smell components
The olfactory epithelium captures gases entering the nose, allowing the sensation of odors. It is made up of supporting cells and olfactory receptor cells, which individually process the gases into smells, provided that the stimulus is in a gaseous state and the stimulus is soluble in water. Strangely, some gases will be processed, but create no noticeable smell; these gases are referred to as being "odorless." Untreated carbon monoxide is a good example of this. There are several theories as to how exactly the cells determine how the gas will smell. One theory suggests that certain olfactory cells will take only specific odors, and another that the smell is determined by molecular weight and characteristics. Neither have proven conclusive as of yet.
