Gustation*

Question 1

Chemoreception and taste - sending info? GI secretion?

Answer 1

Taste information is sent to the old areas of the brain associated with memory and emotion
Taste can regulate GI secretions

Question 2

Central pathways for gustations - from tongue to brain? from brain to GI?

Answer 2

Pass through the thalamus before they are projected to their relevant cortical areas
Taste afferents from the midbrain are involved in the visceral reflexes (secrete gastric juices)

Question 3

What information does gustation give?

Answer 3

Quality and quantity of food
General sensation
Flavour
Whether food should be swallowed
Chemosensory and somatosensory info

Question 4

Gustation and taste buds - different types and signal transduction, Umami and nucleotides?

Answer 4

Segregated into 4 groups
Saltiness (Na ions)
Sourness (H+ ions)
Sweetness (GPCR)
Bitterness  (GPCR)
Umami - associated with glutamate and other nucleotides

Question 5

Sensory innervation the the oral cavity - back tongue, front tongue, soft palate and mouth?

Answer 5

Facial - front tongue
Glossopharyngeal - back tongue
Vagus - soft palate and mouth

Question 6

Different types of taste buds?

Answer 6

Circumvallate
Foliate
Fungiform

Question 7

Taste receptors - different types of receptors and receptor families?

Answer 7

T1R sense sweet
T2R sense bitter
t-mGluR4 senses glutamate and is the umami
MDEG/ENaC sense sourness and saltiness
T1R/T2R and t-mGluR4 are GPCRs

Question 8

What allows different people to taste 2 different tastes for the same substance?

Answer 8

High amount of variable aas, that are exchangeable and so enable the variance in taste perception

Question 9

Dimerisation allows taste receptors to work- which dimers for which taste sense?

Answer 9

Sweet - T1R3 and TIR2
AAs - T1R3 and T1R1
Some taste buds have a variable range of receptors

Question 10

Taste transduction for each taste?

Answer 10

Bitter and sweet ligands use GPCRs
Bitter - ligand binds, act transducin, releases Ca from intra store, causes depol and exocytosis of NuT and sense response the the neurons
Sweet - ligand binds, act gustducin, act cAMP, closes K+ chs and depolarises cells, exocytosis of NuT and sense response the the neurons
Sour and Salt - alter ion chs and depolarise cell triggering extra Ca entry, exocytosis of NuT and sense response the the neurons