Hearing, Smell, Taste- Taste

Question 1

What are the 5 tastants?

Answer 1

• salty
• sour
• sweet
• bitter
• umami
• each has its own receptor, so 5 taste receptors

Question 2

What are clusters of taste receptor cells?

Answer 2

• taste buds
• clusters of 50-150 taste receptor cells

Question 3

Where are taste buds located?

Answer 3

• located on sides of taste pores between papillae (bumps)

Question 4

Papillae are specialized for specific tastants: T/F

Answer 4

false- they are not specialized for specific tasants

Question 5

Where are circumvallate papillae located?

Answer 5

back of tung

Question 6

where are foliate papillae located?

Answer 6

along the sides of the tongue

Question 7

Where are fungiform papillae located?

Answer 7

in the front of the tongue

Question 8

Are taste cells neurons?

Answer 8

• no
• do not have action potentials

Question 9

How often are taste cells replaced?

Answer 9

every 10-14 days

Question 10

Taste transduction

Answer 10

• 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

Question 11

Salty

Answer 11

Na+ ions flow through open ion channels in the taste cell membrane, causing depolarization

Question 12

Sour

Answer 12

• 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

Question 13

Sweet

Answer 13

• 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

Question 14

umami

Answer 14

• 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

Question 15

Bitter

Answer 15

• 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

Question 16

How many types of bitter receptors?

Answer 16

around 30 types of T2R receptors, so we can percieve many bitter flavors

Question 17

Which cranial nerve is a part of taste transduction?

Answer 17

glassopharyngeal cranial nerve