The senses of smell and taste are chemosenses and belong in the chemical sensing system.
The processes of smelling and tasting are complex. They begin when molecules are released by substances that stimulate the sensory cells in the nose, mouth, or throat.
Olfactory nerve cells are stimulated by odors. They are found in tissue located high inside the nose, and connect directly to the brain.
Gustatory nerve cells are stimulated by the taste of food and beverage. They are located in the taste buds of the mouth and throat.
These sensory cells transmit messages to the brain through the nerves, where specific tastes and smells are identified.
Another chemosensory process, called common chemical sense, also contributes to smell and taste. These cells alert the brain to sensations, such as heat (as from peppers) or cool (as from menthol).
How do taste and smell interact?
The four basic taste sensations are sweet, sour, bitter, and salty.
When these tastes, along with texture, temperature, and information from the common chemical sense, combine with odors, the perception of flavor occurs. Flavor defines the food that is eaten, and is recognized mainly through the sense of smell.
Source: National Institute on Deafness and Other Communication Disorders
The loss of the senses of smell (anosmia) and taste (ageusia) are the most common chemosensory disorders.
The reduced ability to smell (hyposmia) or to taste sweet, sour, bitter or salty substances (hypogeusia) are also common.
In other disorders of the chemosenses, odors, tastes, or flavors may be misread or distorted, causing a person to detect an unpleasant odor or taste from something that is normally pleasant to taste or smell. These disorders are important because they can have a significant impact on quality of life and be a sign of underlying disease.
Smell disorders are serious because they damage the early warning system that can alert a person to such things as:
Abnormalities in taste and smell can accompany or indicate the existence of diseases or conditions, such as:
Although some people are born with chemosensory disorders, most are caused by:
In addition to a complete medical history and physical examination, diagnostic procedures may include:
Specific treatment for smell and taste disorders will be determined by your doctor based on:
Treatment may include:
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