Climate and Weather Glossary of Commonly Used Terms And

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Reader's Note:

1. This limited and abridged glossary was taken from "The Cleaning, Remediation and Restoration Dictionary", 2014 published by Patrick Moffett. This abbreviated glossary has many of the common use terms used in fire damage assessment and remediation. However, due to size of the glossary, it is not designed to provide the reader with an entire glossary list of terms and definitions.

2. The glossary includes several components including general building construction, fire forensics, toxicology, environmental health, indoor air quality, OSHA and moisture related terms. This glossary has many mold related terms since fire damaged buildings are wet from putting out a fire. Therefore, when remediating char, smoke, odor and soot, the restorer must also dry a wet building including removing mold growth.

3. The glossary has a few cross-links to other terms. However, it does not provide you with source references and websites, which provides the reader with further information; they are found in "The Cleaning, Remediation and Restoration Dictionary", 2014 edition. The complete Dictionary is over 3,000 pages, where it has over 30,000 terms and definitions, cross-references, education notes and website links. Go to: www.RestorationDictionary.com

4. To contact the author email Patrick at [email protected]

Accessory olfactory system - A sensing system present in many vertebrates, this sensory system responds to pheromones. It is distinct from the olfactory system proper, containing a separate set of receptor neurons in the nose, located in a pair of structures known as the vomeronasal organ (also known as Jacobson’s organ). It is controversial whether humans have such a system. (See: Jacobson’s organ)

Ageusia (Agueusia) - Lack or loss of the ability to perceive taste.

The loss of the sense of taste, sometimes occurring in those patients who have a loss of the sense of smell due to blocked sinuses.

Analytical tests - Discriminative and descriptive tests conducted by trained sensory panels.

Androstenone - A steroid component present in the fat of sexually mature male boars. It is sensed by 35% of people as having a foul, urine-like, sweaty-type odor, by 15% as having a mild pleasant odor and by 50% as having no odor at all (see also specific anosmia).

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Anosmia - (1) No sense of smell. (2) Lack of olfaction, or a loss of the ability to smell. (3) An olfactory disorder characterized by the complete absence of any olfactory sensation. (4) The loss of the sense of smell, a side effect of the blockage of the anterior ethmoid sinuses, located between the eyes. (See: Partial anosmia; Specific anosmia)

Anosmia, functional - A person able to detect occasional odors but having no practical day-to- day sense of smell.

Aroma - Organoleptic feature that can be perceived by the olfactory organ, by retronasal way during tasting.

Balloon sinusplasty - With this procedure, done in a doctor's office under local anesthesia, a doctor can open up the sinuses much like a heart surgeon opens blocked blood vessels to the heart with balloon angioplasty.

Barosinusitis - Sudden pain in one sinus area due to swelling and closure of the opening to the sinus.

Basal cells - Cells of the olfactory epithelium that differentiate and divide to form new olfactory receptor neurons. Basal cells are located at the top of the olfactory epithelium, close to the cribriform plate. (See: Cribriform plate)

Bitterness - Bitterness is the most sensitive of the tastes. Common bitter foods and beverages include coffee, unsweetened cocoa, mate, marmalade, beer citrus peel, etc. Education Note: Among the most known bitter substances are Caffeine, MgSO4, Quinine HCl, Sucrose octaacetate, Urea, and Propylthiouracil.

Bitter-taste - It corresponds to the perception that remains in the mouth and throat after swallowing the product.

Bowman’s glands - (See: Olfactory glands)

Cacosmia - (1) An unpleasant form of parosmia. (2) An olfactory disorder in which a normal, pleasant odor is perceived as foul or putrefactive. For example, in one form of cacosmia, a subject smells rotting meat when no such odor is present.

Chemical sense - A sense modality in which chemical substances attach themselves to the receptors on the sensory cells (also known as chemoreception). Olfaction (including the accessory olfactory system) and gustation are chemical senses.

Chemoreception - (See: Chemical sense)

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Chemosensory - Relating to perception by a chemical sense.

CIE Lab - Color space that includes all perceivable color, with dimension L for lightness and “a and b” for the color-opponent dimensions.

