An odour is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive by their sense of smell. An odour is also called a “smell” or a “scent”, which can refer to either a pleasant or an unpleasant odour. The perception of odours, or sense of smell, is mediated by the olfactory nerve. The olfactory receptor or cells are neurons present in the olfactory epithelium, which is a small patch of tissue at the back of the nasal cavity. There are millions of olfactory receptor neurons that act as sensory signalling cells. Each neuron has cilia in direct contact with the air. Odorous molecules bind to receptor proteins extending from cilia and act as a chemical stimulus, initiating electric signals that travel along the olfactory nerve’s axons to the brain. Odour perception is a primary evolutionary sense. The sense of smell can induce pleasure or subconsciously warn of danger, which may, for example, help to locate mates, find food, or detect predators.

Affrin Sulthana B

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