1 D: Gustation Flashcards
What have studies shown regarding our taste buds?
We can distinguish between 4000-10,000 diff chemicals and 4-5 primary taste qualities.
What are the 4-5 taste qualities?
1) Salty (NacL)
2) Sweet (Sucrose)
3) Sour ( HCL or citric acid)
4) Bitter ( Quinine hydrochloride QHCL)
5) Umami ( glutamate; MSG)
What is a taste bud?
Taste receptor cells “Taste cells” located within clusters of cells known as TASTE BUDS
Where are taste buds found?
Upon the papillae located over the 1) Tongue 2) palate
3) pharynx 4) epiglottis
What are Fungiform Papillae like?
- Mushroom-like
- Scattered over ENTIRE TONGUE SURFACE, but most abundant at the TIP & along its ANTERIOR SIDES
What do Fungiform Papillae respond to?
**Sweet & **salty substances but also sour.
What are Foliate (edges) Papillae like?
- Folded structures
- Most abundant on the MIDDLE edges of the tongue
What do Foliate Papillae respond to?
MAINLY SOUR
What taste buds are innervated by the chorda tympani brach of CN 7 ( anterior 2/3 of the tongue) ?
**Fungiform papillae & some of the Foliate papillae
What are Circumvallate Papillae like?
- LARGEST and LEAST NUMEROUS
- Form an inverted V shape at the back of tongue
What do Circumvallate Papillae respond to?
BITTER substances
What taste buds are innervated by the glossopharyngeal CN 9 ( posterior 1/3 of the tongue) ?
***Taste buds on the CIRCUMVALLATE and some Foliate papillae
What are the taste buds in the region of the epiglottis supplied by?
CN 10 ( vagus)
What are the taste buds in the region of the palate are supplied by?
CN 7 ( Facial)
What is the myth of Taste Buds?
That it is specific to a certain location (i.e sweet is the tip), “tongue map” not entirely true.
***Taste stimuli are spread relatively equally across the tongue
What is the anatomy of the Taste Bud?
Taste buds include the taste receptor cells (TRCs) and Basal or Supporting cells.
What does the opening to the taste bud (taste pore) allow?
Allows chemical cues to enter the bud and come in contact w/ receptors located on the microvilli of taste cells.
Are Taste Receptor Cells (TRCs) neurons? Explain
NO, instead they synapse onto AFFERENT nerve endings of CN 7, 9 and 10
What is Gustation Transduction?
Different taste qualities are traduced by different molecular mechanisms
Where do cranial nerve AFFERENTS terminate into?
In the Nucleus of the Solitary Tract (NST) or Solitary Nucleus located in the brainstem .
What does the rostral 1/2 of the NST contain?
The gustatory nuclei
What does the Output from the NST travel to ?
The ventroposterior medial nucleus (VMN) of the Thalamus
***Which is responsible for communicating w/ the insula (insular cortex)
What is the insular cortex?
Is a portion of cerebral cortex that is folded deep within the lateral sulcus ( The fissure separating the temporal lobe from the parietal & frontal lobes)
What are the Medical conditions & exposures that alter taste perception?
1) Alzheimers
2) Acoustic neuromas
3) Bell’s palsy
4) Brain tumors
5) Chemotherapy/Radiation therapy
6) Cirrhosis
7) Depression
8) Diabetes
9) Middle Ear surgery
9) Psychiatric disorders
10) Renal failure
11) 3rd molar extractions
What did a prospective cohort study show regarding 3rd molar extractions?
Lower 3rd molar removal may cause light lingual sensibility impairment. Most remain undetected by patents
***Present 1 wk after the extraction & recover one month after surgery. (Taste buds are unaffected after these procedures)
What does the lingual nerve supply?
Supplies the mandibular division of the trigeminal nerve which supplies SENSORY info to the tongue.
-It also carries fibers from the facial nerve, which return taste information from the anterior 2/3 of the tongue.
What are common medication that alter taste perception?
1) Anticoagulants
2) Anti epileptic drugs
3) Antihistamines
4) Anti-hypertensive drugs
5) Antiseptics
6) Anti-ulcerative agents
7) Antivirals
8) Bronchodilators and Vasodilators
9) Diuretics
10) Hypnotics
11) Sympathomimetic drugs
