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the sense that enables one to perceive odors; it depends on the stimulation of sense organs in the nose by small particles carried in inhaled air. It is important not only for the detection of odors, but also for the enjoyment of food, since flavor is a blend of taste and smell. Taste registers only four qualities: salt, sour, bitter, and sweet; other qualities of flavor depend on smell. Called also olfaction.

The organs of smell are small patches of special cells (olfactory cells) in the nasal mucosa. One patch is located in each of the two main compartments of the back of the nose. The olfactory cells are connected to the brain by the first cranial nerve (olfactory nerve). Air currents do not flow directly over the patches in breathing; this is why one must sniff to detect a faint odor or to enjoy a fragrance to the fullest.

When one sniffs, air currents carrying molecules of odorous chemicals enter special compartments, called olfactory chambers, where the chemicals are dissolved in mucus. There they can act on the organs of smell in much the same way that solutions act on the taste buds of the tongue. The endings of the sensory nerves that detect odors, the olfactory receptors, can quickly adapt to an odor and cease to be stimulated by it after a few minutes of full exposure.

The sense of smell may be diminished or lost entirely, usually temporarily, as a result of an obstruction of the nose, nasal infection, injury or deterioration of the nasal tissue, brain tumor, or mental illness. In rare instances, injury or disease causes such damage to the olfactory nerve that loss of the sense of smell is permanent. Complete absence of the sense of smell is known as anosmia.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


1. The sense of smell.
2. The act of smelling.
Synonym(s): osmesis, osphresis
[L. ol- facio, pp. -factus, to smell]
Farlex Partner Medical Dictionary © Farlex 2012


(ŏl-făk′shən, ōl-)
1. The sense of smell.
2. The act or process of smelling.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


1. The sense of smell.
Synonym(s): smell (2) .
2. The act of smelling.
Synonym(s): osphresis.
[L. ol-facio, pp. -factus, to smell]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


The sense of smell or the act of smelling.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


the sense of smell, in which there is chemoreception of molecules suspended in the air.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005


1. Sense of smell.
2. Act of smelling.
[L. ol-facio, pp. -factus, to smell]
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about olfaction

Q. I have a very acute sense of smell. Most things that have a smell cause me to have Migraines every day. I have heard that a chiropractor is who I need to treat me for this problem. Anyone else here have this problem? What have you done and were you able to treat it?

A. I can't remember where I heard about the chiropractor's involvement but it is really unpleasant. I tend to make life unpleasant for others to, just not to have a migraine. Things like cooking popcorn, perfumes, trash and many other things will give me a migraine (not a headache) right away. It may be called Hyperosmia (abnormal sense of smell).

Q. MY friends body is leaking and he smells awful. He also has a skin rash. He stinks.Can I help him.He is big. smokes too much,and does shower but he still smells. I need to get him in a chairty hospital. If ignored what will happened. Thank You Bettye

A. HI betty,thank god he has a friend like you--I dont like saying this but,your friend is killing himself,and the sooner you try to get him into a hospital the better--it not going to be easy-but you can only try.At this point he is at risk of LUNG CANCER--A VERY BAD INFECTION--AND CARDIAC ARREST,because of his weight,eating is an addiction,and people die from it,also people die from respiratory arrest because of his weight--stay strong--mrfoot56

More discussions about olfaction
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References in periodicals archive ?
What is the Difference Between Orthonasal and Retronasal Olfaction and Why is it Important?
A recent longitudinal study has shown t hat older adu lt s wit h nor mal cog nition a nd difficulty in identifying odors are at greater risk of suffering dementia within 5-years than those with normal olfaction (Adams, Kern, Wrobewski, McClintock, Dale, & Pinto, 2017).
The sensory attributes evaluated by orthonasal and retronasal olfaction (n=14) are shown for four Finger Lakes Rieslings, with the number of instances recorded for each attribute marked.
The relationship between nasal anatomy and human olfaction. Laryngoscope 1988;98(11):1232-8.
(2013) described sensilla basiconica as compact, thick walled and arranged radially in the cuticular wall, and suggested olfaction as the likely function of this type of sensillum.
In a review published in Science, John P McGann, a neuroscientist who studies olfaction at Rutgers University, reveals how we ended up with this myth.
The sense of olfaction in all the living things of world is unique and special.
"Sidra's efforts through the conference are to bring together world-renowned experts from the fields of olfaction, taste, food perception and intake, and neurobiology of feeding to illustrate the ongoing research and to drive scientific knowledge in this area of research.
TORONTO -- A scratch-and-sniff test that asks subjects to identify 40 odors and ranks olfaction is almost as powerful a predictor of Alzheimer's disease as is a positive test for amyloid.
Aromas (odors) are the volatile chemical compounds perceived via the sense of smell (olfaction) through stimulation of receptor cells in the olfactory epithelium located in the upper reaches of the nasal cavity.
The aim of this retrospective study is to identify patients referred to a movement disorders clinic and clinician's private rooms who underwent initial evaluation of olfaction (using Sniffin Sticks smell discrimination testing) in addition to routine initial evaluation for motor Parkinsonism and other nonmotor symptoms and compared to the final diagnosis after longitudinal clinical follow-up according to standard criteria.
The researchers say their results "demonstrate an underlying genetic component detectable by mosquitoes through olfaction".