How does the human sense of smell work? Why are women better at smelling than men?

Answer: The organ of smell is located in the nasal cavity at the beginning of the respiratory tract. It occupies an area equal to that of a small coin in the upper sinus and nasal septum.

The structure of the olfactory analyzer?

Answer: As is known, the olfactory region is located in the upper part of the nasal cavity, the so-called olfactory fissure. The space delimiting this area is the septum, the superior and middle conchae, and the cribriform plate. The mucous membrane covering this area differs from the rest of the mucous membrane of the nasal cavity by brown spots, which receive their color from the pigment contained in the olfactory cells: these spots or islands generally occupy 250 mm2 of area and have an irregular shape. There is no exact determination of the area of ​​distribution of the olfactory part of the nasal mucosa containing pigment; this area varies among individuals, sometimes occupying part of the superior turbinate and nasal septum, sometimes moving to the middle turbinate. The olfactory pigment is apparently similar to the pigment of the retina, and its disappearance leads to a loss of smell, which is observed in old people, in people with a disease of the epithelium of the olfactory fissure itself.

Where is the cortical center of smell located?

Answer: The central section is the cortical olfactory center located on the lower surface of the temporal and frontal lobes of the cerebral cortex. The olfactory cortex is located at the base of the brain, in the region of the parahippocampal gyrus.

Organ of taste

What is the taste organ?

Answer: Taste receptors consist of neuroepithelial cells, contain branches of the taste nerve and are called taste buds.

Taste buds (gemma gustatoria) have an oval shape and are located mainly in the leaf-shaped, mushroom-shaped and grooved papillae of the mucous membrane of the tongue (see section “Digestive system”). They are present in small quantities in the mucous membrane of the anterior surface soft palate, epiglottis and back wall throats.

Irritations perceived by the bulbs enter the nuclei of the brain stem, and then to the region of the cortical end of the taste analyzer.

Receptors are able to distinguish four basic tastes: sweet is perceived by receptors located at the tip of the tongue, bitter - by receptors located at the root of the tongue, salty and sour - by receptors at the edges of the tongue.

Where is the taste organ located?

Answer: The organ of taste (organum custus) is a peripheral section of the taste analyzer and is located in the oral cavity.

The structure of a taste analyzer?

Where is the cortical taste center located?

General body cover

What is the importance of skin for the human body?

Human skin has a complex structure and performs a number of important functions. It covers the entire surface of the body and reliably protects it from negative impact external factors. Due to the structural features of the epidermis, it prevents the penetration of pathogenic bacteria and harmful chemical compounds, water and various contaminants. In addition, the skin protects internal organs from mechanical injuries, temperature and other physical influences. Melanin, a special skin pigment, neutralizes the harmful effects of ultraviolet rays

Name the layers and appendages of the skin indicated by numbers in the figure?

stratum corneum

What formations perceive pain, where are these formations located?

Answer: Pain sensations are perceived by nociceptors

What formations perceive touch, where are these formations located?

Answer: The organ of touch perceives tactile irritations resulting from touching or pressing objects on the skin. Afferent innervation of the skin is carried out by nerve fibers coming from sensory neurons of the spinal ganglia. The dendrites of sensory neurons form tactile receptors that are found in the skin.

What formations perceive pressure, where are these formations located?

Answer: When the organs of touch and pressure are applied to the mechanoreceptors of the skin, the energy of the stimulus is transformed into nervous excitation, which is transmitted through a chain of neurons from the peripheral part of the skin analyzer to its cortical part - to the posterior central gyrus. The sensitivity of the skin of the legs is projected in the upper part, the sensitivity of the arms and torso is projected in the middle, and the scalp is projected in the lower part.

What formations perceive the feeling of heat, where are these formations located?

What formations perceive the feeling of cold, where are these formations located?

Olfaction is the process of perceiving the odors of substances. Elements that perceive odors of substances are located in the mucous membrane of the superior and partly middle nasal concha. These elements are represented by olfactory cells and receptors.

