Neuroscience - Smell/taste

Question 1

what is olfaction

Answer 1

detection of airborne molecules

Question 2

what is gustation

Answer 2

information about ingested substances
chemical and physical qualities

Question 3

where are sensory receptors located

Answer 3

olfactory epithelium

Question 4

where do the olfactory afferent fibres project to

Answer 4

directly to the olfactory bulb in the CNS

Question 5

what are olfactory neurones

Answer 5

bipolar

Question 6

name structural features of the olfactory epithelium

Answer 6

unmyelinated sensory afferent
mucus layer
specialised cilia embedded in the mucus layer

Question 7

how long does olfactory neurone damage last for

Answer 7

6-8 weeks

Question 8

what produces the mucus in the olfactory lobe and what is its function

Answer 8

bowman’s gland
concentrates the chemicals and brings them into contact with the cilia

Question 9

what is the function of dividing stem cells in the olfactory epithelium

Answer 9

allow replacement of damaged olfactory neurones

Question 10

what are the G-proteins within olfactory cilia

Answer 10

G-olf

Question 11

what does odorant transduction lead to

Answer 11

cascade of chemical reactions leading to influx of Na+ and Ca2+ leading to depolarisation

Question 12

what does the olfactory receptor processes pass through

Answer 12

cribriform plate and enter the olfactory lobe

Question 13

how are different olfactory receptors selective for different odors

Answer 13

some GCPR’s are more receptive to some airborne chemicals than to others
may or not produce an action potential

Question 14

how are airborne chemicals distinguished from eachother

Answer 14

the pattern of of different types of olfactory neurones that do and don’t produce an action potential in the presence of the odor

Question 15

what is the olfactory bulb composed of

Answer 15

mitral cells - olfactory tract
glomeruli - convergence and amplification

Question 16

where do the axons of the mitral cell project

Answer 16

from the olfactory bulb to accessory olfactory nuclei

Question 17

the relationship between one odorant neurone and one glomeruli enables what

Answer 17

allows specific regions of the olfactory bulb to respond to different chemicals

Question 18

what is the major target of the lateral olfactory tract

Answer 18

piriform cortex

Question 19

what are the neurones in the pyriphorm cortex

Answer 19

pyramidal neurones - glutamatergic

Question 20

what are taste papilae

Answer 20

specialised invaginations on the surface of the tounge

Question 21

what are the different types of taste papilae

Answer 21

filiform papillae
fungiform papillae
circumvallate
follate papillae

Question 22

which taste papillae hast no taste buds associated with it

Answer 22

filiform papillae

Question 23

how many taste buds does the fungiform and circumvallate contain

Answer 23

fungiform - 3 on the apical side
circumvallate - 250 in the trench

Question 24

how are follate papillae organised and how many taste buds do the contain

Answer 24

into parallel ridges
600

Question 25

what is the function of microvilli on the tips of taste cells

Answer 25

increase the surface area that molecules can interact with that taste cells

Question 26

at the apical microvilli, what protein receptors detect what

Answer 26

ion channels - salt and sour/acids GPCR - sweet, bitter and umami

Question 27

where do the taste efferent neurones project to

Answer 27

the facial (VII) glossopharyngeal (IX) vagus (X)

Question 28

what are the transmitters involved in taste

Answer 28

serotonin and ATP

Question 29

what detects sweet and umami

Answer 29

T1 receptors

Question 30

what is the key secondary messenger in signalling for sucrose, glutamate and quinine

Answer 30

phospholipase beta 2

Question 31

outline the basic transduction of sweetness

Answer 31

detected by T1R2/T1R3 activation of PLC beta 2

Question 32

outline the basic transduction of umami

Answer 32

detected by T1R1/T1R3 activation of PLC beta 2

Question 33

what is the half maximal concentration of glutamate

Answer 33

0.3mM/L

Question 34

outline the basic signalling pathway for biterness

Answer 34

detected by T2R receptors expresses alpha-gustducin activation of PLC beta 2

Question 35

what nerves project from the tongue

Answer 35

cranial nerve VII - facial nerve and chorda tympani

Question 36

what nerves project from the back of the tongue

Answer 36

cranial nerve IX - lingual branch of the glossopharyngeal nerve

Question 37

what nerves project from the epiglottis and oesophagus

Answer 37

cranial nerve X - superior laryngeal branch of the vagus nerve

Question 38

where does cranial nerve VII project to

Answer 38

the rostral part of the gustatory nucleus

Question 39

where does cranial nerve IX project to

Answer 39

the mid region of the gustatory nucleus

Question 40

where does cranial nerve X project to

Answer 40

caudal region of the gustatory nucleus

Question 41

what is 2nd order signalling of gustation

Answer 41

from the gustatory nucleus to the ventral posterior medial nucleus (VPM)

Question 42

what is 3rd order signalling of gustation

Answer 42

signalling from the VPM to the gustatory cortex - insular and orbitofrontal cortex

Question 43

where in the higher centres of the brain is salt detected

Answer 43

insular cortex

Question 44

what is the function of the orbitofrontal cortex

Answer 44

gives us our perception of food involved in signalling for satiety