Chemosensation Flashcards
a loss of smell is called _____
anosmia
a loss of taste is called ______
ageusia
what is usually called a “taste” sensation involves stimulation of three sensory systems: _______
olfaction (smell),
gustation (taste proper),
chemesthesis (detection of irritant chemicals by trigeminal nerve endings)
what are examples of irritant or noxious stimuli detected my chemesthesis
capsaicin (main irritant component of chili peppers)
CO2 (carbonated beverages),
mints,
mustard or vinegar [acetic acid]
what is the vomeronasal system?
a system that detects pheromones, which are chemical signals that communicate social and
sexual information
which cranial nerves are involved in taste?
VII, IX, X
describe the receptor cell for smell
Ciliated, bipolar neuron
what is the Primary Sensory Nucleus in CNS for taste?
Nuc. of the Solitary Tract
describe the receptor cell for CHEMESTHESIS
Free Nerve Ending of Cranial Ganglion Cell
which cranial nerve is involved in CHEMESTHESIS
CN V (mostly)
Fungiform, vallate and foliate papillae house taste buds; ________ do not.
filiform
The majority of taste buds in humans are on the tongue, but we have numerous taste buds on the _______.
soft palate, oropharynx,
and epiglottis
Lingual taste buds lie on specialized bumps
or grooves, called taste ______
papillae
_____ papillae are located on the sides of the tongue
foliate
fungiform papillae are located all over the ______ end of the tongue,
anterior
________ papillae at the posterior part of the
tongue.
circumvallate
The ________ branch of the facial nerve innervates fungiform taste papillae in the anterior 2/3 of the tongue.
chorda tympani
the _______ nerve innervates the circumvallate
papillae.
glossopharyngeal
Taste buds located in the soft palate are innervated by the ________ branch of the facial nerve.
superior petrosal
The taste buds in the extreme posterior tongue, oropharynx and epiglottis are supplied by the _______.
vagus
Drugs that block _______ receptors (to relieve pain) can cause loss of taste, which can limit patient
compliance with these treatments.
P2X3
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
________.
PROP (Propylthiouracil)
people who are unable to detect PROP have a higher incidence of _________
respiratory bacterial diseases
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)
ipsilateral
name the receptor type for each taste
salty, sweet, sour, bitter, umami
salty: Ion channel
sour: Ion channel
Sweet: GPCR
bitter: GPCR
Umami: GPCR
The NST relays taste information to the ________ for regulation of food intake and for visceral reactions to ingested foods
hypothalamus and amygdala
NST has reflex connections to nuclei in the brainstem involved in gagging e.g.(________ ), swallowing
(e.g.___________) and salivation (e.g.__________).
nuc. ambiguus,
nuc. ambiguus, hypoglossal nuc,
sup. & inf. Salivatory nuc.
__________ neurons are the only neurons that are continuously undergoing replacement by neurogenic basal cells
olfactory
describe olfactory transduction
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
olfactory receptor proteins also serve as chemoreceptors outside of the olfactory system.
Examples of tissues exhibiting functional olfactory receptors include ________ & __________.
kidney,
lung
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.
orthonasally,
retronasally
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.
glomeruli
The axons of output cells from the olfactory bulb collect into the _________ tract.
lateral olfactory
The olfactory cortex consists of the _______ and part of the uncus.
lateral olfactory gyrus
the primary principle of encoding odor quality is through a odor-related map of _______in the olfactory bulb.
glomeruli
