Physiology: taste Flashcards
SPACED
What is the signal?
What is the peripheral receptor?
Tastants
Taste cells
SIGNAL
What substance helps the tastants get to taste cell?
Saliva
SIGNAL
- How does saliva help tastants get to the taste cells?
- What part of the taste cells will tastants ultimately bind to?
Solubilisation of tastants: tastants can interact with receptors
Diffusion of tastats: spreads tastants over the tongue
Receptor proteins on their apical surface/microvilli
PERIPHERAL RECEPTORS
Name the subcomponents of the tongue
Tongue –> papillae –> taste buds –> taste cells
PERIPHERAL RECEPTORS: PAPILLAE
Differentiate filiform and fungiform papillae
Memory trick?
Fungiform are larger, like mushrooms (fungi)
Filiform fill in the rest of the space
PERIPHERAL RECEPTORS: PAPILLAE
Differentiate circumvallate (vallate) and folate papillae
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?
50-150
Taste buds have a basal cell population (stem cells - replace them)
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?
Epithelial
It goes through an opening in the taste bud called the taste pore
Microvilli, receptor proteins
Afferent neurons (via synapses)
ATP, serotonin
3
PERIPHERAL RECEPTORS: TASTE CELLS
Type I glial like cells
- What taste type do they detect?
- What receptor type (for tastants) do they have?
Salty
Na+ channel
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?
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
PERIPHERAL RECEPTORS: TASTE CELLS
Type III presynaptic cells
- What taste does it detect?
- What receptor type does it have?
Sour
Ion channel (Na+ and H+ influx)
PERIPHERAL RECEPTORS: TASTE CELLS
Type III presynaptic cells
- What 2 signals can they depolarise in response to?
Sour tastants themselves
ATP released by type II cells binding to P2Y receptors
PERIPHERAL RECEPTORS: TASTE CELLS
Type III presynaptic cells
- What is the main NT it releases?
- What other NTs does it release?
Serotonin
NPY and CCK (satiety signals), ATP
PERIPHERAL RECEPTORS: TASTE CELLS
Signal transduction
- Describe signal transduction in type II cells
PERIPHERAL RECEPTORS: TASTE CELLS
Signal transduction
- Describe signal transduction in type III cells
Binding of sour tastant
Depolarisation leads to intracellular calcium release/AP generation –> exocytosis of 5-HT (serotonin) –> stimulation of afferent sensory neuron