Physiology: Sense Of Smell & Taste

Front 1

_____________ is the ability of an organism to sense and identify a substance by detecting trace amounts that evaporate.

Back 1

Smell

Front 2

Based on sense of smell, animals are classified into :

Back 2

•Microsmatic (poorly developed sense of smell). Eg Human

•Macrosmatic animals (highly developed sense of smell). Eg Dog

Front 3

Sense of smell influences social and sexual behaviour especially in macrosmatic animals. T/f

Back 3

True

Front 4

Olfactory system consists of ;

Back 4

Nose (olfactory epithelium and olfactory nerve),

Olfactory Bulb

Olfactory Tract

Olfactory Cortex

NBTC

Front 5

Define Olfactory pathway

Back 5

The olfactory pathway is the interneuronal connection from olfactory epithelium to the brain for olfactory signal transduction.

Front 6

Discuss the olfactory pathway

Back 6

Axons of olfactory receptor cells projects through the cribriform plate of ethmoidal bone as olfactory nerve. Olfactory nerves converge to synapse with dendrites of cells mitral and tuft cells within the glomeruli of the olfactory bulb. Axons of mitral and tuft cells forms the olfactory tract which projects from the olfactory bulbs to the brain in two pathways; lateral and medial olfactory stria. The lateral olfactory stria synapses in the primary olfactory cortex, which includes the prepiriform cortex and hippocampus. The lateral olfactory stria also projects through the thalamus to the orbitofrontal cortex. The medial olfactory tract projects to the septal nuclei to hypothalamus.

Front 7

__________ are area closely associated with identification of odor

Back 7

Piriform cortex :

Front 8

_____________ is responsible for the emotional responses to olfactory stimuli, it is involved in social functions such as mating and recognition of animals of the same species.

Back 8

Amygdala

Front 9

____________ is concerned with olfactory memories.

Back 9

Entorhinal cortex :

Front 10

_______________ functions in Conscious perception of smell

Back 10

Orbitofrontal cortex :

Front 11

_______________ is the process by which an odorant binds to its receptor to generate action potential.

Back 11

Olfactory signal transduction

Front 12

The olfactory receptors are ;

Back 12

G protein.

β and γ coupled receptors (with subunits located on the cilia of the olfactory neurons).

Front 13

When an odorant molecules binds to the olfactory receptor, the G protein subunits ____________.

Back 13

Dissociate

Front 14

When an odorant molecule binds to the olfactory receptor ,what happens?

Back 14

When an odorant molecules binds to the olfactory receptor, the G protein subunits dissociate. Then the α-subunit activates adenylate cyclase Adenylyl cyclase catalyses the conversion of ATP to cAMP. cAMP acts as a second messenger to opening Na + /Ca 2+ Influx of Na + and Ca 2+ channels. produces depolarization of the olfactory neuron generating action potential that is propagated along the olfactory nerve to the olfactory bulb and to olfactory cortex.

Front 15

Olfactory dysfunctions refers to abnormality of smell. It can be _____________ or _____________

Back 15

Quantitative or Qualitative

Front 16

______________ refers absence or alteration in intensity of smell perception.

Back 16

Quantitative olfactory dysfunction

Front 17

List the types of Quantitative olfactory dysfunction

Back 17

•Anosmia

•Hyposmia

•Hyperosmia

Front 18

__________ is the absence of smell sensation.

Back 18

Anosmia

Front 19

___________ means decreased smell sensation.

Back 19

Hyposmia

Front 20

___________ means Exaggerated smell sensation.

Back 20

Hyperosmia

Front 21

_________________ refers to distortion in smell perception.

Back 21

Qualitative olfactory dysfunction.

This is referred to as Dysosmia

Front 22

Mention the types of Qualitative olfactory dysfunction

Back 22

•Parosmia ( troposmia )

•Phantosmia

Front 23

What is Phantosmia?

Back 23

This is the sensation of an odour that isn't there.

Front 24

Phantosmia is otherwise called_______________

Back 24

Olfactory Hallucination

Front 25

____________ is referred to as change in the normal perception of odours, such as when the smell of something familiar is distorted or when something that normally smells pleasant now smells foul.

Back 25

Parosmia (troposmia)

Note: the natural pleasant odour of a substance is perceived to be offensive or foul.

