The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. In humans, it measures about 1 inch wide by 2 inches long (about 2 cm by 5 cm) and lies on the roof of the nasal cavity about 3 inches (about 7 cm) above and behind the nostrils. The olfactory epithelium is the part of the olfactory system directly responsible for detecting odors. In zootomy, epithelium is a tissue composed of a layer of cells. ... The nasal cavity is a large air-filled space above and behind the nose in the middle of the face. ... Olfaction, the sense of odor (smell), is the detection of chemicals dissolved in air (or, by animals that breathe water, in water). ... The olfactory system is the sensory system used for olfaction. ... Odor receptors on the antennae of a Luna moth An odor (American English) or odour (Commonwealth English) is the object of perception of the sense of olfaction. ...

The tissue is made of three types of cells: the olfactory receptor neurons which transduce the odor to electrical signals, the supporting cells which protect the neurons and secrete mucus, and the basal cells which are a type of stem cell that differentiate into olfactory receptor neurons to replace dead receptor neurons. The olfactory epithelium is divided into four zones from ventral to dorsal. Each olfactory receptor is expressed throughout one zone. An olfactory receptor neuron, also called an olfactory sensory neuron, is the primary transduction cell for olfaction in the olfactory system. ... In physiology, transduction is the conversion of a stimulus from one form to another. ... Mucus is a slippery secretion of the lining of various membranes in the body (mucous membranes). ... Mouse embryonic stem cells. ... In zootomy, several terms are used to describe the location of organs and other structures in the body of bilateral animals. ... The word dorsal can refer to many different things. ...

The olfactory epithelium can be damaged by inhalation of toxic fumes, physical injury to the interior of the nose, and possibly by the use of some nasal sprays. Because of its regenerative capacity, damage to the olfactory epithelium can be temporary but in extreme cases, injury can be permanent, leading to anosmia. Anosmia is the lack of olfaction, or a loss of the sense of smell. ...