Smell and Taste

Question 1

what receptors are smell and taste forms of?

Answer 1

chemoreception

Question 2

where are the olfactory receptors found

Answer 2

in the olfactory epithelium (at the top of the nose)

Question 3

how many receptors cells does the epithelium contain

Answer 3

10 million receptor cells and covers 3 cm squared in each side

Question 4

what colour is our epithelium

Answer 4

pale yellow

Question 5

ciliated neurons

Answer 5

single dendrite that extends into the olfactory epithelium

Question 6

nonmotile cilia

Answer 6

the receptors neurons branches to form nonmotile cilia that. increase the surface area of cell so it has greater chance of catching odorant’s

Question 7

how many kinds of odorant receptors do we have

Answer 7

400

Question 8

how many g coupled protein receptors genes do we have

Answer 8

1000 or 3-5% of the genome, but only 400 are expressed in humans

Question 9

what happens when odorant molecule binds to its receptors

Answer 9

it will bind to its receptor G(olf) which increases the concentration of cAMP. cAMP gated channels open, depolarizing the neurons and triggering an action potential that travels to the olfactory bulb

Question 10

how many cells must react before we experience a smell

Answer 10

40 cells

Question 11

Properties of olfactory receptor cells

Answer 11

pinocytotic, continually sipping in fluid and sending it along the nerves into the brain

short lived, degenerating after a month or 2 that will be replaced by new ones

Question 12

olfactory bulb

Answer 12

extension of the cerebrum and lies on the underside of the frontal lobes

Question 13

olfactory nerve

Answer 13

projection from the receptors to the bulb

Question 14

convergence in olfactory receptors

Answer 14

many receptor cells converge on each bulb neuron

Question 15

how does our smell pathways bypass the thalamus

Answer 15

the bulb projects directly to the olfactory cortex

Question 16

where is the olfactory cortex located?

Answer 16

in the frontal and temporal lobe

Question 17

where else does the bulb project to? wHy?

Answer 17

limbic system. because evolutionarily smell was tied to motivation

Question 18

pheromones

Answer 18

chemicals released by an animal into the environment which affect the physiology or behaviour of other members of its species

Question 19

what do rats have in their nasal cavity that is involved in their behavioural responses to sex pheromones

Answer 19

Vomeronasal organ (VNO)

Question 20

where are our main taste receptor cells

Answer 20

in taste buds on our tongue

Question 21

how many taste buds do we have? How are they distributed

Answer 21

5000. mainly on the top of the tonguee but also on the soft palate, epiglottis and upper esophagus

Question 22

how many taste buds do babies have

Answer 22

10,000

Question 23

how many receptor cells does each bud have

Answer 23

100- epithelial cells

Question 24

how many kinds of receptor does a typical taste bud contain

Answer 24

sweet and umami cells: detect sugar and glutamate (protein)
bitter: poison
salty and sour: detect Na and H
receptor for fatty acids

Question 25

three types of taste receptor cells

Answer 25

Type 1 sense salt
Type 2 cells release ATP which act on neurons and type 3 cells- can sense sweet, Bitter, and umami
type 3 form synapses with sensory neurons, activating them with serotonin

Question 26

what G protein coupled receptor do cells for sweet umami and Bitter couple to

Answer 26

glustduci, which activates pathways increasing calcium and ATP release

Question 27

why aren’t detection of salt and sour linked with G proteins

Answer 27

because they involve G proteins

Question 28

is our experience with food dependent entirely on our taste buds

Answer 28

no it depends on smell, temperature, pain, texture, crunch, and appearance and cognition

Question 29

what channels do the nerve endings in the walls of the mouth have

Answer 29

TRP channels that are sensitive to temperature and chemicals,

Question 30

what nerves do receptor cells in the taste bud excite

Answer 30

cranial nerves 7, 9, and 10, glossopharyngeal and vagus nerves

Question 31

where do those cells synapse to

Answer 31

they snaps in medulla and thalamus en route to cortex

Question 32

what cranial nerve do TRP receptors in the walls of the mouth excite

Answer 32

5, the trigeminal