Ch. 7 Taste, Smell, Mechano (Book) Flashcards Preview

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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

2 classes of hair cell cilia

kinocilium (single)

stereocilia 20-300 (non-motile)