Physiology of taste and smell

Question 1

receptors involved?

Answer 1

chemoreceptors

Question 2

what are the organs of taste?

• describe structure
• synapse with what?
• located?

Answer 2

• taste buds
• sensory receptor cells and support cells ranges in alternating pattern with microvilli on top
• afferent nerve fibres
• toungue, pharynx, palate and epiglottis

Question 3

name the 4 types of papillae

-ones that contain tastebuds?

Answer 3

fungiform, vallate, foliate (contain tastebuds)

filliform

Question 4

what does binding of a tasting to the receptor cell do?

-CN involved?

Answer 4

alters the cells ionic channels producing depolarising receptor potential
this initiates APs in afferent nerve fibres, the signal is conveyed via the brainstem and thalamus to the cortical gustatory areas

-CN7, CN 9, CN10

Question 5

define the following and give causes:

• Ageusia
• Hypogeusia
• dysgeusia

Answer 5

• loss of taste caused by nerve damage/local inflammation/ endocrine disorders
• reduced taste caused by chemo/medication
• distortion, many causes e.g. tooth decay

Question 6

mucosa involved in smell?

• location
• components

Answer 6

olfactory mucosa

• ceiling of the nasal cavity
• 3 cell types, olfactory receptor cells, supporting cells and basal cells (precursors for the new olfactory receptor cells)

Question 7

structure of an olfactory receptor?

Answer 7

sepcialised endings of renewable afferent neurons
thick short dendrite and expanded end (olfactory rod)
cilia project onto the olfactory mucosa surface
oderants can then bind to the cilia

Question 8

Axons of the olfactory receptors form what?

and go via what?

Answer 8

the olfactory nerve

pierce the cribriform plat of the ethmoid bone and enter the olfactory bulbs

Question 9

Define the following and give causes:

• Anosmia
• Hyposmia
• Dysosmia

Answer 9

• inability to smell, viral infection, allergy, polyps, head injury
• reduced sense of smell, ^^ or parkinsons
• altered sense of smell, smell hallucinations