The structure of the human olfactory organs

Receptor cells have short (15-20 µm) peripheral processes and long central ones. The bodies of these cells are located in the thickness of the mucosa, the surface of which is 240-500 mm 2. Olfactory receptors constitute the chemical sense organ. In humans there are about 40 million, and in dogs, for example, many times more (about 225 million). This explains the high ability of dogs to detect odors.

The peripheral processes of the olfactory cells end in club-shaped thickenings. These thickenings at their apex contain 10-12 pointed hairs, consisting of 9 pairs of filaments. Olfactory hairs are a kind of antennas that actively interact with molecules of odorous substances.

It is believed that molecules of odorous substances settle on the surface of the nasal mucosa and dissolve in the secretion of glands, which are also located in the nasal mucosa. Substances dissolved in this way irritate the olfactory hairs and club-shaped thickenings. From here, impulses travel along the olfactory nerves to the olfactory centers of the brain located in diencephalon and bark. There the sensation of the smell of inhaled substances is formed.

The system of olfactory receptors, olfactory nerves and smell centers makes up the olfactory analyzer. This analyzer is less important for human life than vision and hearing. The loss of the sense of smell manifests itself in the inability to smell substances in the air (and they may be important for health), or to recognize spoiled food. For perfumery workers, Food Industry, food industry, loss of smell can cause a change in professions.

The senses are very important to all of us. A person’s sense of smell can make the perception of the world much brighter.

The role of the olfactory organ

The organ of smell is the nose, which serves us so that we can enjoy wonderful smells and aromas. He also warns us about various kinds dangers (fire, gas leak). A good sense of smell is very important for any person, since without it it is impossible to perceive the world 100%. So, with a poor sense of smell, life can become gray and dull, devoid of all colors.

The organ of smell is a tool for obtaining information; it helps a person to understand the world. It is known that children whose perception of smells is impaired cannot develop properly and lag behind their peers. The human olfactory organ is closely related to the taste organ. A very small loss of the ability to subtly feel and distinguish odors negates the pleasure of the tasty food. And people often choose their surroundings by smell. Probably no one will be able to communicate with a person for a long time if his aroma is not very pleasant.

The olfactory organ, helping us to perceive odors, is able to create mood and influence well-being. For example, cinnamon and mint scents can increase alertness and reduce irritability, while coffee and lemon scents can help promote clear thinking. The human olfactory organ has the ability to distinguish up to 10,000 aromas. This wealth given to us by nature must be treasured. None of the people wants to stop smelling flowers, herbs, forests, and the sea.

What is the sense of smell?

The ability to distinguish and perceive various odors of substances that are in environment, is the sense of smell. Recognition of odors usually provokes the emergence of various emotions. In this sense, the sense of smell often becomes more important than, for example, good hearing or excellent vision. The impact of various aromatic substances on the olfactory organ can excite the human nervous system. This, in turn, leads to changes in functions different organs and systems of the whole body.

Organ structure

The organ of smell is the nose, which perceives appropriate stimuli dissolved in the air. The process of smell consists of:

• olfactory mucosa;
• olfactory filament;
• olfactory bulb;
• olfactory tract;
• cerebral cortex.

The olfactory nerve and receptor cells are responsible for the perception of odors. They are located on the olfactory epithelium, which is located on the mucous membrane of the upper posterior part of the nasal cavity, in the area of ​​the nasal septum and the upper nasal passage. In humans, the olfactory epithelium covers an area of ​​about 4 cm2.

All signals from the receptor cells of the nose (of which there are up to 10 million) enter the brain through nerve fibers. There the idea of ​​the nature of the smell is formed or its recognition occurs.

In humans, there are olfactory and trigeminal nerves, to the endings of which odor receptors are attached. Nerve cells have two types of processes. The short ones, called dendrites, are rod-shaped, each containing 10-15 olfactory cilia. Others, the central processes (axons), are much thinner, forming thin nerves that resemble threads. These same threads penetrate into the cranial cavity, using holes in the plate for this purpose. ethmoid bone nose, and then join olfactory bulb, passing into the olfactory tract. The bulb lies at the base of the skull and forms a special lobe of the brain.

