Biological Olfaction - The Electronic Nose Artificial Olfaction Technology - page 66

Chapter 3
Biological Olfaction
3.1 Introduction
Olfaction is an often over-looked but vital sense to our everyday living. Olfactory
information can influence behavior, social interactions, and in many animals,
reproduction. Humans, who rely on smell less than many other mammals, can
distinguish between 5,000 and 10,000 different odorants. Olfaction has an extre-
mely high importance in the human being. It is one of the five main senses: Sight,
Smell, Taste, Hearing and Touch [ 1 ]. There are multiple occupations for which
olfaction is depended on for making an accessible. These include chefs, fire-
fighters, plumbers, wine merchants, perfumers, cosmetic retailers, and chemical
plant workers.
3.2 The Nose: How It Works
The human nose is in fact the main organ of taste as well as smell. The so-called
taste-buds on our tongues can only distinguish four qualities—sweet, sour, bitter
and salt -all other ''tastes'' are detected by the olfactory receptors high up in our
nasal passages.
Anything that has an odor constantly evaporates tiny quantities of molecules
that produce the smell, so-called odorants. A sensor that is capable to detect these
molecules is called a chemical sensor. In this way the human nose is a chemical
sensor and the smell is a chemical sense [ 2 ]. The nose is an important regulator of
social life. Pheromones are a class of long distance chemical messenger hormones
that regulate social relations, behavioral and physiological responses in insects and
many mammals.
The mammalian olfactory system regulates a wide range of multiple and
integrative functions such as physiological regulation, emotional responses (e.g.,
anxiety, fear, pleasure), reproductive functions (e.g., sexual and maternal behav-
iors), and social behaviors (e.g., recognition of cheat specifics, family, clan, or