Physiology of Taste and Smell Flashcards Preview

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Flashcards in Physiology of Taste and Smell Deck (44)
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1
Q

what type of receptors are involved in taste and smell and what are they stimulated by?

A

chemoreceptors, stimulated by binding to particular chemicals

2
Q

what other type of receptors influence taste perception?

A

smell receptors

3
Q

where are most sensory receptor cells found?

A

in taste buds

4
Q

what do taste buds consist of and how are they arranged?

A

sensory receptor cells and support cells, arranged like slices of oranges

5
Q

what is the life span of taste receptor cells?

A

about 10 days

6
Q

what replaces taste receptor cells?

A

basal cells within the taste buds

7
Q

what do taste receptor cells within taste buds synapse with?

A

afferent nerve fibres

8
Q

how many types of papillae are there in the tongue?

A

4

9
Q

what are the 4 types of papillae in the tongue?

A

filliform, fungiform, vallate and foliate

10
Q

what type of papillae do not contain taste buds?

A

filliform

11
Q

what does binding of taste provoking chemicals to receptor cells cause?

A

altered cell ionic channels and produces depolarisation receptor potential

12
Q

what does receptor potential initiate?

A

action potentials in afferent nerve fibres which synapse with receptor cells

13
Q

which areas of the brain are signals from receptor cells conveyed to?

A

cortical gustory areas

14
Q

afferent nerve fibres from the anterior 2/3rd of tongue reaches the brainstem via what nerve?

A

chorda tympani branch of facial nerve

15
Q

afferent nerve fibres from posterior 1/3rd of tongue reaches the brainstem via what nerve?

A

glossopharyngeal nerve

16
Q

what stimulates the salty taste?

A

chemical salts esp NaCl

17
Q

what stimulates the sour taste?

A

acids which contain free hydrogen ions

18
Q

what stimulates the sweet taste?

A

by configuration of glucose

19
Q

what stimulates the bitter taste?

A

by diverse groups of tastants, including alkaloids, poisons, toxic plant derivatives

20
Q

what triggers the umami taste?

A

amino acids esp glutamate

21
Q

what is ageusia?

A

loss of taste function

22
Q

what can ageusia be caused by?

A

nerve damage, local inflammation, some endocrine disorders

23
Q

what is hypogeusia?

A

reduced taste function

24
Q

what can hypogeusia?

A

chemotherapy and some medications

25
Q

what is dysgeusia?

A

distortion of taste function

26
Q

what can cause dysgeusia?

A

glossitis, gum infections, tooth decay, URI, infections, medications etc

27
Q

what are the 3 types of cells in olfactory mucosa?

A

olfactory receptor cells, supporting cells and basal cells

28
Q

what are the olfactory receptors?

A

specialised endings of renewable afferent neurons

29
Q

what does each neuron in the olfactory receptors consist of?

A

a thick short dendrite and an expanded end called an olfactory rod

30
Q

what are on the olfactory rods?

A

cilia which project to the surface of the olfactory mucosa

31
Q

what do odorants bind to?

A

cilia

32
Q

what is the life span of olfactory receptors?

A

about 2 months

33
Q

what cells act as precursors for new olfactory receptor cells?

A

basal cells

34
Q

what forms the afferent fibres of olfactory nerve?

A

axons of olfactory receptors

35
Q

what transmits smell information to the brain?

A

olfactory bulbs

36
Q

during quiet breathing, how do odorants reach the smell receptors?

A

by diffusion

37
Q

what enhances smelling and how?

A

the act of sniffing enhances smelling by drawing air currents upwards within the nasal cavity

38
Q

what must a substance be to be smelled?

A
  1. sufficiently volatile

2. sufficiently water soluble

39
Q

why must a substance be sufficiently water soluble to be smelled?

A

so it can dissolve in the mucous coating of olfactory mucosa

40
Q

what is anosmia?

A

inability to smell

41
Q

causes of anosmia?

A

viral infecions, allergy, nasal polyps, head injury

42
Q

what is hyposmia?

A

reduced ability to smell

43
Q

what can hyposmia be an early sign of?

A

Parkinson’s disease

44
Q

what is dysomia?

A

altered sense of smell