Cilia - Tiny hair-like structures on the sinus membrane surface that help move mucus out of the sinuses.

Color (Colour) - Visual property corresponding in humans to the categories called red, blue, yellow, green and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors. Education Note: Color categories and physical specifications of color are also associated with objects, materials, light sources, etc., based on their physical properties such as light absorption, reflection, or emission spectra. By defining a color space, colors can be identified numerically by their coordinates.

Colorimetry - Science and technology used to quantify and describe physically the human color perception.

Conditions that affect the sense of smell - The following conditions can damage or even eliminate a person’s ability to smell or detect odors: 1) Medical Conditions: Head trauma, stroke, subdural hematoma, tumors, hemorrhage, infections, seizures and nerve damage, and Parkinson’s and Alzheimer’s diseases; 2) Physical Changes: Stuffy nose, colds, allergies, mouth breathing, dentures; 3) Aging and Genetics: Bone deformities, cleft palate, loss of receptors; and 4) Toxic Damage: Acids, solvents, insecticides, chemicals.

Cribriform plate - The light and spongy bone that separates the nasal cavity from the brain. The cribriform plate is also known as the ethmoid bone.

Cutaneous senses - Senses that include touch and everything else we feel through our skin: temperature, texture, pressure, vibration, and pain. For example, when we run our fingers over a rough surface, receptors in the skin of our fingertips send information about the surface’s texture to our brain. These receptors also sense whether the surface is hot or cold and whether it’s moving or stationary. In addition, nerve endings in our skin alert the brain to any painful stimuli, so if a surface is too hot we quickly move our hand away!

Decongestants - Decongestants are drugs that decrease nasal congestion by causing constriction of blood vessels and reduced blood flow to nasal passages.

Deviated septum - A variation in the vertical bone (septum) separating the right and left side of the nose.

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Descriptive tests - Evaluation of the importance of differences between various products.

Discriminative tests - Evaluation consisting of determining very small differences between various products.

Discriminant factorial analysis (DFA) - Computer-based data processing aiming for optimal separation of by maximizing inter-group distances and minimizing intra-group variability. This model is used to identify unknown samples into one of the training groups.

Dysosmia - (1) A non-specific term referring to a disturbance in the sense of smell. (2) Any olfactory disorder that is characterized by a distorted olfactory sensation—i.e. an illusory or hallucinatory olfactory experience. Education Note: Any disorder characterized by a lack of olfactory sensation in the presence of an odor stimulus does not fall into this category. (See: Cacosmia; Heterosmia; Phantosmia, Parosmia)

Electronic nose - An electronic device that detects odors and flavors. The working principle mimics human olfaction that functions as a non-separative mechanism: i.e. an odor or flavor, which is perceived as a global fingerprint.

Electronic tongue - An electronic instrument that measures and compares tastes. Using liquid sensor technology, the electronic tongue measure the global taste fingerprint of a product, as human tongue does.

Ethmoid bone - (See: Cribiform plate)

Eucalyptol - A colorless liquid that has a fresh camphor-like odor. Research suggests that 33% have a specific anosmia to eucalyptol.

Flavor (Flavour) - Combination of taste and aroma features.

Fragrance - Sweet or delicate odor.

Functional endoscopic sinus surgery (FESS) - Sinus surgery in which the surgeon uses a viewing device called an endoscope to look into the nose. This surgery removes blockages to the drainage areas of the sinuses.

Gas chromatography - A computer analysis method of separating the volatile chemicals of odors into their component parts.

Glomeruli - Structures within the olfactory bulb within which the axons of the olfactory receptor neurons and the dendrites of the mitral cells meet.

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Glomerulus - The glomerulus (plural glomeruli) in olfaction is a structure in the olfactory bulb as shown in the graphic on the preceding page. The glomerulus is the basic unit in the odor map of the olfactory bulb. Each odor activates a different pattern of glomeruli, such that simply by analyzing the different sets of activated glomeruli, one could, in theory, decode the identity of the odor. Education Note: This odor map, however, is modified by the circuitry within the olfactory bulb so that the spiking pattern of the second-order mitral cells is likely different from what is observed by looking at glomeruli activation (which, with most techniques, represents mostly pre-synaptic action-potentials in olfactory sensory neuron axons). (See: The olfactory system)

Gustation (Gustatory perception) - Also called taste, it corresponds to the sensation produced when a substance in the mouth reacts chemically with receptors of taste buds. Taste, along with smell (olfaction) and trigeminal nerve stimulation (which also handles touch for texture, also pain, and temperature), determines flavors, the sensory impressions of food or other substances.

