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Taste and Smell
N/A
27
Anatomy
Undergraduate 1
12/09/2008

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Cards

Term
What are the four categories of chemoreceptors in taste and smell?
Definition

1.visceral chemoreceptors

2.gustatory receptors

3.olfactory receptors

4.chemosensitive endings

Term
what three things is flavor a combination of?
Definition

1. direct chemical stimulation of taste buds on tongue

 

2. stimulation of olfactory receptors by vapours in food

 

3. stimulation of chemical receptors and somatosensory free nerve endings in mucous membranes of oral and nasal cavities

- impt for texture, spiciness, temperature, texture of food

Term
where are taste receptors located?
Definition
within taste buds
Term
what structures do taste buds sit on?
Definition
papillae
Term
what are the three kinds of papillae?
Definition

1. fungiform papillae

-200-300

-contains 3-5 taste buds

 

2.foliate papillae

-about 20 folds

-contain 100-150 taste buds

 

3.circumvallate papillae

-series of 8 or 9

-contain 250 taste buds

Term
what type of cells are taste receptors?
Definition
modified epithelial cells, but act like neurons
Term
what are the five taste sensations?
Definition

salty - cation channels

sour - cation channels

bitter - G protein-coupled receptors --> cation channels

sweet - G protein-coupled receptors --> cation channels

umami(glutamate) - G protein-coupled receptors --> cation channels

Term
how is the signal in taste receptor carried to neurons?
Definition
by depolarization
Term
which nerves transmit taste information?
Definition
CN VII, IX, X
Term
What structures does CN VII innervate?
Definition

soft palate via greater petrosal nerve

anterior 2/3 of tongue from chorda tympani nerve

Info goes to geniculate ganglion

Term
what structures does the CN IX innervate?
Definition

posterior 1/3 of tongue, tonsils and pharynx

info sent to inferior ganglion of IX (petrosal ganglion)

Term
what taste structures does the CN X innervate?
Definition

epiglottis

info sent to inferior ganglion of X (nodose ganglion)

Term
what is the solitary tract nucleus?
Definition

The solitary nucleus and tract are structures in the brainstem that carry and receive visceral sensation and taste from the facial (VII), glossopharyngeal (IX) and vagus (X) cranial nerves.

from Wikipedia

Term
where do secondary neurons from the solitary tract nucleus go?
Definition

1. reflex motor nuclei

-from there to muscles involved in swallowing, salivation, coughing

 

2. to ipsilateral VPM of thalamus

 

Term
where does information go after the VPM of thalamus?
Definition

1. central tegmental tract to gustatory cortex

includes:

insula

medial surface of frontal operculum

 

2. from gustatory cortex to orbital cortex, hypothalamus and amygdala

 

3.collaterals along central tegmental tract to reticular formation

Term
what are the sources of odourants detected by olfactory epithelium?
Definition

1. external environment through breathing or sniffing

2. vapours from food during eating (contributes to perception of flavour)

Term
how often are olfactory receptor cells replaced? and by what are they replaced?
Definition

1-2 months

by basal cells of olfactory epithelium

Term
what type of cells are olfactory receptors?
Definition
true neurons (bipolar)
Term
how are odourants detected?
Definition

olfactory vesicles have 10-30 immotile chemosensitive cilia

odourants diffuse in mucous or are bound to odourant-binding proteins with the mucous

axons of olfacotry receptors (unmyelinated) bundle into olfactory filia which pass through cribiform plate of ethmoid bone

Term
how man different olfactory receptor neurons do we have?
Definition
300
Term

what kind of receptors are olfactory receptors?

Definition

GPCR

2nd messenger system results in depolarization (CA2+, NA+, K+ influx, Cl- efflux)

receptor potential adapts --> fading perception of odours

Term
what cell types are seen in olfactory bulb?
Definition

1. mitral cells

2. granule cells

3. tufted cells

Term
how are axons of the same receptor types organised?
Definition
they are organised into specific glomeruli
Term
what do mitral and tufted cells give collaterals to?
Definition

1. anterior olfactory nucleus

2. olfactory tubercle

3. PIRIFORM CORTEX

4. part of amygdala

5. periamygdaloid cortex

6. part of entorhinal cortex

Term
where do projections of primary olfactory cortex go?
Definition

1. hypothalamus

2. hippocampus

3. amygdala

4. thalamus

– dorsomedial nucleus connects

olfactory bulb to olfactory

association cortex (anterior

insula adjacent to gustatory

cortex)

5. directly to association cortex

6. orbital cortex

Term
where is the association cortex for flavor located?
Definition
the orbital cortex
Term

the association cortex for flavour recieves what kinds of inputs?

 

Definition

1. gustatory

2. somatosensory

3. olfactory

4. visual

5. limbic

• all can modulate flavour

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