Hearing, Smell, Taste- Taste Flashcards
What are the 5 tastants?
- salty
- sour
- sweet
- bitter
- umami
- each has its own receptor, so 5 taste receptors
What are clusters of taste receptor cells?
- taste buds
- clusters of 50-150 taste receptor cells
Where are taste buds located?
- located on sides of taste pores between papillae (bumps)
Papillae are specialized for specific tastants: T/F
false- they are not specialized for specific tasants
Where are circumvallate papillae located?
back of tung
where are foliate papillae located?
along the sides of the tongue
Where are fungiform papillae located?
in the front of the tongue
Are taste cells neurons?
- no
- do not have action potentials
How often are taste cells replaced?
every 10-14 days
Taste transduction
- receptors o cillia are bound by tastants
- receptor activation produces receptor potentials (like EPSPs)
- Instead of an action potential, receptor potential releases neurotransmitter onto Glassopharyngeal cranial nerve
- Thalamus, then cortex
- there is a gustatopic map in cortex
Salty
Na+ ions flow through open ion channels in the taste cell membrane, causing depolarization
Sour
- we perceive acidic solutions as sour (acid=high concentration of H+)
- Acid sensitive K+ ion channels are blocked, preventing K+ leaving the cell and leading to depolarization
Sweet
- Sugars bind to TIR2 and TIR3 receptors, causing them to join (dimerize)
- Tastant binding to receptor -> activation of G-protein ->second messengers->Ca+2 flow into cell ->receptor potential -> NT release
umami
- amino acid receptor (mostly activated by L-glutamate and monosodium glutamate)
- g-protein coupled metabotropic-like receptor; heterodimer of TIR1 and TIR3
- Tastant binding to receptor->activation of G-protein->second messengers->Ca+2 flow into cell -> receptor potential ->NT release
Bitter
- T2R receptors: G-protein coupled metabotropic-like receptors
- Tastant binding to receptor->activation of G-protein->second messengers->Ca2+ flow into cell ->receptor potential-> NT release
How many types of bitter receptors?
around 30 types of T2R receptors, so we can percieve many bitter flavors
Which cranial nerve is a part of taste transduction?
glassopharyngeal cranial nerve