Hedonic - Relative to pleasant or unpleasant feature. Hedonic tests, aimed at measuring the pleasant or unpleasant features of a product (affective assessment) are conducted by human sensory panels.

Heterosmia - An olfactory disorder in which all odorants smell alike.

Hyperosmia (Hyper/super-osmia) - (1) An enhanced sense of smell. (2) - An olfactory disorder characterized by an abnormal super-sensitivity to odors.

Hyposmia - (1) A reduced sense of smell. (2) An olfactory disorder characterized by a decreased sensitivity to odors.

Imaging - Capture, storage, manipulation, and the display of computer-based images.

Isovaleric acid - A natural fatty acid found in a wide variety of plants and essential oils. Specific anosmia to isovaleric acid is known as the ‘sweaty odor anosmia’ given its characteristic sweaty odor. Research suggests that 3% of people are anosmic to isovaleric acid—a relatively small percentage compared to those to isobutyraldehyde and androstenone. It, however, was the first reported form of specific anosmia. isobutyraldehyde: a colorless, flammable, liquid with a characteristic malty odor. Research suggests that 36% of people are anosmic to isobutyraldehyde.

Jacobson’s organ - (See: Vomeronasal organ)

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Limbic system - Consists of three structures in the brain: the olfactory cortex, the amygdala, and the hippocampus. The amygdala is thought to govern fear, emotion and mood. The hippocampus is responsible for memory storage. Education Note: The close proximity of these structures is thought to explain why olfactory sensations can evoke vivid memories and emotional responses.

Machine vision - Technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance in industry.

Mitral cells - The output neurons of the olfactory bulb that receive input from the olfactory receptor neurons.

Mitral cells, about - The mitral cells are neurons that are part of the olfactory system. They are located in the olfactory bulb in the mammalian central nervous system. They receive information from the axons of olfactory receptor neurons, forming synapses in neuropils called glomeruli. Education Note: Axons of the mitral cells transfer information to a number of areas in the brain, including the piriform cortex, entorhinal cortex, and amygdala.

Mucus - The material produced by the sinuses. Under normal conditions, the sinuses produce up to 1.5 liters of mucus a day. But allergy or other environmental triggers can increase mucus production and its characteristics.

Nasal cavity - The inside of the nose.

Nasal conchae - Three bony plates that project into each nostril. They function like turbines, churning the inhaled air as it passes through the nostrils. As it swirls around, the air is warmed and filtered by the mucosa covering the inside of the nasal cavity.

Nasal endoscopy - An examination of the interior of the nose and sinus drainage area with a special viewing device called an endoscope. Also called rhinoscopy or sinus endoscopy.

Nasal epithelium - The nasal epithelium, or the olfactory epithelium, is a specialized epithelial tissue inside the nasal cavity that is involved with the sense of smell. Education Note: In humans, it measures about 1 cm2 on each side and lies on the roof of the nasal cavity, about 7 cm above and behind the nostrils. It is the part of the olfactory system that is directly responsible for detecting odors.

Nasal steroid spray or drops - Treatments used to reduce tissue swelling in the nasal passages.

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Nasal polyps - Sinus tissue growths that can block the sinus passages and can lead to sinus blockage.

Nasal wash - A treatment involving a rinsing of the sinus passages with a saline solution made at home or bought over-the-counter.

Odor - (1) Conscious reaction to a chemical stimulus of the olfactory sense. (2) A chemical substance that has the capacity to stimulate the olfactory neurons or, more generally, the sense of smell. Most odorants consist of mixtures of different types of molecules.

