There is tremendous variation in the sensitivity of the olfactory systems of different species. Dogs, for example, have far superior olfactory systems than humans and can do remarkable things with their noses.

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Situated within the mucous membrane at the roof of the nasal cavity, olfactory receptor cells are specialized sensory neurons. As shown in side-view anatomical illustrations, they feature hair-like extensions that function as binding sites for odorants dissolved in mucus, initiating the sensory transduction process for smell before transmitting signals to the olfactory bulb.

Olfactory Receptor Cells

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

Olfactory signal transduction begins when an odor molecule binds to a specific receptor on the hair-like extensions of an olfactory receptor cell. This binding triggers chemical changes within the cell, which subsequently generate a signal that is transmitted to the olfactory bulb.

Olfactory Signal Transduction

Dogs' extraordinary olfactory abilities may be due to an increased number of functional genes for olfactory receptors. Dogs have between 800 and 1200 of these functional genes, compared to the fewer than 400 observed in humans and other primates (Niimura & Nei, 2007).

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