Physiology of Taste and Smell Flashcards

1
Q

What type of receptors are responsible for taste and smell?

A

chemoreceptors

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2
Q

Taste perception can be influenced by smell receptors. TRUE/FALSE?

A

TRUE

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3
Q

What are the two main types of cell found in the taste buds?

A

sensory receptor cells

and support cells

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4
Q

What cells regenerate the receptor cells, and after how long?

A

replaced from basal cells

after about 10 days (lifespan)

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5
Q

What type of nerve fibres are present behind the taste buds to rely information to the brain?

A

afferent nerve fibres

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6
Q

Where are taste buds mainly present?

A

tongue
palate
epiglottis
pharynx

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7
Q

Where are taste buds found in the tongue?

A

In papillae

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8
Q

What are the four types of papillae found on the tongue?

A

Filliform
Fungiform
Vallate
Foliate

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9
Q

What type of papillae do NOT contain taste buds?

A

Filliform

mostly found at tip of tongue - are sensitive to touch and temp

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10
Q

How do APs arise in the afferent nerve fibres behind the taste buds?

A

Tastants bind to receptor cells
Depolarise membrane
Fire AP

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11
Q

Where are taste signals processed in the brain?

A

cortical gustatory areas

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12
Q

What cranial nerves are involved in afferent signals of taste reaching the brainstem?

A

CN VII - chorda tympani = anterior 2/3 of the tongue

CN IX = posterior 1/3 of the tongue

CN X = areas other than tongue, e.g. epiglottis and pharynx

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13
Q

What are the 5 primary tastes?

A
Salty
Sour
Sweet
Bitter
Umami (meaty or savory)
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14
Q

What chemical compound provokes a salty taste?

A

NaCl

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15
Q

What chemical provokes a sweet taste?

A

Glucose or a configuration of glucose

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16
Q

What ion is responsible for sour tasting food?

A

H+

17
Q

What substances cause a bitter taste in the mouth?

A

diverse group of tastants:

  • alkaloids
  • poisonous substances
  • toxic plant derivatives
18
Q

Umami taste is provoked by what chemical compound?

A

amino acids especially glutamate

19
Q

What is the difference between Ageusia, Hypogeusia and Dysgeusia?

A

Ageusia (loss of taste function)
Hypogeusia (reduced taste function)
Dysgeusia (distortion of taste function

20
Q

What can cause ageusia?

A
  • nerve damage
  • local inflammation (e.g. glossitis, radiation, tobacco)
  • some endocrine disorders
21
Q

What can cause hypogeusia?

A

chemotherapy

medications

22
Q

What can cause dysgeusia?

A
glossitis
gum infections/tooth decay
reflux
URTI
medications/chemotherapy
neoplasms
zinc deficiency
23
Q

What are the 3 cell types found in the olfactory mucosa?

A

olfactory receptor cells
supporting cells
basal cells

24
Q

What are olfactory receptors?

A

specialised endings of renewable afferent neurons

25
Q

How do the neurons of olfactory receptors appear?

A

thick short dendrite and an expanded end called an olfactory rod

26
Q

What part of the olfactory nerve pierces the cribriform plate of the ethmoid bone to enter the olfactory bulbs in the brain?

A

Axons of olfactory receptors collectively form afferent fibres of olfactory nerve which pierce the ethmoid bone

27
Q

After reaching the olfactory bulb, where are signals transmitted to perceive a smell?

A

neurons passes along the olfactory tract to reach temporal lobe and olfactory areas

28
Q

Why is quiet breathing less efficient for perceiving smells?

A

olfactory mucosa is above the normal path of airflow

=> During quiet breathing odorants only reach smell receptors by diffusion

29
Q

What are the 2 factors which enhance the ability to smell a substance?

A

Substance is sufficiently volatile
It is sufficiently water soluble
=> i.e. can dissolve in the mucus coating of olfactory mucosa

30
Q

WHat is the difference between anosmia, hyposmia and dysosmia?

A

Anosmia (inability to smell):
Hyposmia (reduced ability to smell):
Dysosmia (altered sense of smell)

31
Q

WHat causes anosmia and hyposmia?

A

viral infections
allergy
nasal polyps
head injury

Hyposmia may be early sign of Parkinson’s disease

32
Q

What is caused in dysosmia?

A

differently interpreting some odours

hallucinations of smell