Physiology of Taste and Smell

Question 1

What are the organs of gustation?

Answer 1

taste buds

Question 2

What is the life span of taste receptor cells?

Answer 2

10 days

Question 3

What replces taste receptor cells?

Answer 3

basal cells within the taste buds

Question 4

Where are taste buds present?

Answer 4

tongue; palate; epiglottis and pharynx

Question 5

What do taste buds consist of?

Answer 5

sensory receptor cells nad support cells arranged like slices of orange

Question 6

Where do the majority of taste buds sit?

Answer 6

in papillae in the tongue

Question 7

What are papillae?

Answer 7

finger-like structures which give rise to the rough appearance of the dorsum of the tonguee

Question 8

What are the 4 types of papillae?

Answer 8

filiform; fungiform; (circum)vallate; foliate

Question 9

Which of the papillae do not contain taste buds?

Answer 9

filliform

Question 10

How does the biding of tastant produce a receptor potential?

Answer 10

binding to receptor cells alters cell ionic channels and produces depolarising receptor potential

Question 11

What does the receptor potential initiate?

Answer 11

APs in afferent nerve fibres which synapse with receptor cells

Question 12

How do APs from the afferent nerve fibres reach the cortical gustatory areas?

Answer 12

signals are conveyed by cranial nerves via brainstem and thalamus

Question 13

What CN carries APs from the anterior 2/3rds of the tongue?

Answer 13

facial (chorda tympani)

Question 14

What CN carries APs from the posterior 1/3rd of the tongue?

Answer 14

glossopharyngeal

Question 15

What CN carries APs from taste buds not on the tongue eg epiglottis and pharynx?

Answer 15

vagus

Question 16

What are the 5 primary tastes?

Answer 16

salty; sour; sweet; bitter; unami

Question 17

What is a salty taste stimulated by?

Answer 17

chemical salts esp NaCl

Question 18

What is sour taste stimulated by?

Answer 18

acids which contain free H+ ions

Question 19

What is sweet taste stimualted by?

Answer 19

configuations of glucose

Question 20

What is bitter taste stimulated by?

Answer 20

diverse group of tastants inclding alkaloids; poisonous substances and toxic plant derivatives

Question 21

What is umami taste stimualted by?

Answer 21

umami= meaty/savoury

amino acids esp glutamate

Question 22

What ageusia

Answer 22

loss of taste

Question 23

what is hypogeusia?

Answer 23

reduces taste function

Question 24

What is dysgeusia?

Answer 24

distortion of taste function

Question 25

What can cause ageusia?

Answer 25

nerve damage; local inflammation; some nedocrine disorders

Question 26

What can cause hypogeusia?

Answer 26

chemo; medications

Question 27

What can cause dysgeusia?

Answer 27

glossitis; gum infections; tooth decay; reflux; uRTIs; medications; neoplasms; chemo; zinc deficiency

Question 28

What 3 cell types does olfactory mucosa contain?

Answer 28

olfactory receptor cells; supporting cells and basal cells

Question 29

What are olfactor receptors?

Answer 29

specialised endings of renewable afferent neurons

Question 30

How is a sense of smell created?

Answer 30

odorants beind to the cilia which are projected onto the surface of the olfactory mucosa. The cilia are part of the olfactory rod on the olfacor neuron

Question 31

What is life span of an olfactory receptor?

Answer 31

2 months

Question 32

How do the olfactory receptors reach the brain?

Answer 32

pierce the cribiform plate of the ethmoid bone and enter the olfactory bulbs in the inferior surface of hte brain which transmit along the olfactory tract to reach temproal lobe and olfactory areas

Question 33

How do odorants reach the olfactory receptors during quiet breathing?

Answer 33

by diffusion as olfactory mucosa is above normal path of airflow

Question 34

How does sniffing enhance sense of smel?

Answer 34

draws air currents upwards and creates turbulence to reac hthe olfactory mucosa

Question 35

What 2 features must a substance possess to be smelled?

Answer 35

must be sufficiently volatile; sufficiently water soluble- to dissolve in the mucus

Question 36

How can we differentiate between different odours?

Answer 36

receptors have different sensitivity to different substances

Question 37

What is anosmia?

Answer 37

inability to smell

Question 38

What are the causes of anosmia?

Answer 38

viral infection; allergy; nasal polyp; head injury

Question 39

What is hyposmia?

Answer 39

reduced ability to smell

Question 40

What is hyposmia an early sign of?

Answer 40

Parkinson's

Question 41

What is dysosmia?

Answer 41

altered sense of smell