Physiology: taste Flashcards

1
Q

SPACED
What is the signal?
What is the peripheral receptor?

A

Tastants
Taste cells

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2
Q

SIGNAL
What substance helps the tastants get to taste cell?

A

Saliva

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3
Q

SIGNAL
- How does saliva help tastants get to the taste cells?
- What part of the taste cells will tastants ultimately bind to?

A

Solubilisation of tastants: tastants can interact with receptors
Diffusion of tastats: spreads tastants over the tongue

Receptor proteins on their apical surface/microvilli

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4
Q

PERIPHERAL RECEPTORS
Name the subcomponents of the tongue

A

Tongue –> papillae –> taste buds –> taste cells

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5
Q

PERIPHERAL RECEPTORS: PAPILLAE
Differentiate filiform and fungiform papillae
Memory trick?

A

Fungiform are larger, like mushrooms (fungi)
Filiform fill in the rest of the space

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6
Q

PERIPHERAL RECEPTORS: PAPILLAE
Differentiate circumvallate (vallate) and folate papillae

A
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7
Q

PERIPHERAL RECEPTORS: TASTE BUDS
- How many taste cells per taste bud?
- Taste cells need to be frequently replaced, as they’re epithelial and exposed to toxins. How is this done?

A

50-150
Taste buds have a basal cell population (stem cells - replace them)

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8
Q

PERIPHERAL RECEPTORS: TASTE CELLS
What cell type is it?

Taste cells have an apical and basal pole.

At the apical pole:
- How does it reach the surface of the tongue?
- What cytoskeletal structure does the apical pole have?
- What signal transduction molecules are found on these cytoskeletal structures?

At the basal pole:
- What does it communicate with?

What is the main signalling molecule and NT? Secondary?

How many major classes of taste cells are there?

A

Epithelial

It goes through an opening in the taste bud called the taste pore
Microvilli, receptor proteins

Afferent neurons (via synapses)

ATP, serotonin

3

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9
Q

PERIPHERAL RECEPTORS: TASTE CELLS
Type I glial like cells
- What taste type do they detect?
- What receptor type (for tastants) do they have?

A

Salty
Na+ channel

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10
Q

PERIPHERAL RECEPTORS: TASTE CELLS
Type II receptor cells
- What taste types do they detect?
- What receptor type (for tastants) do they have?
- What other major membrane channels does it have? What is its role?

A

Bitter, umami, sweet
GPCR’s (different combinations for the above tastes)
Panexxins: form membrane channels that allow ATP to be secreted into the extracellular space

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11
Q

PERIPHERAL RECEPTORS: TASTE CELLS
Type III presynaptic cells
- What taste does it detect?
- What receptor type does it have?

A

Sour
Ion channel (Na+ and H+ influx)

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12
Q

PERIPHERAL RECEPTORS: TASTE CELLS
Type III presynaptic cells
- What 2 signals can they depolarise in response to?

A

Sour tastants themselves
ATP released by type II cells binding to P2Y receptors

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13
Q

PERIPHERAL RECEPTORS: TASTE CELLS
Type III presynaptic cells
- What is the main NT it releases?
- What other NTs does it release?

A

Serotonin
NPY and CCK (satiety signals), ATP

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14
Q

PERIPHERAL RECEPTORS: TASTE CELLS
Signal transduction
- Describe signal transduction in type II cells

A
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15
Q

PERIPHERAL RECEPTORS: TASTE CELLS
Signal transduction
- Describe signal transduction in type III cells

A

Binding of sour tastant

Depolarisation leads to intracellular calcium release/AP generation –> exocytosis of 5-HT (serotonin) –> stimulation of afferent sensory neuron

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16
Q

AFFERENT PATHWAYS
How many order neurons are there?

A

3

17
Q

AFFERENT PATHWAYS
First order neurons
- Where are their dendrites located?
- What cranial nerves form their axons
- Where do they synapse?

A

Superior tongue, inferior tongue, pharynx
Cranial nerve 7 (facial), 9 (glossopharyngeal), 10 (vagus)
NTS of the medulla

18
Q

AFFERENT PATHWAYS
Second order neurons
- Where are their somas located?
- Where do they project to?

A

Somas in the NTS of the medulla

Project to the ventral posterior medial nucleus of the thalamus

19
Q

AFFERENT PATHWAYS + CENTRAL PROCESSING
Third order neurons
- Where are their somas located?
- Where do they project to? (This is also their site of central processing)

A

Soma in the ventral posterior medial nucleus of the thalamus

Project to the gustatory cortex (anterior insula)

20
Q

AFFERENT PATHWAYS + CENTRAL PROCESSING
Label the following

A
21
Q

DISRUPTION
Names for:
- Inability to taste?
- Decreased taste?
- Distorted taste?

Can taste disruption have a strong impact on QoL (eg. depression and anxiety)?

Can disrupted taste be life threatening?

A

Ageusia, hypogeusia, dysgeusia
Yes
Yes - esp if can’t detect toxic tastes