5. Chemical senses II Flashcards
(23 cards)
What are the four types of taste papillae found on the tongue?
fungiform, foliate, circumvallate, and filiform
Where are taste buds located?
in troughs around papillae (except filiform)
List the five basic tastes.
- bitter
- sour
- sweet
- salty
- umami
Which type of taste compounds are we most sensitive to?
bitter compounds
How does taste sensitivity compare to olfaction?
less sensitive
What is the turnover rate for taste cells?
every 6-8 weeks
What types of receptors are involved in taste sensation?
- Ion channels (for salty and sour)
- G-protein coupled receptors (for sweet, bitter, and umami)
What is the role of the T1R family in taste?
for sweet and umami (hetero-dimers)
What is the role of the T2R family in taste?
for bitter
What is the mechanism of direct depolarization for salty and sour tastes?
Ions directly enter cells through channels
What channels are involved in salty taste?
Amiloride-sensitive sodium channels
What channels are involved in sour taste?
TRPM5 channels and blocked potassium channels
Describe the indirect depolarization mechanism for sweet, bitter, and umami tastes.
GPCRs activate signaling cascades leading to calcium release
What pathway is activated in the signaling mechanism for sweet and umami tastes?
Phospholipase C β2 pathway
What neurotransmitters do taste cells release?
- serotonin
- ATP
Which cranial nerve carries taste information from the anterior 2/3 of the tongue?
Facial nerve (VII)
Which cranial nerve carries taste information from the posterior 1/3 of the tongue?
Glossopharyngeal nerve (IX)
Which cranial nerve carries taste information from the epiglottis and esophagus?
Vagus nerve (X)
Where do first-order neurons synapse in the taste pathway?
gustatory nucleus (nucleus tractus solitarius)
What is the final destination of taste signals after the thalamus?
- Insular cortex (primary taste center)
- Orbitofrontal cortex (secondary taste center)
- Amygdala and hypothalamus
What coding mechanism does taste use?
labeled line coding
What is the function of the orbitofrontal cortex in relation to taste?
integrates multiple sensory inputs for overall food perception
True or False: The orbitofrontal cortex is involved in satiety.
True
