Olfactory system

The sensory system that detects airborne chemical molecules and supports smell through receptors in the nose and connected neural pathways.

Olfactory epithelium: A specialized nasal tissue containing olfactory sensory neurons and supporting cells. Its sensory neurons detect odorants entering the nasal cavity.
Olfactory sensory neuron: A bipolar neuron in the nasal epithelium whose cilia detect odorants and whose axon projects to the olfactory bulb. These neurons provide the system’s primary sensory input.
Flavor: The combined sensory experience of taste, smell, and other cues during eating and drinking. Retronasal smell supplies much of the aroma perceived as food flavor.
Gustatory system: The sensory system that detects tastants and supports the sense of taste. Taste is often confused with smell, but uses distinct receptors and pathways.
Combinatorial coding (olfaction): The principle that odor identity is represented by patterns of activity across multiple olfactory receptor types. It accounts for the system’s ability to distinguish many odorants with a limited receptor repertoire.
Olfactory receptor: A receptor protein on olfactory sensory neurons that binds odorant molecules. Different receptor proteins help encode the chemical features of odors.
Odorant: A volatile chemical molecule capable of stimulating olfactory receptors. Odorants are the airborne signals this system detects.
Anosmia: The complete loss of the sense of smell. It shows what happens when olfactory function is absent.
Trigeminal system: The sensory system carried by the trigeminal nerve, including facial touch, pain, temperature, and chemical irritation. It detects sensations such as pungency that can accompany, but are distinct from, smell.
Olfactory receptor gene: A gene encoding a protein that detects odorants in olfactory sensory neurons. The large receptor gene family raises questions about how genetic variation shapes smell.

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