1 D: Gustation

Question 1

What have studies shown regarding our taste buds?

Answer 1

We can distinguish between 4000-10,000 diff chemicals and 4-5 primary taste qualities.

Question 2

What are the 4-5 taste qualities?

Answer 2

1) Salty (NacL)
2) Sweet (Sucrose)
3) Sour ( HCL or citric acid)
4) Bitter ( Quinine hydrochloride QHCL)
5) Umami ( glutamate; MSG)

Question 3

What is a taste bud?

Answer 3

Taste receptor cells “Taste cells” located within clusters of cells known as TASTE BUDS

Question 4

Where are taste buds found?

Answer 4

Upon the papillae located over the 1) Tongue 2) palate

3) pharynx 4) epiglottis

Question 5

What are Fungiform Papillae like?

Answer 5

• Mushroom-like

- Scattered over ENTIRE TONGUE SURFACE, but most abundant at the TIP & along its ANTERIOR SIDES

Question 6

What do Fungiform Papillae respond to?

Answer 6

**Sweet & **salty substances but also sour.

Question 7

What are Foliate (edges) Papillae like?

Answer 7

• Folded structures

- Most abundant on the MIDDLE edges of the tongue

Question 8

What do Foliate Papillae respond to?

Answer 8

MAINLY SOUR

Question 9

What taste buds are innervated by the chorda tympani brach of CN 7 ( anterior 2/3 of the tongue) ?

Answer 9

**Fungiform papillae & some of the Foliate papillae

Question 10

What are Circumvallate Papillae like?

Answer 10

• LARGEST and LEAST NUMEROUS

- Form an inverted V shape at the back of tongue

Question 11

What do Circumvallate Papillae respond to?

Answer 11

BITTER substances

Question 12

What taste buds are innervated by the glossopharyngeal CN 9 ( posterior 1/3 of the tongue) ?

Answer 12

***Taste buds on the CIRCUMVALLATE and some Foliate papillae

Question 13

What are the taste buds in the region of the epiglottis supplied by?

Answer 13

CN 10 ( vagus)

Question 14

What are the taste buds in the region of the palate are supplied by?

Answer 14

CN 7 ( Facial)

Question 15

What is the myth of Taste Buds?

Answer 15

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

Question 16

What is the anatomy of the Taste Bud?

Answer 16

Taste buds include the taste receptor cells (TRCs) and Basal or Supporting cells.

Question 17

What does the opening to the taste bud (taste pore) allow?

Answer 17

Allows chemical cues to enter the bud and come in contact w/ receptors located on the microvilli of taste cells.

Question 18

Are Taste Receptor Cells (TRCs) neurons? Explain

Answer 18

NO, instead they synapse onto AFFERENT nerve endings of CN 7, 9 and 10

Question 19

What is Gustation Transduction?

Answer 19

Different taste qualities are traduced by different molecular mechanisms

Question 20

Where do cranial nerve AFFERENTS terminate into?

Answer 20

In the Nucleus of the Solitary Tract (NST) or Solitary Nucleus located in the brainstem .

Question 21

What does the rostral 1/2 of the NST contain?

Answer 21

The gustatory nuclei

Question 22

What does the Output from the NST travel to ?

Answer 22

The ventroposterior medial nucleus (VMN) of the Thalamus

***Which is responsible for communicating w/ the insula (insular cortex)

Question 23

What is the insular cortex?

Answer 23

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)

Question 24

What are the Medical conditions & exposures that alter taste perception?

Answer 24

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

Question 25

What did a prospective cohort study show regarding 3rd molar extractions?

Answer 25

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)

Question 26

What does the lingual nerve supply?

Answer 26

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.

Question 27

What are common medication that alter taste perception?

Answer 27

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