Front 26

Primary sensation of smell include;

Back 26

1. Camphoraceous

2. Musky - musk

3. Floral - roses

4. Pepperminty – mint

5. Ethereal - eucalyptus

6. Pungent - pears vinegar

7. Putrid - rotten eggs

Front 27

The sensory system coordinating taste sensation is called the _______________ .

Back 27

Gustatory system

Front 28

The ____________ is a brain structure responsible for the perception of taste.

Back 28

Primary gustatory cortex

Front 29

Primary gustatory cortex include;

Back 29

•Anterior Insula (on the insula lobe)

•Frontal operculum (on the inferior frontal gyrus of the frontal lobe)

Front 30

Papillae are located on the tongue. The 4 major papillae are;

Back 30

•Circumvallate

•Foliate

•Fungiform

•Filiform (smallest and most numerous, located mainly at centre of the tongue)

Front 31

All papillae have taste bud except ________

Back 31

Filiform papillae

Front 32

All papillae have taste bud except ________

Back 32

Filiform papillae

Some taste buds are also be found on the palate and pharynx.

Front 33

___________________ is the process by which a tastant binds to its receptor to generate action potential.

Back 33

Taste signal transduction

Front 34

Salty and sour taste sensations are both detected through _____________ .

Back 34

ion channels

Front 35

Sweet, bitter, and umami tastes, however are detected by way of _____________

Back 35

G protein coupled with taste receptors

Front 36

Salt is perceived in the mouth through the salt (NaCl) receptor and sodium ion channel in the taste cell wall. T/f

Back 36

True

Front 37

The sodium ion channel is known as _____________

Back 37

Epithelial Na Channel (ENaC)

Front 38

ENaC is composed of three subunits and can be blocked by ___________.

Back 38

Amiloride

Front 39

ENaC allows Na + ions to enter the cell resulting in signal transduction culminating in perception of salty taste. T/f

Back 39

True

Front 40

There are three different receptor proteins at work in sour taste;

Back 40

ENaC : which allows hydrogen ions to flow directly into the cell.

H + gated K + channel : ordinarily allows K+ ions to escape from the cell. H+ ion blocks these, trapping the pattasium ion inside the cell.

Ca 2+ channel : This third protein opens to Na + ions when a hydrogen ion attaches to it, allowing the sodium ions to flow down the concentration gradient into the cell. The influx of ions leads to the opening of a voltage regulated Ca 2+ gate.

NB

These receptors work together and lead to depolarization of the cell and neurotransmitter release.

Front 41

Bitter taste is perceived by __________________ in the taste cell walls

Back 41

G protein coupled receptors (GPCR).

Front 42

When the bitter compound activates the GPCR, it in turn releases ___________

Back 42

Gustducin

Front 43

Gustducin is made of three subunits which upon activation break apart and activate phosphodiesterase resulting in destruction of cAMP. T/f

Back 43

True

Front 44

Decrease in cAMP closes potassium ion channels. T/f

Back 44

True

This culminates in depolarization and signal transduction.

Front 45

Sweet tastant , such as sucrose activates the G-protein, gustducin, which in turn activates ___________.

Back 45

Adenylate cyclase

Adenylate cyclase catalyzes the conversion of ATP adenosine 3',5'to cyclic monophosphate (cAMP) cAMP molecule activates a protein kinase, which in turn phosphorylates and closes a potassium ion channel. Intracellular increase in potassium ions cause calcium ion channels to open, further depolarizing the cell resulting in neurotransmitter release and action potential propagated to the primary afferent neuron.

Front 46

____________ is the term that identifies the taste of substances such as l- glutamate

Back 46

Umami

Front 47

Umami was discovered in ________ by _________, a Professor of the Tokyo Imperial University.

Back 47

1908

Kikunae Ikeda

Front 48

The amino acid Lglutamate bonds to a type of GPCR known as a metabotropic glutamate receptor (mGluR4). This causes the Gprotein complex to activate a secondary receptor resulting in signal transduction. T/f

Back 48

True

Front 49

__________ means absense of the sense of taste

Back 49

Ageusia

Front 50

________ means diminished taste sensitivity.

Back 50

Hypogeusia

Front 51

___________ means unpleasant perception of taste in this condition a foul or metallic taste sensation persists in the mouth.

Back 51

Dysgeusia/Parageusia.