Odor adaptation - The process by which one becomes accustomed to an odor. The adaptation time needed is greater when more than one odor is present. When adaptation occurs, the detection threshold increases. Education Note: The detection threshold limits change faster when an odor of high, rather than low, intensity is presented. Besides, adaptation occurs differently for each odor.

Odor detection threshold - The lowest concentration of a certain odor compound that is perceivable by the human sense of smell. The thresholds of a chemical compound are determined in part by its shape, polarity, partial changes, and molecular mass. (See: Threshold limit value)

“Odor Neutralization: Assessment and Removal” - A technical paper written by the author of this glossary and the Cleaning, Remediation and Restoration Dictionary. For more information about the technical paper go to: http://www.scrt.org/free-reports/doc_view/146-odor- neutralization-assessment-and-control and more information on the Cleaning, Remediation and Restoration Dictionary go to: http://www.restorationdictionary.com/

Odor threshold - A term used to identify the concentration at which animals respond 50% of the time to repeated presentations of an odorant. (See: Threshold limit value)

Odorant - A substance capable of eliciting an olfactory response: An odor is the sensation resulting from stimulation of the olfactory organs. Odors play an important part in our everyday life. (See: Odor)

Odorant and perception, about - An odorant is a substance capable of eliciting an olfactory response whereas odor is the sensation resulting from stimulation of the olfactory organs. Odors play an important part in our everyday life, from appetite stimulation to serving as warning signals for disease detection. A number of diseases have characteristic odors; these diseases include gangrene, diabetes, leukemia, and schizophrenia. Odors have been implicated in depression and nausea as well. Detectable odors can have a significant impact on people by affecting moods as well as having physiological impacts on the olfactory system. People

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

associate odors with past experiences and, from those experiences, involuntarily assess the odor as likable, dislikable, or indifferent. Effects on individuals, however, vary from one person to another. Most often, however, odor threshold is used to mean detection threshold, which identifies the concentration at which 50% of a human panel can identify the presence of an odor or odorant without characterizing the stimulus. The recognition threshold is the concentration at which 50% of the human panel can identify the odorant or odor, such as the smell of ammonia or peppermint. Although the detection threshold concentrations of substances that evoke a smell are slight, a concentration only 10–50 times above the detection threshold value often is the maximum intensity that can be detected by humans. This, however, is in contrast to other sensory systems where maximum intensities are many more multiples of threshold intensities. The maximum intensity of sight, for instance, is about 500,000 times that of the threshold intensity and a factor of 1 trillion is observed for hearing.

Odorant binding proteins - Proteins of the olfactory receptor neurons that recognize and bind odorant molecules, stimulating the cell to transmit signals to the olfactory bulb.

Off odor - Undesirable odor perceived by the nose coming from a variety of possible sources.

Off taste - Unwanted taste imparted by spoilage or contamination.

Olfaction (Olfactory perception) - Sense of smell mediated by specialized sensory cells of the nasal cavity. In humans, olfaction occurs when odorant molecules bind to specific sites on the olfactory receptors.

Olfactometer - A device that is used to measure olfactory detection thresholds and olfactory recognition thresholds. The olfactometer dilutes a selected concentration of an odorant sample with odorless air. Subjects then inhale the dilution and report whether they detect and/or whether they recognize the odorant sample.

Olfactory agnosia - An olfactory disorder characterized by a loss of the ability to recognize odors despite being able to detect them. Those who suffer from olfactory agnosia are unable to classify or contrast odors.

Olfactory axon - The fiber-like extension of the olfactory receptor neuron that transmits receptor signals to the olfactory bulb. Axons expressing the same receptor type join in sets of fiber bundles through which these signals are transmitted. Education Note: At the olfactory bulb, these signals are interpreted at the glomeruli and further signals are transmitted to the olfactory centers of the brain. (See: Limbic system)

