Britannica Sources used in this answer

How does the olfactory region in the roof of the nose detect smells?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Illustration showing different animals and their respiratory organs: a spider with book lungs, a chicken with lungs, a sponge with labeled inflow and outflow pores, a fish with gills, and a caterpillar with spiracles. — Respiratory system Different methods of respiration in animals.

The olfactory region, located in the roof of the nasal cavity, detects smells through a specialized process involving chemical interaction and sensory signaling.12

The lining of this region contains millions of olfactory receptor cells. Each of these cells features a peripheral dendrite that extends to the surface of the olfactory epithelium, where it terminates in a knob with fine, hair-like extensions called cilia. These cilia are covered by a thin layer of mucus.2341

When airborne chemical substances enter the nose, they dissolve in this layer of moisture. Once dissolved, these particles come into contact with the cilia and bind to specific olfactory receptor proteins. This binding triggers a conformational change in the protein, initiating a sequence of chemical events that alter the electrical potential across the cell membrane. This process generates action potentials, which are then transmitted via the olfactory nerve fibers through the bony roof of the nasal cavity to the olfactory bulb in the brain for processing.1243