Odor

An odor is a quality of a substance perceived through smell when airborne molecules activate olfactory receptors. Its character depends on molecular composition, concentration, and the sensory system interpreting it.

Olfactory receptor: A protein in olfactory sensory neurons that detects odorant molecules and initiates neural signaling. Different receptor activation patterns help distinguish one odor from another.
Odorant: A volatile chemical compound capable of activating olfactory receptors. Odorants are the airborne chemical inputs that produce odors.
Olfactometry: The measurement of odor detection or intensity using human assessors or instrument-based methods. It turns subjective odor judgments into standardized measurements.
Taste: A sensory experience produced when dissolved substances stimulate taste receptors in the mouth. Taste detects dissolved chemicals, whereas odor depends on airborne molecules.
Olfactory epithelium: A specialized tissue in the nasal cavity containing olfactory sensory neurons and supporting cells. Airborne odorants first meet the sensory neurons here.
Volatility: The tendency of a substance to enter the gas phase under given conditions. A substance must release molecules into air to be smelled at a distance.
Odor pollution: Unwanted smells in the environment that can cause nuisance or affect well-being. Persistent odors can signal emissions and create community complaints.
Pheromone: A chemical signal released by an organism that affects behavior or physiology in another member of its species. Pheromones are defined by their signaling function, not simply by having an odor.
Olfactory bulb: A forebrain structure that receives and organizes signals from olfactory sensory neurons. It begins transforming receptor activity into odor representations.
Olfaction: The sensory system that detects airborne chemicals and supports smell perception. Odor is a perceptual quality within this broader sensory process.

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