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Olfactory bulb, about - In most vertebrates, the olfactory bulb is the most forward (rostal) part of the brain. In humans, however, the olfactory bulb is on the inferior (bottom) side of the brain. The olfactory bulb is supported and protected by the cribriform plate, which in mammals, separates it from the olfactory epithelium, and which is perforated by olfactory nerve axons. The bulb is divided into two distinct structures, the main olfactory bulb, and the accessory olfactory bulb. The olfactory bulb transmits smell information from the nose to the brain, and is thus necessary for a proper sense of smell. Its potential functions fall into the following four categories: 1) Enhancing discrimination between odors, 2) Enhancing sensitivity of odor detection, 3) Filtering out many background odors to enhance the transmission of a few select odors, and 4) Permitting higher brain areas involved in arousal and attention to modify the detection or the discrimination of odors. The processes of smelling and tasting begin when molecules detach from substances and float into your nose or into your mouth. In both cases the molecules must dissolve in watery mucous in order to bind to and stimulate special receptor cells. These cells transmit messages to brain areas where we perceive odors and taste, and where we remember people, places, or events associated with these olfactory (smell) and gustatory (taste) sensations. (See: The olfactory system)

Olfactory bulbs - Two pea-sized brain structures just above the nose in which axons from neurons that express the same odor receptor converge in associated glomeruli.

Olfactory cilia - Hair-like fibers on the end of the olfactory receptor neuron that are immersed in the olfactory mucosa and that contain the odor binding sites. Each olfactory receptor neuron is topped with an average of 10 cilia.

Olfactory detection threshold - The lowest concentration of an odorant required for detection against an odorless background.

Olfactory epithelium - (1) Two patches of tissue, each about the size of a dime, lying approximately 7cm within each nostril. Each patch contains three types of cells—olfactory receptor neurons, sustenacular cells and basal cells—and the olfactory glands that produce the olfactory mucosa. (2) A specialize epithelial tissue inside the nasal cavity that is involved in smell. Education Note: In humans, it measures about 1 cm2 and lies on the roof of the nasal cavity about 7 cm above and behind the nostrils. The olfactory epithelium is the part of the olfactory system directly responsible for detecting odors.

Olfactory fatigue - (1) The loss of olfactory sensation after exposure to a certain odorant. For example, consider how the smell of coffee ‘hits’ you when you walk into a café but fades, even disappears, as you sit. (2) An adaptation as the temporary, normal inability to distinguish a particular odor after a prolonged exposure to that airborne compound.

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Olfactory fatigue, about - Olfactory fatigue, or adaptation, is the temporary, normal inability to distinguish a particular odor after a prolonged exposure to that airborne compound. Olfactory fatigue can commonly be defined as adaption to constant stimulation of our sensory system for smell. Another example of this is the touch receptor cells in the skin. These cells adapt to the stimulation of our clothes, a fortunate thing, or they would distract us constantly. Adaption involves mechanisms at the level of the receptor cell, including the inactivation of ion channels in the membranes that generate the electrical signal. In a simplified explanation, after a stimulus causes a receptor cell to produce an electrical signal, the cell membrane soon stops allowing the ions to flow, thus preventing further signals. Removal of the stimulus followed by re-stimulation activates the process all over again. Odor fatigue occurs when total adaptation to a particular odor has occurred through prolonged exposure. This situation would apply to dairy milkers or dairy managers who are exposed to the smell of dairy manure on a daily basis and appear virtually unaware of the odor. While ammonia and hydrogen sulfide are odorants, and not odors per se, they are produced through processes often associated with odor, including municipal sewage treatment systems, coal burning, industries and factories, and livestock operations. Both ammonia and hydrogen sulfide can cause olfactory losses as a result of chronic or prolonged exposure by damaging the olfactory receptors. Ammonia also can affect the central nervous system. A number of other chemical pollutants, including some insecticides, result in losses in olfaction by damaging olfactory receptors. The use of medications may worsen chemosensory disorders. On average, olfactory receptors renew themselves every 30 days. Pollutants may alter this turnover rate or disrupt the integrity of the lipid membranes of olfactory receptors. Threshold levels have been identified for a number of pollutants above which odor or irritation occurs. Unfortunately, however, knowledge of the exact mechanisms by which pollutants alter olfaction is limited.

Olfactory glands - Glands of the olfactory epithelium which produce the mucus that bathes and protects the olfactory receptor sites (also known as Bowman’s glands).

Olfactory mucosa - A thin layer of mucus that bathes the olfactory epithelium, protecting the olfactory cilia and the olfactory receptor neurons located within.

