The Olfactory System
Colleen Ziringer and Carla Kostek
Physical Stimulus
There are three ways in which to determine the odorants: through soluability, shape
and size of the molecules that are smelled. These molecules must be in a gaseous
state, water and lipid soluble. For the most part odors are mixtures of at least
two separate chemical compounds. For example, odors emitted by decaying matter such as
flesh and feces.
There are several different classifications of odors. Henning's smell prism is triangular
with six primary odors. These include fragrant, putrid, ethereal, burn, resinous
and spicy. Another classification is Crocker-Henderson system which only offers
four classifications of odor. These are burned, fragrant, acid and caprylic. In
addition the stereochemical theory identifies seven odors camphoraceous, musky, floral,
minty, ethereal, pungent and putrid. If molecules share geometric properties it
is likely that they share similar odors.
Receptors
Receptors are located in the mucous membrane, or epithelium. They are high on each
side of the nasal cavity and are relatively long and column shaped. It is estimated
there are 10,000,000 olfactory cells in the human. At one end of the receptors
are the olfactory cilia. They are immediately connected with the dendritic knobs and
the mucosa, which is the receptor site for odorants and are involved in the process
of relaying messages to the brain. The other end of the receptors contain the olfactory
bulb and continue the journey of these messages through the olfactory tract.
Web Sites
none yet!