Olfaction & Taste

Question 1

___ contains odorant receptor neurons

Answer 1

superior portion of nasal cavity

Question 2

Smell starts w/ ___

Answer 2

odorants

Question 3

ORNs are ___ neurons w/ special sensory cilia. When are they replaced?

Answer 3

Bipolar
Regular basis

Question 4

Odorants bind to ___ in the ___ & it sends ___ up their axons through ___ to ___

Answer 4

odorant receptors
in the mucus (where olfactory cilia are)
AP
cribriform plate
synapse on olfactory bulb

Question 5

Odorant receptors are ___ receptors

Answer 5

G protein coupled

Question 6

Olfactory signals connect to ___ & ___

Answer 6

the limbic system & the cortex

Question 7

The olfactory bulb first targets limbic structure centers involved in

Answer 7

emotion, reward & memory

Question 8

What is the pathway for olfaction?

Answer 8

Primary (1) = olfactory receptors travels down the olfactory nerve & synapse on olfactory bulb
Secondary (2) = olfactory bulb travels down the olfactory tract
Tertiary (3*) = olfactory bulb targets limbic structures

Question 9

What are the following limbic structures responsible for?
Piriform cortex
Entorhinal cortex
Hippocampus
Hypothalamus
Amygdala

Answer 9

Piriform cortex - olfaction
Entorhinal cortex - memory & association
Hippocampus - learning & memory
Hypothalamus - autonomic responses & appetite
Amygdala - emotion

Question 10

Define hyposmia

Answer 10

reduced ability to detect odors

Question 11

Define anosmia

Answer 11

complete inability to detect odors

Question 12

Define parosmia

Answer 12

change in the normal perception of odors

Question 13

Define phantosmia

Answer 13

sensation of an odor that isn’t there

Question 14

What are causes of changes in smell?

Answer 14

• Anything that prevents odors from getting to the odorant receptors
• loss of disruption in smell signaling (aging & mental illness)
• congenital anosmia

Question 15

Cause of loss of smell w/ age

Answer 15

olfactory receptor numbers & olfactory bulb fibers decrease w/ age

Question 16

Mental illnesses that result in change in smell

Answer 16

Hyposmia & phantosmia can be associated w/ early stages of Alheimers disease, Parkinsons, schizophrenia, & other types of dementia
Mood disorders may also be associated w/ changes in smell

Question 17

3 kinds of papillae on tongue that have taste buds

Answer 17

• Circumvallate papillae
• Foliate papillae
• Fungiform papillae

Question 18

What other locations have taste buds?

Answer 18

Epiglottis & hard palate

Question 19

T/F: Only certain parts of your tongue have taste buds for certain tastes

Answer 19

F
All parts of tongue have taste buds for all of taste

Question 20

Taste buds are located ___

Answer 20

on the side of papillae

Question 21

What’s the first cell in taste receptor pathway?

Answer 21

Gustatory Receptor

Question 22

Taste cells release neurotransmitters, what are they?

Answer 22

serotonin (5-HT), ATP, & GABA (an inhibitory)

Question 23

G-protein coupled receptor or ion channel receptors for the following:
Salt
Acids
Sweet/umami
Bitter

Answer 23

Salt & acids = ion channels
Sweet/umami & bitter = G protein coupled receptors

Question 24

CN for anterior part of tongue, side of tongue, back of tongue, epiglottis & hard palate

Answer 24

CN VII innervates anterior part of tongue
CN IX innervates side & back of tongue
CN X innervates epiglottis
CN VII innervates hard palate

Question 25

Taste pathway

Answer 25

1st neuron = taste buds in CN VII, IX, or X
2nd neuron = nucleus of solitary tract in brainstem
3rd neuron = ventral posterior medial (VPM) of thalamus
4th neuron = gustatory cortex in the insula

Question 26

Define ageusia

Answer 26

loss of taste

Question 27

Define dysgeusia & parageusia. What may be its cause?

Answer 27

abnormal or distorted taste

Antibiotics
Chemotherapy or radiation
Gingivitis or caries
Zinc deficiency

Question 28

Define hypogeusia

Answer 28

decreased taste sensitivity

Question 29

Define hypergeusia

Answer 29

increased taste sensitivity

Question 30

Define sensory loss

Answer 30

disruption of sensory perception machinery that creates signals

Question 31

Define neural loss

Answer 31

damage to or loss of the nerves that carry sensory signals

Question 32

Define xerostomia. What can it cause?

Answer 32

dry mouth
Lack of saliva due to dissolve testants & deliver them to taste buds

May cause hypogeusia

Question 33

Does the trigeminal (CN V) contribute to taste?

Answer 33

NO

It only provides signals that can modify sense of taste (like cold, spiciness & astringent)