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Senses

can include a sore tongue among the range of symptoms.

Glossodynia
A condition characterized by a burning sensation on the tongue.

Benign migratory glossitis
This condition is characterized by irregular and inflamed patches on the tongue surface that often
have white borders. The tongue may be generally swollen, red and sore. Another name for this
condition is geographic tongue. The cause of benign migratory glossitis is unknown.
Risk factors are thought to include:
• Mineral or vitamin deficiencies
• Local irritants, such as strong mouthwashes, cigarettes or alcohol
• Certain forms of anemia
• Infection
• Certain medications
• Stress

Olfactory System

Olfaction is the sense of smell. In humans the sence of Smell is received in nasopharynx.
Airborne molecules go into solution on moist epithelial surface of nasal passage. An olfactory receptors
neuron sends an impulse via Cranial nerve I the olfactory nerve. Although 80-90% of what we think is
"taste" actually is due to smell. This is why when we have a head cold or stuffed up nose we have a
harder time tasting our foods.

Receptors

Humans have 347 functional odor receptor genes; the other genes have nonsense mutations. This
number was determined by analyzing the genome in the Human Genome Project; the number may vary
among ethnic groups, and does vary among individuals. For example, not all people can smell
androstenone, a component of male sweat.

Each olfactory receptor neuron in the nose expresses only one functional odor receptor. Odor
receptor nerve cells may function like a key-lock system: if the odor molecules can fit into the lock the
nerve cell will respond. According to shape theory, each receptor detects a feature of the odor
molecule. Weak-shape theory, known as odotope theory, suggests that different receptors detect only
small pieces of molecules, and these minimal inputs are combined to create a larger olfactory
perception (similar to the way visual perception is built up of smaller, information-poor sensations,
combined and refined to create a detailed overall perception). An alternative theory, the vibration
theory proposed by Luca Turin (1996, 2002), posits that odor receptors detect the frequencies of
vibrations of odor molecules in the infrared range by electron tunneling. However, the behavioral
predictions of this theory have been found lacking (Keller and Vosshall, 2004).

An olfactory receptor neuron, also called an olfactory sensory neuron, is the primary transduction
cell in the olfactory system. Humans have about 40 million olfactory receptor neurons. In vertebrates,
olfactory receptor neurons reside on the olfactory epithelium in the nasal cavity. These cells are bipolar
neurons with a dendrite facing the interior space of the nasal cavity and an axon that travels along the

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