Olfactory nerve - The entire collection of axon bundles originating from olfactory receptor neurons expressing the same olfactory receptor protein. These bundles project through the cribriform plate and converge in the glomeruli of the olfactory bulb (See: Olfactory axon)

Olfactory receptor neuron - Cell of the olfactory epithelium that contains the odor binding sites, or receptor sites. There are about 50 million receptor neurons in the human olfactory

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

epithelium. Each olfactory receptor neuron expresses one type of odor receptor. These neurons are unique in that they are the only neurons that regenerate.

Olfactory recognition threshold - The lowest concentration of an odorant required for its identification. The recognition threshold of an odorant is typically higher than its detection threshold. (See: Olfactory detection threshold)

Organoleptic - Qualifies the property of a product that can be perceived by human senses.

Organoleptic testing - Analysis of the properties of products and materials by means of the senses. Organoleptic testing is usually done by panelists and in this case is to a certain extent subjective, since perceptions among different persons as well as in a single person vary, depending on the state of the body. Education Note: Organoleptic testing can also be achieved by electronic sensing instruments such as electronic nose, electronic tongue or visual analyzer.

Palatability - Quality and pleasantness of the sensory attributes of a product that make it acceptable or agreeable to a consumer.

Parosmia - (1) A distortion of the sense of smell in the presence of a stimulus. (2) An olfactory disorder characterized by a distorted perception of an odor stimulus, i.e. an illusory perception of the odor stimulus; also known as troposmia. (See: Cacosmia; Heterosmia)

Partial anosmia - An olfactory disorder characterized by the inability to perceive some, but not all, odorants.

Partial least square (PLS) - In scientific measurement, this quantification model is aimed at predicting numerical values obtained by correlating sensing (sensory) instrument measurements with quantitative sample characteristics (substance concentration, descriptor intensity...).

Permissible exposure limit (PEL) - Sometimes referred to as the OSHA PEL, it is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent. For chemicals, the chemical regulation is usually expressed in parts per million (ppm), or sometimes in milligrams per cubic meter (mg/m3). Units of measure for physical agents such as noise are specific to the agent. PELs are established by OSHA. A PEL is usually given as a time-weighted average (TWA) although some are short-term exposure limits (STEL) or ceiling limits. Education Note: A TWA is the average exposure over a specified period of time, usually a nominal eight hours. This means that for limited periods, a worker may be exposed to concentrations higher than the PEL, so long as the average concentration over eight hours remains lower.

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Phantosmia (Phantom’ smells) - (1) An sensation of a smell in the absence of a stimulus. (2) An olfactory disorder characterized by the prevalence of olfactory hallucinations, such as: undergoing olfactory sensations (usually unpleasant ones) in the absence of an associated odorant.

Pheromones - A chemical produced by an organism that acts as a signal to other members of the same species. These chemical stimuli carry information about the sender such as gender, reproductive status and kinship.

Post-nasal drip - Drainage of mucus from the sinus that can collect in the back of the throat.

Principal component analysis (PCA) - In scientific measurement, the mapping of the multi- measurements of all samples on 2-dimension or 3-dimension graph that best highlights differences between samples. This model is used to explore the data and to assess discrimination performance.

Proboscis - The external part of the nose.

Receptor Cells - Olfactory receptor cells in the cell membranes of olfactory receptor neurons are responsible for the detection of odor molecules. Activated olfactory receptors are the initial player in a signal cascade, which ultimately produces a nerve impulse that is transmitted to the brain. Education Note: There are tens of millions of olfactory receptor cells but only about 2000 glomeruli. In a remarkable example of convergence, glomeruli receive input from 5,000–1,000 olfactory receptor cells but output onto only 10–25 mitral cells. By combining so much input, the olfactory system is able to detect even very faint odors.

Recognition Threshold - The concentration at which 50% of the human panel can identify the odorant or odor, such as the smell of ammonia or peppermint.

RGB - A color model in which the additive primary colors red, green, and blue light are added together in various ways to reproduce a broad array of colors.