The visceral brain system, or limbic system, includes the cortical zones of the olfactory analyzer. These same systems are responsible for the regulation of innate activity - search, food, defensive, sexual, emotional. The visceral brain is also involved in maintaining homeostasis, regulating vegetative functions, formation of motivational behavior and emotions, organization of memory.

Peculiarity

The olfactory organ is capable of influencing the thresholds of color perception, taste, hearing, and excitability vestibular apparatus. It is known that if a person’s sense of smell sharply decreases, then the pace of his thinking slows down. The structure of the olfactory organ is special; it distinguishes it from other senses. All structures of the olfactory analyzer take an important part in organizing emotions, behavioral reactions, memory processes, autonomic-visceral regulation, and regulation of the activity of other areas of the cerebral cortex.

There are substances that have pungent odor(ammonia, vinegar essence). They are capable of exerting both an olfactory effect and an irritation on sensitive fibers trigeminal nerve. This explains the specificity of the formation of odor sensations. Respiration rate, pulse, and blood pressure can reflexively change under the influence of olfactory stimuli.

Organ sensitivity

The acuity of smell can be judged by the fact that a person is able to clearly perceive, for example, the smell of 0.0000000005 parts of a gram of rose oil or musk, approximately 4.35 parts of a gram of mercaptan gas. If the air contains even 0.00000002 g per 1 cm 3 of hydrogen sulfide gas, then it is clearly noticeable to us.

There are odors that are very powerful and persistent and can even be stored for 6-7 thousand years. An example of this is the smells that were felt by the people who participated in the excavations Egyptian pyramids. We can say that our nose is capable of detecting various impurities of odorous substances in very small quantities in the inhaled air, which cannot be measured even with the help of chemical studies. It has been proven that the acuity of smell depends on the time of day (smells are better sensed after sleep) and physiological state person. The sense of smell is more acute when a person is hungry, as well as during spring and summer.

The human olfactory organ is capable of distinguishing no more than several thousand different shades of odors. In this we are very far behind animals. Dogs, for example, can recognize about 500 thousand odors.

Smell and emotions

Brain research suggests that the hemispheres gradually formed from the olfactory brain in the process of evolution forebrain who are responsible for higher nervous activity. Smell is the primary source and way of transmitting various information among creatures in living nature. In addition, for all animals and for primitive man, the organ of smell is necessary for finding food, a sexual partner, warning of danger or marking a habitat.

For a person living in modern world, the main method of transmitting information becomes verbal, which was able to supplant all others that arose earlier. Odor is known to have a powerful effect on emotional sphere, as well as processes associated with it. This influence often occurs at the subconscious level. This experience in a person's life is not always positive. For example, manifestations of diseases in the form of psychosomatic diseases are recorded.

Great importance of smell

The functions of the olfactory organ are numerous in the life of all living beings, as it is able to warn of the danger of poisoning by poisonous gases that can enter the body through the lungs. It is also possible to control the quality of food consumed using smell, which protects against the entry of decomposed and poor-quality products into the gastrointestinal tract.

Conclusion

As a conclusion we can say that close connection long-term memory, emotions and sense of smell indicate that smell is a powerful tool impact on the entire human body and his worldview as a whole.

Smell I Smell (olfactus)

type of sensitivity directed to odors; carried out by an olfactory analyzer. The peripheral part of the olfactory analyzer is represented by receptor cells (olfactory epithelium) located in the mucous membrane of the upper posterior part of the nasal cavity (paranasal sinuses), in the area of ​​the superior nasal concha and the adjacent part of the nasal septum (in humans there are about 10 million of them, in dogs - shepherd dogs - over 200 million), and the olfactory nerve, formed by the axons of receptor cells. The olfactory end is in the olfactory bulb, where the second-order olfactory neurons are located. Their axons are connected to various parts of the so-called olfactory brain, which represents part of the cerebral hemisphere in the region of its lower and medial surfaces. In humans, oxygen plays a much smaller role than in animals and than other types of sensory perception, including hearing. Its role increases with blindness and especially deaf-blindness; At the same time, there is a compensatory development of olfactory sensitivity, expressed in the analysis of odors, and olfactory memory.

