Chemosensation

Question 1

a loss of smell is called _____

Answer 1

anosmia

Question 2

a loss of taste is called ______

Answer 2

ageusia

Question 3

what is usually called a “taste” sensation involves stimulation of three sensory systems: _______

Answer 3

olfaction (smell),
gustation (taste proper),
chemesthesis (detection of irritant chemicals by trigeminal nerve endings)

Question 4

what are examples of irritant or noxious stimuli detected my chemesthesis

Answer 4

capsaicin (main irritant component of chili peppers)
CO2 (carbonated beverages),
mints,
mustard or vinegar [acetic acid]

Question 5

what is the vomeronasal system?

Answer 5

a system that detects pheromones, which are chemical signals that communicate social and
sexual information

Question 6

which cranial nerves are involved in taste?

Answer 6

VII, IX, X

Question 7

describe the receptor cell for smell

Answer 7

Ciliated, bipolar neuron

Question 8

what is the Primary Sensory Nucleus in CNS for taste?

Answer 8

Nuc. of the Solitary Tract

Question 9

describe the receptor cell for CHEMESTHESIS

Answer 9

Free Nerve Ending of Cranial Ganglion Cell

Question 10

which cranial nerve is involved in CHEMESTHESIS

Answer 10

CN V (mostly)

Question 11

Fungiform, vallate and foliate papillae house taste buds; ________ do not.

Answer 11

filiform

Question 12

The majority of taste buds in humans are on the tongue, but we have numerous taste buds on the _______.

Answer 12

soft palate, oropharynx,

and epiglottis

Question 13

Lingual taste buds lie on specialized bumps

or grooves, called taste ______

Answer 13

papillae

Question 14

_____ papillae are located on the sides of the tongue

Answer 14

foliate

Question 15

fungiform papillae are located all over the ______ end of the tongue,

Answer 15

anterior

Question 16

________ papillae at the posterior part of the

tongue.

Answer 16

circumvallate

Question 17

The ________ branch of the facial nerve innervates fungiform taste papillae in the anterior 2/3 of the tongue.

Answer 17

chorda tympani

Question 18

the _______ nerve innervates the circumvallate

papillae.

Answer 18

glossopharyngeal

Question 19

Taste buds located in the soft palate are innervated by the ________ branch of the facial nerve.

Answer 19

superior petrosal

Question 20

The taste buds in the extreme posterior tongue, oropharynx and epiglottis are supplied by the _______.

Answer 20

vagus

Question 21

Drugs that block _______ receptors (to relieve pain) can cause loss of taste, which can limit patient
compliance with these treatments.

Answer 21

P2X3

Question 22

Individual differences in primary structure of the receptor proteins (polymorphisms) can lead to different degrees of sensitivity to particular taste substances. The most common example is differential sensitivity to
________.

Answer 22

PROP (Propylthiouracil)

Question 23

people who are unable to detect PROP have a higher incidence of _________

Answer 23

respiratory bacterial diseases

Question 24

Primary afferents from the tongue run in the facial (VII), glossopharyngeal (IX) and vagus (X) nerves. When these axons enter the CNS they synapse on second order neurons in the rostral area of the _______ nucleus of the solitary tract (NST)

Answer 24

ipsilateral

Question 25

name the receptor type for each taste

salty, sweet, sour, bitter, umami

Answer 25

salty: Ion channel
sour: Ion channel
Sweet: GPCR
bitter: GPCR
Umami: GPCR

Question 26

The NST relays taste information to the ________ for regulation of food intake and for visceral reactions to ingested foods

Answer 26

hypothalamus and amygdala

Question 27

NST has reflex connections to nuclei in the brainstem involved in gagging e.g.(________ ), swallowing
(e.g.___________) and salivation (e.g.__________).

Answer 27

nuc. ambiguus,
nuc. ambiguus, hypoglossal nuc,
sup. & inf. Salivatory nuc.

Question 28

__________ neurons are the only neurons that are continuously undergoing replacement by neurogenic basal cells

Answer 28

olfactory

Question 29

describe olfactory transduction

Answer 29

odorant binds to the receptor protein > associated G-protein (Golf) activates adenylate cyclase >
increase in cAMP > opens a nearby cAMP-gated ion channel > influx of Na+ and Ca2+.> The local increase in Ca2+ opens adjacent Ca2+-gated Chloride channels.> efflux of Cl- > further depolarizing the cell > AP

Question 30

olfactory receptor proteins also serve as chemoreceptors outside of the olfactory system.
Examples of tissues exhibiting functional olfactory receptors include ________ & __________.

Answer 30

kidney,

lung

Question 31

The olfactory epithelium can be stimulated
either ______, i.e. by odors entering the nostril, or
_______, i.e. by odors from substances in the mouth
which curve backward past the soft palate the enter the nasal cavity from the rear.

Answer 31

orthonasally,

retronasally

Question 32

Axons of the olfactory neurons penetrate the ethmoid bone (cribriform plate) and converge on _____, which are spherical neuropil structures (a tangle of axons and
dendrites) present at the outer layer of the olfactory bulb.

Answer 32

glomeruli

Question 33

The axons of output cells from the olfactory bulb collect into the _________ tract.

Answer 33

lateral olfactory

Question 34

The olfactory cortex consists of the _______ and part of the uncus.

Answer 34

lateral olfactory gyrus

Question 35

the primary principle of encoding odor quality is through a odor-related map of _______in the olfactory bulb.

Answer 35

glomeruli