Rhinencephalon - The whole of: the olfactory nerves and bulbs, their connections to various parts of the brain, and the limbic system.

Retronasal olfaction - The stimulation of the olfactory receptor neurons by molecules that originate in our mouths. When we chew, molecules are released from food. Some of these molecules travel up the retronasal pathway to the olfactory epithelium where they stimulate olfactory receptor neurons.

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Retronasal pathway - A passage at the back of the mouth that connects the mouth to the nose.

Retro-nasal olfaction - Odorant perception that goes up to the nasal holes after swallowing the product. This effect contributes to the taste of products for an 80% part.

Rhinoscopy - (See: Nasal endoscopy)

Saltiness - Saltiness is a taste produced primarily by the presence of sodium ions (e.g. NaCl). Other ions of the alkali metals group also taste salty, but the further from sodium the less salty the sensation is such as NH4Cl, CaCl2, LiCl, and KCl.

Secondary senses - Besides the five senses, secondary senses include balance, pressure, temperature, pain and motion. These senses along with the primary senses, help to keep our body in balance and adjusts our body systems. (See: The five senses)

Sense of smell, about - The sense of smell, or olfaction, is part of our chemical sensing system, along with the sense of taste. Normal smell occurs when odors around us, like the fragrance of flowers or the smell of baking bread, stimulate the specialized sensory cells, called olfactory sensory cells. Olfactory sensory cells are located in a small patch of tissue high inside the nose. Odors reach the olfactory sensory cells in two pathways. The first pathway is by inhaling, or sniffing, through the nose. When people think about smell, they generally think of this pathway. The second pathway is less familiar. It is a channel that connects the roof of the throat region to the nose. When we chew food, aromas are released that access olfactory sensory cells through this channel. If you are congested due to a head cold or sinus infection, this channel is blocked, which temporarily affects your ability to appreciate the flavors of food. Our sense of smell helps us enjoy life and helping us delight in the aromas of food to the fragrance of flowers. Our sense of smell is also a warning system, alerting you to danger signals such as a gas leak, spoiled food, or a fire. Any loss in our sense of smell can have a negative effect on our quality of life. It can also be a sign of more serious health problems. Education Note: It is reported, about one to two percent of North Americans experience problems with their sense of smell. Problems with the sense of smell increase as people get older, and they are more common in men than women. In one study, nearly one-quarter of men ages 60–69 had a smell disorder, while about 11 percent of women in that age range reported a problem. Many people who have smell disorders also notice problems with their sense of taste. To learn more about your sense of taste, and how it relates to your sense of smell, read the NIDCD’s Taste Disorders publication.

Sense of taste - Taste is the ability to respond to dissolved molecules and ions called “tastants”.

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Sense of taste, about - Humans detect taste with taste receptor cells. These are clustered in taste buds and are scattered in other areas of the body. Each taste bud has a pore that opens out to the surface of the tongue enabling molecules and ions taken into the mouth to reach the receptor cells inside. There are five primary taste sensations: salty, sour, sweet, bitter and umami. A single taste bud contains 50–100 taste cells representing all 5 taste sensations. Each taste cell has receptors on its apical surface. These are transmembrane proteins which admit the ions that give rise to the sensation of salty; bind to the molecules that give rise to the sensations of sweet, bitter, and umami. A single taste cell seems to be restricted to expressing only a single type of receptor (except for bitter receptors). A stimulated taste receptor cell triggers action potentials in a nearby sensory neuron leading back to the brain. However, a single sensory neuron can be connected to several taste cells in each of several different taste buds.

Sensory evaluation - Also referred as sensory analysis, this is a scientific discipline that applies principles of experimental design and statistical analysis to the use of human senses (sight, smell, taste, touch and hearing) for the purposes of evaluating consumer products.

Sensory panel - Group of persons that evaluate products by means of sense organs. There exist 2 types of panels: consumer panel and expert panel.

Septoplasty - Surgical procedure meant to straighten the nasal septum (vertical bone separating right and left sides of the nose).

Saline rinse - Rinsing of sinus passages with a saline solution, either bought commercially or made at home by mixing salt and water.

Shape - Characteristic surface configuration of an object.