The reception of odorous substances is carried out by receptor cells. Their peripheral processes are equipped with club-shaped thickenings ending in a bunch of thin olfactory hairs (flagella or cilia) immersed in a layer of mucus. Olfactory hairs increase the total surface of olfactory cells tens of times. The primary interaction of odorant molecules with receptor cells includes several successive stages: the odorous substance is delivered through the air to the surface of the olfactory epithelium, dissolves in the mucus layer and binds to receptive sites on the surface of the olfactory epithelium, forming complexes with components of the cytoplasmic membrane of the cells. At the same time, the ionic membrane of the cells changes and develops. Signals from receptor cells nerve fibers enter the , where an impression is formed about the nature of the smell (quality, strength), it, etc. Many substances with a pungent odor (for example, formic and acetic acid), along with the olfactory one, have an effect that irritates the sensitive fibers of the trigeminal nerve, which determines the specificity of the formation of the sensation of smell. Olfactory stimuli can also reflexively change frequency breathing movements and pulse, . Of interest is the phenomenon of the so-called hematogenous olfaction (the appearance of a sense of smell after the introduction of an odorous substance into a solution), the mechanism of which has not yet been sufficiently studied.

For many odorous substances, perception is determined (the so-called olfactory threshold), i.e. the minimum substance capable of causing a reaction in the olfactory analyzer (the recognition threshold, when the quality of an odor is perceived, usually lies slightly above the O. threshold). O. thresholds for many substances are very low. , for example, senses one of the isomers of trinitrobutyltoluene (the smell of artificial musk) in a concentration of about 5․10 -15 g/ml(or 10 7 molecules per ml); for vanillin the threshold is 5․10 -13 g/ml(or 2․10 9 molecules in 1 ml). O. in humans is significantly higher than the O. threshold in animals (for example, in dogs, the O. threshold for butyric acid is about 10 4 molecules per 1 ml, and in some insects to sex pheromone - about 10 3 molecules per 1 ml). Normally, a person’s O. threshold undergoes fluctuations depending on the time of day and physiological state. O. changes are observed in women during menstrual cycle or during sex hormone therapy. to odors decreases with age. Sometimes healthy people with normal O. there is a noticeable decrease in sensitivity to a certain odorous substance or a small group of substances, for example, to musky odors. This phenomenon, called selective or specific anosmia, is apparently determined by genetic factors. A change in O.'s severity can be caused by pharmacological agents. Long-term exposure to irritants on the olfactory system can lead to the development of adaptation of O. After irritation of the olfactory analyzer, the threshold of O to the irritating substance (direct, or homogeneous) and, to a lesser extent, to other odorous substances (cross, or heterogeneous, adaptation) increases.

To study olfactory function, qualitative and quantitative olfactometry is used. Qualitative olfactometry, using sets of odorants that affect the olfactory (for example, phenylethyl alcohol, eugenol, citral), gustatory (pyridine, chloroform) and other types of sensitivity, is used to determine a person’s ability to perceive and distinguish odors. Quantitative olfactometry is carried out to determine the O. threshold, the time of adaptation and restoration of olfactory function using olfactometers, which allow dosing the intensity and duration of action of an odorous substance.

O.'s disorders can be of peripheral and central origin. In the first case, they are caused by pathological processes in the nasal cavity, incl. in the olfactory epithelium; in the second - damage to the olfactory analyzer for more than high level. O.'s violations are very diverse. A decrease in the perception of odors () up to its complete loss () is observed when chronic rhinitis, ozena, nasal polyposis, atrophy of the nasal mucosa old age, curvature of the nasal septum, incl. congenital, other malformations of the nose, with underdevelopment of the olfactory analyzer, lesions of the central nervous system. toxic nature (for example, with prolonged exposure to benzene and its derivatives, titanium), brain tumors, disorders cerebral circulation etc., as well as radiation sickness. Aggravated O. () develops with dysfunctions of both peripheral and central departments olfactory analyzer; it may accompany vegetative-vascular dystonia, hypothalamic syndrome. There may be distortions of perception (), olfactory, most often in the form of a bad smell (), inability to distinguish odors (impaired differentiation) and recognize them (impaired identification, or olfactory), as well as odor on the side opposite to irritation (). and olfactory hallucinations are symptoms of a neurodynamic nature, are unstable and are usually replaced by other disorders of the olfactory function (hyposmia, anosmia, impaired differentiation).

