To detect an odor or scent by the olfactory nerve.
One of the five senses, the sense which is experienced through the nose.
The perception of odors and scents through stimulation of the olfactory (pertaining to smell) nerve in the upper portion of the nose. When special sensory cells in the nose are stimulated by tiny molecules in substances in the environment, the thin, sensitive fibers in the olfactory nerve convey these smell sensations to the olfactory bulb, located at the front of the brain, behind the nose. Common treatments to correct the loss of the sense of smell include surgery to open the nasal passages or medications to reduce nasal inflammation.
The sense of smell is picked up in the olfactory areas of the nose. Each of these is about 3 square centimetres and contains 50 million olfactory, or smelling, cells. They lie, one on either side, at the highest part of each nasal cavity. This is why we have to sniff if we want to smell anything carefully, as in ordinary quiet breathing only a few eddies of the air we breathe reaches an olfactory area. From these olfactory cells the olfactory nerves (one on each side) run up to the olfactory bulbs underneath the frontal lobe of the brain, and here the impulse is translated into what we describe as smell.
To perceive by stimulation of the olfactory nerves. The sense of smell is a chemical sense dependent on sensory cells on the surface of the upper part of the nasal septum and the superior nasal concha. These sensory cells live for an average of 30 days and are affected by a variety of factors, including age, nutritional and hormonal states, drugs, and therapeutic radiation.
One of the primary senses, smell involves hairlike extensions from scent receptor cells within the nasal mucous membrane. When these receptors are triggered by specific molecules, they relay signals along the olfactory nerves to the smell processing centers situated in the limbic system, as well as the temporal and frontal lobes of the brain, where the perception of smell occurs.
The inability to perceive odors can arise due to factors such as nasal membrane inflammation, often seen in common cold cases, or cigarette smoking. Other causes include hypertrophic rhinitis, where a thickened nasal membrane hampers olfactory nerve endings, and atrophic rhinitis, which involves the degeneration of these nerves. Head injuries that damage the nerves, as well as tumors located in the meninges (brain-covering membranes) or the nasopharynx (upper throat area), can also contribute to the loss of smell.
The experience of false and unpleasant smells could be associated with conditions like depression, schizophrenia, specific types of epilepsy, or during the process of alcohol withdrawal.