Shelf Life Model - Mapping of the evolution of odor/taste/visual profile of products over time, as a distance to the fresh product at initial time.

Sinuses - Hollow air spaces within the cheekbones, between the eye, and in the forehead. Sinuses produce mucus, which normally drains into the nose. But if the drainage is blocked due to a cold or allergy, pain can result.

Smell - Organoleptic feature perceived by olfactory organ when sniffing some volatile substances (molecular mass < 400).

Soft independent modeling by class analogy (SIMCA) - This model is used to compare unknown samples to a reference. The model is built by taking into account one group considered

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

as the "gold reference". The model is going to identify unknown samples as belonging or not belonging to the one and only group previously defined.

Sourness - Sourness is the taste that detects acidity. Sour taste is detected by a small subset of cells that are distributed across all taste buds in the tongue. Acetic acid, citric acid, HCl, malic acid, and tartaric acid are typical sour substances.

Specific anosmia - An olfactory disorder characterized by the inability to perceive a specific odorant. Specific anosmias to androstenone and isobutyraldehyde are some of the most common.

Statistical quality control (SQC) - Model for statistical monitoring of product quality within an area of acceptable variability of this quality.

Sustenacular cells - Cells of the olfactory epithelium which support the olfactory receptor neurons.

Sweetness - Sweetness is one of the five basic tastes and is almost universally regarded as a pleasurable experience. Sugars are the substances the most commonly associated with sweetness, but other compounds also bring sweetness: Aspartame, Fructose, Glucose, Glycine, Saccharine Na, and Sucrose.

Taste - Sensations perceived by gustative organs (taste buds) when stimulated by some soluble substances.

The five senses - Touch, taste, smell and hearing. (See: Secondary senses)

The olfactory system - To understand how your sense of smell works—how your nose takes in smells and the olfactory system perceives them—you need a brief introduction to the anatomy of this system. The main parts of the olfactory system consists of: 1) Nasal epithelium, 2) Receptor cells, 3) Bone, 4) Glomerulus, 5) Mitral cells, and 6) Olfactory bulb.

Threshold limit value (TLV) - The TLV of a chemical substance is a level to which it is believed a worker can be exposed day after day for a working lifetime without adverse health effects. Strictly speaking, TLV is sometimes loosely used to refer to other similar concepts used in occupational health and toxicology. TLVs (along with biological exposure indices or BELs) are published annually by the American Conference of Governmental Industrial Hygienists (ACGIH).

“Odors and the Sense of Smell Glossary” of Commonly Used Terms and Definitions

Trigeminal sense - Corresponds to sensations perceived in the mouth or in the nose but not by taste buds or olfactory cells. These sensations gather tactile, thermal, painful and kinaesthesic sensations.

Trigeminal nerve - The largest of the cranial nerves, it is responsible for sensation in the face. Some trigeminal nerve endings extend into the nasal cavity. Education Note: Trigeminal nerve stimulation typically results in sensations of irritation but there is increasing interest in how stimulation of the trigeminal nerve endings located in the nasal cavity might contribute to perceived olfactory quality.

Troposmia - (See: Parosmia)

Turbinate - Structures within the nasal cavity, also called conchas that help to humidify and filter air as it passes through the nose.

Turbinate bones - (See: Nasal conchae)

Umami - A pleasant savory taste which is among the 5 basic tastes. The human tongue has receptors for L-glutamate, which is a source of umami flavor, as L-arginine, L-glutamine.

Vision - Human perception with the eyes.

Visual inspection - A common method of quality control, data acquisition, and data analysis using either human senses such as vision, hearing, touch and smell and/or an inspection equipment.

Volatile Organic Compounds (VOC) - Organic chemicals that have a high vapor pressure (low boiling point) at room-temperature conditions. They include both human-made and naturally occurring chemical compounds and are always composed of carbon and other elements such as hydrogen, halogens, oxygen, and sulfur. Education Note: Some VOC are odorant, some are dangerous to human health.

Vomeronasal organ - In some animals, an auxiliary olfactory sense organ utilized in the sensing of pheromones (also known as Jacobson’s organ). (See: Accessory olfactory system)