Various variants of O. violations should be taken into account when topical diagnostics brain lesions. In particular, parosmia is associated with pathology olfactory pathways and centers located mainly in the medial parts of the anterior cranial fossa (olfactory bulb, olfactory tract, olfactory triangle, anterior perforated substance); alloesthesia is observed during proliferation connective tissue within the olfactory bulb, olfactory tract, as a result of which nerve impulses along commissural fibers they pass to the opposite hemisphere. Impaired recognition and discrimination of odors occur with lesions of the nerve formations located in the middle cranial fossa (uncus, hippocampus, parahippocampal gyrus). Impaired odor recognition and olfactory hallucinations may occur in epilepsy. Olfactory hallucinations, parosmia and olfactory agnosia occur when pathological process in the area of ​​the cortical part of the analyzer. Slight hyposmia and severe olfactory agnosia are characteristic of tumors of the parietal and posterior frontal regions. temporal lobe, in addition, cause olfactory hallucinations.

Bibliography: Blagoveshchenskaya N.S. Topical meaning of hearing impairment, vestibular function, smell and taste in case of brain lesions, M., 1962, bibliogr.; Bracket A.A. Olfactory vertebrates, L., 1977, bibliogr.; Grinberg G.I. and Zasosov R.A. Fundamentals of physiology and methods of functional research of the auditory, vestibular and olfactory analyzers. L., 1957, bibliogr.

1. Small medical encyclopedia. - M.: Medical encyclopedia. 1991-96 2. First health care. - M.: Great Russian Encyclopedia. 1994 3. encyclopedic Dictionary medical terms. - M.: Soviet Encyclopedia. - 1982-1984.

See what “Smell” is in other dictionaries:

Olfaction, the sense of smell, the ability to detect the smell of substances dispersed in the air (or dissolved in water for animals living in it) [source not specified 672 days]. In vertebrates, the organ of smell is... ... Wikipedia

sense of smell- the ability to sense odorous substances, perceiving them as odors. Chemicals distributed in the form of steam, gas, dust and other things enter the nasal cavity, where they interact with the corresponding receptors. In addition to chemoreceptors, in... ... Great psychological encyclopedia

Cm … Synonym dictionary

SMELL, sense of smell, pl. no, cf. 1. One of the five external senses, the ability to sense and recognize smells. Subtle sense of smell. Olfactory organs. 2. Action under Ch. smell (rare). Dictionary Ushakova. D.N. Ushakov. 1935 1940 ... Ushakov's Explanatory Dictionary

The body's perception of certain properties (smell) through the olfactory organs. substances present in the environment. Animals inhabiting land perceive odorous substances (OS) in the form of vapors, and inhabitants of reservoirs in the form of water... ... Biological encyclopedic dictionary

sense of smell- SMELL, sniff, sense INHALATION, sniffing books. SMELL, inhale/inhale, sniff/smell... Dictionary-thesaurus of synonyms of Russian speech

SMELL, perception of odors. In humans and higher animals, it is carried out through chemoreceptors located in the mucous membrane of the nasal cavity, the signal from which enters the olfactory centers of the brain. Serves for animals... Modern encyclopedia

Perception of smells, a type of chemoreception. In humans and higher animals it is carried out through the olfactory analyzer (receptor nerve cells mucous membrane of the nasal cavity, olfactory nerves and olfactory centers of the brain).… … Big Encyclopedic Dictionary

Smell is one of the five senses accessible to people. In humans it is less developed than in most animals. This may be due to the fact that this sense does not determine our ability to survive, feed ourselves, find partners, etc. However, the sense of smell is the most sensitive of our senses. To stimulate the olfactory cells it is enough small quantity substances.

Human sense of smell

Our ability to smell is carried out by two in small areas odor detection cells, consisting of five or six million yellowish cells that are located high in the nasal passages.

