Smell and taste

Question 1

chemical senses

Answer 1

are the oldest and most common form of sense

Question 2

function of chemical sense

Answer 2

identify food sources
avoid noxious substances
find a mate or mark territories

Even bacteria can sense chemical (chemotaxis)
Primitive function
Eg dogs use pheromones to detect a mate

Question 3

gustatory system and olfactory system differences

Answer 3

have separate transduction mechanisms
information is processed in parallel
information is merged in the CNa

Question 4

5 basic tastes

Answer 4

salty 
sour
sweer
bitter
umami

Question 5

salty

Answer 5

vital electrolytes, ionotropic receptor

Question 6

sour

Answer 6

acids, H+ inotropic receptors - fatty acids

Question 7

sweet

Answer 7

innante fondess, high energy foods, metabotropic receptors (g protein coupled)

Question 8

bitter

Answer 8

instinctively rejected, often poisonous, metabotropic receptor

Question 9

umami

Answer 9

delicious in japanese
savoury taste of GLUTAMATE (excitatory neurotransmitter, and amino acid for protein, metabotropic receptor (MSG in fast foods)

Question 10

perception of flavour

Answer 10

mixture of the receptors activates

and receptors for texture and temperature receptor

Question 11

craving

Answer 11

when deficit in nutrients

Question 12

where taste smell touch combined

Answer 12

in the cortex

Question 13

correct concs of sodium and potassium is really important

Answer 13

will crave salty foods if not enough sodium in body

Question 14

lingual papillae

Answer 14

taste-sensing strutures

lumpy structures of tongue

Question 15

taste organs

Answer 15

tongue, cheeks, soft palate, pharynx, epiglottis

Question 16

most sensitive flavours

Answer 16

sour and bitter

Question 17

4 types of lingual papillae

Answer 17

filliform
foliate
fungiform
circumballate

Question 18

filliform

Answer 18

spiked, no taste buds, sense texture, most abundant

Question 19

foliate

Answer 19

ridges, least abundant, gone by 2-3 years

Question 20

fungiform

Answer 20

mushrooms, mainly at sides and front

Question 21

circumvallate

Answer 21

pimples, large, contain about half of all taste buds

Question 22

taste buds contain

Answer 22

taste cells and gustatory afferents

Question 23

number of taste buds

Answer 23

2000-5000

about 100 taste cells per taste bud

Question 24

taste pores

Answer 24

allows stimulus detection by micro villi

Question 25

gustatory afferents carry

Answer 25

information to central nervous system

Question 26

papillae have

Answer 26

pores where stimulus enters | side of papillae is where taste bud sits

Question 27

taste cells

Answer 27

become thin at apex, projecting into taste pore, transducer stimuli into electrical signal

Question 28

basal cells

Answer 28

like stem cells, renew taste cells every 2-3 weeks

Question 29

bitter, sweet, umami transduction mechanism

Answer 29

similar systems (just slightly different receptors but all g protein coupled receptors) metabotropic no synaptic vesicles uses ATP 1) Activation of g protein coupled receptor 2) Activate PLCB2 3) And then iP3 4) Ca released from intracellular stores 5) TrpM5 opens and allows sodium and calcium to enter cell\ 6) Sodium moving in causes depolarisation in taste cell 7) VGNC (voltage gated sodium channel) opens causing depolarisation further 8) Release of neurotransmitter at base of cell – ATP is acting as the neurotransmitter 9) ATP moves out of channel

Question 30

sour transduction mechansism

Answer 30

ionotropic synaptic vesicles uses 5-HT, GABA, ATP 1) Ion channels at apical tips permeable to hydrogen ions 2) Already depolarising the cell (so the stimuli itself is already starting the process of depolarisation) 3) Opening of VGNC further depolarisation 4) Activating VGCC (calcium channels) allow calcium into cell 5) Activates the release of synaptic vesicles – a variety of neurotransmitters in vesicles : HT, GABA, ATP

Question 31

taste cells threshold

Answer 31

they have different threshold for different basic tastes- 'preferences' e.g. gustatory axons labelled red receive most inputs from taste cells that respond best to sucrose (sweet), but they also receive input from taste cells that respond to other basic tastes One taste cell can respond to sweet and salty stimuli for example, but will respond best to one of these stimuli, as it will be detected at a lower threshold.

Question 32

Gustatory afferents from anterior 2/3rds of tongue are carried in

Answer 32

facial nerve, cranial nerve VII.

Question 33

logistics of specific taste receptors

Answer 33

We cannot have a completely specific labelled line code, otherwise every flavour would need a specific taste receptor – we don’t have enough proteins for that. So we need to combine the responses of many gustatory afferents using population coding.

Question 34

odorants

Answer 34

detected as low as a few parts per trillion must dissolve in the music later to reach olfactory cells can't detect chemicals in the air cavity behind the nose that sense smells

Question 35

the olfactory receptors re

Answer 35

on the cilia that protect mucsus where the adroitness are dissovled Axons (thin and unmyelinated) will form cranial nerve I (olfactory nerve) Basal cells help produce new olfactory neurons (newly made in adults in humans)

Question 36

transduction occurs via specific g-protein coupled receptors

Answer 36

all odorant receptors are g protein coupled every one uses the same downstream pathway When G (olf) activated, Activate somethhing clycalse and then cAMP Which opens other ion channels (CNG- cyclic neuclotide gated channel) Sodium and potassium – graded potential in cilia (dendrite part) ANO2 allows cholride into and out of cell Further depolarisation of Cl moving out

Question 37

anosmic

Answer 37

Golf knock out mice are anosmic i.e. they cannot smell.

Question 38

odorant receprotr protein genes comprise how much of the entire genome

Answer 38

about 3-5 %

Question 39

Graded receptor potential Enough of odorant around to enough of a potential Produces spikes of AP if above threshold

Answer 39

Large enough receptor potential = threshold for action potential firing reached Intense stimulus = large receptor potential = increased action potential firing rate

Question 40

glomerulus of olfactorybulb

Answer 40

received input from the olf receptor cells expressing one specific olf receptor second order neutron carry info from the glomeruli to various regions of the brain

Question 41

olfactory projections - conscious smell

Answer 41

conscious smell- olfacotry cortex

Question 42

olfactory memory

Answer 42

hippocampus

Question 43

emotional responses

Answer 43

amygdala

Question 44

visceral responses

Answer 44

reticular formation

Question 45

sex & neuroendocrine

Answer 45

hypothalamus

Question 46

which sensory cells release ATP via ion channels rather than synaptic vesicles

Answer 46

taste cells responsive to bitter, umami and sweet ion channel called calcium homeostasis modulator 1 (CALMH1) when they are stimulated. CALMH1 is a voltage-gated ion channel that opens as the taste cells depolarise in the sequence of downstream events that occur following the activation of G-protein coupled receptors by bitter, sweet or umami stimuli.

Question 47

which sensory cells use synaptic vesicles

Answer 47

sour and potentially salty stimuli don't use g protein coupled receipts instead depolarise due to activation of ion channels - traditional method of synaptic vesicle fusion to release their neurotransmitter onto the primary afferent heron when they depolarise