Physiology of taste and smell

Question 1

What do taste buds consist of?

Answer 1

Support cells and receptor cells arranged alternately

Question 2

Where are taste buds mainly located?

Answer 2

Papillae on the dorsum of the tongue

Question 3

What are the four types of papillae, and which of these contains no taste buds?

Answer 3

Fungiform, vallate, foliate, filliform*****

Question 4

How do APs in afferent gustatory axons from a) the anterior 2/3rds of the tongue b) the posterior 1/3rd of the tongue and c) the rest of the taste buds, reach the brainstem?

Answer 4

a) chorda tympani branch of facial nerve (CN VII)
b) glossopharyngeal nerve (CN IX)
c) vagus nerve (CN X)

Question 5

What are the five main tastes which can be perceived, and their respective chemical tastants?

Answer 5

1. Salty (NaCl and others)
2. Sweet (configurations of glucose)
3. Bitter (diverse group of chemicals including alkaloids)
4. Sour (acids with free H+)
5. Umami (amino acids, e.g. glutamate)

Question 6

Name the three categories of taste abnormality.

Answer 6

Ageusia, hypogeusia, dysgeusia

Question 7

Where is the olfactory mucosa located?

Answer 7

Ceiling/roof of nasal cavity

Question 8

How do odorants illicit an afferent olfactory signal?

Answer 8

Bind to cilia on olfactory rods of sensory cells; illicit depolarisation

Question 9

Which structure of which bone do olfactory nerve afferents pierce?

Answer 9

Cribriform plate of the ethmoid bone

Question 10

What properties must a substance have in order to be an odorant?

Answer 10

Sufficiently volatile and sufficiently water-soluble