Chemical Special SensesTaste
• Detection of environmental chemicals
• Biologically most important function to perceive danger (toxic/spoiled food, fire etc.)
• Both are required to perceive flavour
• But separate and distinct systems with parallel processing pathways which only merge at a high level in the cortex
• Strong and direct connections with basic needs and instincts (thirst, hunger, emotion, sex, memory)
GUSTATION:
• Requires a voluntary action of putting the food in our mouth (an action guided by our senses of vision and
olfaction)
• Tastants (the molecules that we taste) must be soluble in water (saliva)
OLFACTION:
• No voluntary action involved
• Odorants (the molecules that we smell) must have a high vapour pressure (e.g. Tendency to evaporate from
liquid to gas) so that we can inhale them
• Avoiding potentially harmful foodstuffs
i. Bitterness (plant alkaloids)
ii. High salt content or acidity
• Selecting foodstuffs which have a high energy content
i. Sugar
ii. Fat
iii. Alcohol
• Gustation is always the result of the active process of placing the foodstuff in the mouth, following
guidance by other senses
• Specialised organ = taste buds (primarily on tongue)
• Combinations of basic tastes
• Smell
• Texture
• Temperature
• Pain (spicy food)
• The nocirecptor proteins detecting extreme heat and extreme coldness are also responsible for detecting capsaicin (as
in chilli pepper) and menthol, respectively
• Both receptor proteins are expressed widely throughout the body (thus, we can feel the heat of pepper and the
coldness of menthol both inside and outside of our mouth)
Integration of Physiological Systems Page 1
• Detection of environmental chemicals
• Biologically most important function to perceive danger (toxic/spoiled food, fire etc.)
• Both are required to perceive flavour
• But separate and distinct systems with parallel processing pathways which only merge at a high level in the cortex
• Strong and direct connections with basic needs and instincts (thirst, hunger, emotion, sex, memory)
GUSTATION:
• Requires a voluntary action of putting the food in our mouth (an action guided by our senses of vision and
olfaction)
• Tastants (the molecules that we taste) must be soluble in water (saliva)
OLFACTION:
• No voluntary action involved
• Odorants (the molecules that we smell) must have a high vapour pressure (e.g. Tendency to evaporate from
liquid to gas) so that we can inhale them
• Avoiding potentially harmful foodstuffs
i. Bitterness (plant alkaloids)
ii. High salt content or acidity
• Selecting foodstuffs which have a high energy content
i. Sugar
ii. Fat
iii. Alcohol
• Gustation is always the result of the active process of placing the foodstuff in the mouth, following
guidance by other senses
• Specialised organ = taste buds (primarily on tongue)
• Combinations of basic tastes
• Smell
• Texture
• Temperature
• Pain (spicy food)
• The nocirecptor proteins detecting extreme heat and extreme coldness are also responsible for detecting capsaicin (as
in chilli pepper) and menthol, respectively
• Both receptor proteins are expressed widely throughout the body (thus, we can feel the heat of pepper and the
coldness of menthol both inside and outside of our mouth)
Integration of Physiological Systems Page 1
