SMELL

Smell, or olfaction, happens when chemicals in the air enter the nose during the breathing process. Smell receptors lie in the top of the nasal passage. They send impulses along the olfactory nerve to the olfactory bulb at the base of the brain. Researchers theorize that there are a great many types of olfactory receptors. People perceive particular smells when different combinations of receptors are stimulated.
The sense of smell (olfaction) is carried by receptors that lie deep within the nasal cavity. In humans these receptors are confined to a patch of specialized ephithelium (olfactory epithelium,coverly roughly 5cm2 of dorsal posterior recess of the nasal cavity and lying over the turbinate cartilage.
The receptors are bipolar neurons that have a short peripheral process extends to the surface of the mucosa,where it ends in an expanded olfactory knob.