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

Explanation

When the agarbatti burns, it produces vapours having a characteristic pleasant smell. This smell is detected by the olfactory receptors present inside our nose. The action of smell of agarbatti on receptors sets off chemical reactions which generate electrical impulses.The sensory neurons carry these electrical impulses to the sensory area of forebrain (called cerebrum). This makes us detect the smell of burning agarbatti.