Olfaction, the sense of smell, is the one sense that can
provoke the fastest responses. Just walk into the kitchen while
your mother or father is preparing your favorite meal. Very likely,
you know what was cooking when you hit the front door, and your
mouth was watering by time you reached the kitchen. If have also
experienced the opposite reaction, whether someone dropped a stink
bomb, you smelled a particularly bad smelling perfume.
Odors, chemical molecules, floating in the air enter the
nose, dissolving in the mucous of the olfactory epithelium,
the membrane covering the superior (upper portion) nasal
cavity and septum. Here, olfactory cells bind
to the odors, sending a messages of delicious, noxious, or bland
smells through the olfactory nerves, then to the olfactory
bulb, which lies just on the other side of the skull, opposite
the foramen. From the olfactory bulb, the messages
of odors finally are sent to the brain.