Specific Sensory Systems Special Senses – Taste (Gustation) and Smell (Olfacation)

Question 1

Gustation

What are Taste buds?

Answer 1

found on tongue and throat, small groups of cells (including taste receptor cells), sense organ for gustation

For taste sensations to occur, food must be dissolved in liquid (i.e., saliva

Question 2

What are the 5 main taste receptor types?

Answer 2

Salty
Sweet
Sour
Bitter
Umami

Question 3

Types of Tase Receptors and their Activation

Salty

Answer 3

Na+ from salty foods enters channels in the receptor cell membrane -> depolarization

Question 4

Types of Tase Receptors and their Activation

Sweet

Answer 4

Membrane proteins bind to sugars (i.e., glucose) and artificial sweeteners (i.e., aspartame)

• Downstream affects – K+ channels blocked

Question 5

Types of Tase Receptors and their Activation

Sour

Answer 5

H+ ions from acidic foods block K+ channels on receptor cells -> Loss of hyperpolarizing

K+ leak depolarizes the cel

Question 6

Types of Tase Receptors and their Activation

Bitter & Umami

Question 7

What is Olfaction?

Answer 7

Plays a major role in our perception of flavour

Question 8

What are Olfactory afferent neurons?

Answer 8

Olfactory afferent neurons found in the olfactory epithelium (upper part of nasal cavity)

• Single enlarged dendrite extends from the receptor neuron to the surface of the epithelium
• Cilia extend from the dendrite and are bathed in mucous – contain receptor proteins that bind to odour molecules

Question 9

What is the Pathway for Detection of Odours

Answer 9

Odourant  nasal cavity  protein receptor on cilia of
olfactory receptors afferent fibre depolarization  olfactory
nerve  olfactory bulbs (underside of frontal lobe)  olfactory
cortex (temporal lobe) and limbic system

*The only sensory system that does not synapse in the thalamus prior to reaching the cortex

Question 10

Variability in Odour Discrimination

Answer 10