Physiology of Taste and Smell

Question 1

the receptors for taste and smell are what type of receptors?

Answer 1

chemoreceptors

Question 2

what is the role of sensory cells in taste and smell?

Answer 2

transduce chemical, electromagnetic and mechanical stimuli into action potentials

Question 3

what is the resulting action of taste and smell receptors

Answer 3

induces a pleasurable or objectionable sensation
provides a checkpoint for quality control
influences the flow of digestive juice

Question 4

what are the sense organs of taste?

Answer 4

taste buds

Question 5

what is the structure of taste buds?

Answer 5

sensory receptor cells and support cells arranged like slices of orange

Question 6

where are taste buds present?

Answer 6

tongue, palate, epiglottis, and pharynx

Question 7

where are the majority of taste buds located?

Answer 7

papillae of the tongue

Question 8

what are papillae?

Answer 8

are finger-like structures which gives rise to the rough appearance of the dorsum of the tongue

Question 9

what are the 4 types of papillae of the tongue?

Answer 9

 Filiform: most numerous – do not contain taste buds
 Fungiform
 Vallate
 Foliate

Question 10

what are the two types of cells found in the taste bud?

Answer 10

Gustatory

Basal

Question 11

what is the structure of gustatory cells?

Answer 11

 Project thread of membrane that runs down to a taste pore

 Synapse with afferent nerve fibres – separate axon until brain

Question 12

afferent taste fibres reach the brain via…

Answer 12

Cranial Nerves
o VIIth
o IXth
o Xth

Question 13

what are the 5 primary tastes?

Answer 13

salty, sour, sweet, bitter, umami

Question 14

how is salty taste stimulated?

Answer 14

stimulated by chemical salts especially sodium chloride (NaCl)

Question 15

how is sour taste stimulated?

Answer 15

stimulated by acids which contain free hydrogen ions (H+)

Question 16

how is sweet taste stimulated?

Answer 16

stimulated by configuration of glucose

Question 17

how is bitter taste stimulated?

Answer 17

stimulated by diverse group of tastants, including e.g. alkaloids, poisonous substances, and toxic plant derivatives

Question 18

how is umami taste stimulated?

Answer 18

triggered by amino acids especially glutamate

Question 19

what are the requirements for a substance to be smelled?

Answer 19

sufficiently volatile

sufficiently water soluble to disolve in olfactory mucosa

Question 20

what is the olfactory mucosa?

Answer 20

patch of mucosa in the ceiling (dorsal roof) of the nasal cavity

Question 21

what are the cells of the olfactory mucosa?

Answer 21

olfactory receptor cells, supporting cells and basal cells (

Question 22

what is the structure and pathway of olfactory receptors?

Answer 22

o Each neuron has a thick short dendrite and an expanded end called an olfactory rod
o From the olfactory rods, cilia project to the surface of the olfactory mucosa

Question 23

what is the summary process of smell?

Answer 23

1. Odorants land on epithelium, dissolve into mucus, and bind to receptors to olfactory sensory neurons
2. Axons of olfactory receptors collectively form afferent fibres of olfactory nerve
   • Converge with other cells at the glomerulus? then meets with the dendritic cells of mitral cells
   • These pierce the cribriform plate of the ethmoid bone and enter the olfactory bulbs in the inferior surface of the brain
3. From the olfactory bulb neurons passes along the olfactory tract to reach temporal lobe and olfactory areas