L2 Taste and Smell

Question 1

What are the characteristics of taste and smell ?

Answer 1

Referred to as the chemical senses
Mediated by receptors that are called chemoreceptors
Taste - chemicals dissolve in our mouth
Smell - gaseous chemicals are inhaled into the nasal passage
They are closely linked

Question 2

What are the taste buds ?

Answer 2

Foliate - at the very back, sides of the tongue
Circumvallate - back of the tongue, surrounded by moats of saliva
Fungiform - all over the tongue
Filoform - no taste, breaks down food

Question 3

What are the 3 sets of afferent nerve fibres ?

Answer 3

Chorda tympani - front part of the tongue
Glossopharyngeal - back region of the tongue
Vagus - throat, pharynx, larynx
They each take information to the nervous system

Question 4

How is taste quality encoded ?

Answer 4

Every cell will respond to all of the 4 main tastes but some will be more sensitive to others

Question 5

What are the limits of human taste sensitivity ?

Answer 5

We are the most sensitive to bitter tastes as they are generally the most poisonous
The front of the tongue senses sweetness and bitterness, the back and sides is saltiness and sourness

Question 6

What is the neural and psychological response to taste ?

Answer 6

Electrophysiological recording from taste fibres during surgery
Patient made intensity estimates and the neural response matched his answers

Question 7

What are non-tasters, tasters and super-tasters ?

Answer 7

50% of the population are tasters, 25% find taste undetectable, 25% find taste extremely strong
This is a genetic trait

Question 8

What are the receptors that mediate smell perception ?

Answer 8

Molecules enter the nasal cavity
The olfactory binding protein in the nose mucus carries the odorant to the olfactory cell
10 million olfactory receptors

Question 9

What are the neural pathways for smell perception ?

Answer 9

Evidence supports the lock and key hypothesis (Amoore, 1970)
Specific proteins pick up odorants
Olfactory receptor cells send axons through holes in a bone in the nasal cavity, to the olfactory, to the olfactory bulb in the brain

Question 10

How is odour quality encoded ?

Answer 10

Olfactory nerve fibres respond to different odours with different sensitivities
Cross-fibre patterns of activity
Coded in the specific pattern of activity within an ensemble of group neurons

Question 11

What are the limits of human smell sensitivity ?

Answer 11

Detection threshold depends on - substance, purity, delivery
The olfactory system is remarkably sensitive (can smell 1 part per 50 billion parts of gas)
Females are more sensitive than males

Question 12

What is anosmia ?

Answer 12

Odour blindness

Question 13

Does smell interact with taste ?

Answer 13

Yes
Research found that without smell, the ability to identify food taste alone was poor
Smell greatly influences the taste