of the cell to another mechanically linked and move as a bundle

Question 33

ultimately, movement of the ________ produces an electrical signal (hair cells)

Answer 33

stereocilia

Question 34

when the stereocilia bends toward the kinocilium, the hair cell ______ and when the stereocilia bends away from the kinocilium the hair cell ________

Answer 34

depolarizes, hyperpolarizes

Question 35

lateral line system

Answer 35

fishes and amphibians external receptors based on hair cells detects movement in water

Question 36

lateral line system receptors

Answer 36

kinocilia of many hair cells embedded in an accessory structure called a cupula cupula bends toward kinocilia when displaced

Question 37

at rest, about __% of channels in a hair cell are open, producing a resting potential of about -____

Answer 37

15%, -60mV

Question 38

do hair cells produce APs?

Answer 38

no, they release nt in a graded fashion onto primary afferent neurons

Question 39

asymmetry of hair cell output

Answer 39

displacement toward kinocilium produces larger depolarization than same displacement away from kinocilium (small hyperpolarization)

Question 40

stratocyst

Answer 40

organ that detects an animal's position and acceleration with respect to gravity

Question 41

stratocyst structure

Answer 41

hollow fluid-filled cavity lined with mechanoreceptors that contact the stratolith

Question 42

stratolith

Answer 42

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

Question 43

what happens to the startolith when an animal moves

Answer 43

it rests on different regions of the stratocyst epithelium, which stimulates tonic discharge from ciliated receptor cells

Question 44

2 functions of the vertebrate ear

Answer 44

report position of the animal hearing

Question 45

in vertebrates, the organs of equilibrium reside in a membranous labyrinth with 2 chambers...

Answer 45

sacculus and utriculus surrounded by bone and filled with endolymph

Question 46

utriculus

Answer 46

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

Question 47

all the hair cells in a semicircular canal have their kinocilia on the ____ side

Answer 47

same so all are excited or inhibited at once

Question 48

maculae

Answer 48

3 patches of hair cells below the semicircular canals Detect tilt

Question 49

what is sound

Answer 49

a mechanical vibration that propagates through air or water travels as waves

Question 50

the external ear functions as a ______

Answer 50

funnel that collects sound waves from the air and concentrates the pressure on the eardrum (tympanic membrane)

Question 51

external structures of the ear... pinna and tragus

Answer 51

help collection of sound waves and modify directional sensitivity

Question 52

to detect sound, airborne vibrations must be transmitted where

Answer 52

from the outer and middle ear to the fluid-filled inner ear where the auditory receptor hair cells are

Question 53

auditory ossicles

Answer 53

malleus incus stapes energy from moving eardrum is transmitted to the ossicles through the oval window to the inner ear

Question 54

cochlea

Answer 54

fluid-filled chamber that looks like a snail shell containing the receptor hair cells hair cells encode frequency and intensity of sound

Question 55

perilymph

Answer 55

in the cochlea high [Na+]

Question 56

organ of corti

Answer 56

has cochlear hair cells and bathed in endolymph

Question 57

inner hair cells of organ of corti vs outer hair cells

Answer 57

inner hair cells: detect vibrations outer hair cells: touch tectorial memb and change length rapidly to amplify vibrations

Question 58

cochlear electrical signals reflect _______ of receptor currents from numerous hair cells

Answer 58

summation transduction happens with movement of basilar memb bends tips of stereocilia laterally

Question 59

_______ K+ current depolarizes hair cells of ear

Answer 59

inward (unusual b/c of high K+ in endolymph)

Question 60

tip links

Answer 60

fine strands that connect each stereocilium to its taller neighbor when bent, all move and many ion channels are opened TRPA1 channels

Question 61

electrical resonance frequency

Answer 61

the frequency a hair cell responds maximally to

Question 62

Basilar membrane stuff

Answer 62

Diff freq activate diff regions Stiff narrow end = high freq and amplitude Wide floppy end = low freq and amplitude