|
Anatomy => Sense Organs => Smell
Smell
Smell, one of the five special senses by which odors are perceived. The nose, equipped with olfactory nerves, is the special organ of smell. The olfactory nerves also account for differing tastes of substances taken into the mouth, that is, most sensations that appear introspectively as tastes are really smells.
Sensations of smell are difficult to describe and classify, but useful categorizations have been made by noting the chemical elements of odorous substances. Research has pointed to the existence of seven primary odors-camphorlike, musky, floral, peppermintlike, ethereal (dry-cleaning fluid, for example), pungent (vinegarlike), and putrid-corresponding to the seven types of smell receptors in the olfactory-cell hairs. Olfactory research also indicates that substances with similar odors have molecules of similar shape. Recent studies suggest that the shape of an odor-causing chemical molecule determines the nature of the odor of that molecule or substance. These molecules are believed to combine with specific cells in the nose or with chemicals within those cells. This process is the first step in a series that continues with the transmission of impulses by the olfactory nerve and ends with the perception of odor by the brain.
Back
|
