How do we detect the smell of an incense stick (agarbatti)?

Agarbatti produces vapors on burning and generates a characteristics a fragrance which is detected by the olfactory receptors present in the nose. The electrical impulses are generated by the action of smell of agarbatti which sets off chemical reactions. Cerebrum, a sensory area present in the fore brain, receives these electrical impulses by which we can identify the smell of burning agarbatti.