Olfaction is the sense that gives people and animals an ability to smell. Human olfactory receptors, i.e. the sensory cells that register smell substances, are gathered in a small organ at the top of the nose, the so-called area olfactoria. This epithelium area consists of the olfactory nerve cells, supporting and basal cells.
Olfactory neurons have cilia which receptors are located on, in order to increase the surface of the epithelium. Each olfactory nerve cell is linked to only one kind of receptor. The tissue also contains glands that produce mucus to protect the cilia and also help to capture the fragrances. Insect olfactory organs tend to be placed on sensory whip. Olfaction area is located on top of the nasal cavity ceiling, at nervus olfactorius. It is an outgrowth of the brain that receive olfactory neuronal axion and connects them to the brain's nerve cells.
The olfactory organ in humans and other higher organisms can be thought of as a complex molecule detector and as well as a form of chemoreceptor. With the sense of smell, we can discern about 10 000 350 proteins and combinations of these, of which 80% are unpleasant smells.