For comparison, a rabbit has 100 million olfactory receptors, and a dog has 220 million. However, humans are able to detect certain substances in a diluted state, with a concentration of less than one part in several billion parts of air.

Children

Although the ability to identify odors is imperfect in childhood, even newborns are very sensitive to some important odors: recent research shows that newborn babies search for their mothers' nipples by smell. In the experiment, one breast of each participating mother was washed immediately after birth. The newborn baby was placed in the middle between the breasts. Of the 30 infants, 22 spontaneously chose the breast that had not been washed and retained body odor.

Other experiments have also shown that babies respond to very subtle differences in body aroma, but babies are thought to be very sensitive only to certain odors, not a wide range of them.

However, in terms of preferences, one large study found that three-year-old children have similar likes and dislikes to adults. Experiments conducted in the early 1970s and replicated in 1994 showed that children do not develop sensitivity to certain odors until they reach puberty. In these studies, 9-year-old children showed marked insensitivity to two musky odors, although their ability to detect other odors was the same as that of pubertal patients and adults.

Olfactory organ

To understand what smell is, we must talk about the organ responsible for this sense: the nose. The nose is part of our respiratory system, allowing us to inhale and exhale. On the other hand, in addition to breathing, the nose allows various aromas to enter from outside and, thanks to the olfactory receptors located in the nostrils, to perceive, feel and distinguish different aromas.

The human nose is actually the main organ of not only smell, but also taste. The tongue's receptors can only detect four tastes - sweet, sour, bitter and salty - all other "tastes" are detected by the olfactory receptors in our nasal passages.

Sense of smell: the process of smell

Although the smell process is more complex than any attempt to explain it, we could explain the smell process with the following steps:

• Molecules in the form of chemical compounds that are present in the air reach the nostrils and dissolve in the moist environment of the yellow mucous membrane.
• Once dissolved, the compounds chemically affect the olfactory receptors that detect odors.
• Activation of these receptors generates one of 12 pairs cranial nerves, nerve impulses that are sent directly to the olfactory bulb and from there to the cerebral cortex (where the “sense of smell” occurs).
• In the olfactory bulb, sensory receptors responsible for transmitting messages from aromas send information to two areas:
  1. frontal lobe;
  2. limbic system.
• The frontal lobe is responsible for scent recognition.
• On the other hand, the limbic system is associated with memory and emotions. When they receive nerve impulses from aromas, they cause powerful emotions, based on previous experiences, because the limbic system has access to situational memories, people, or places associated with perceived olfactory sensations.

Although our sense of smell is much less developed than that of animals, it still remains very sensitive, especially to unpleasant odors. Thanks to the structure of our nose, we can perceive bad odors more low concentrations than good ones.

Why is the nose sensitive to these odors? Overall, this is because it is an adaptive trait, as poor perception is associated with two basic emotions that favor our survival: disgust and fear. The perception of a bad aroma almost immediately causes avoidance of it.

For example, if upon entering your apartment you smell gas, you will immediately evacuate and call the police or fire department. Thus, the sense of smell activates processes that help us survive.

Attitude to memories

As we have learned, the sense of smell directly accesses our memory and our emotions. Of course, there are many situations, places or people with which we associate certain scents, and in the same way, these smells make us remember the stimuli associated with them.

We all know cases when, when accidentally inhaling a familiar perfume - in a store or on a walk - we suddenly remembered a person close to our hearts, or a situation connected with him.

Why is the sense of smell connected to our memories? Our sensitivity to smell, combined with our ability to associate stimuli, makes our sense of smell a direct link to our memory. The aroma of bread from the bakery can make us hungry, the smell of tangerines reminds us of the New Year, the scent of coffee reminds us of breakfast or work and, therefore, the infinity of associations between different smells and memories. These are some general associations, but each person creates his own associations.

It's clear that there are certain smells that can trigger very specific memories that can affect how we feel. Therefore, smells have an emotional component.

The sense of smell also allows us to appreciate the smell of things and people. However, not everyone smells like us, or not everyone is pleasant to our nose. In this way, we can differentiate between those bodies that have a smell and those that do not.

For the body to produce odor, it must release evaporative particles that enter our olfactory system. With this in mind, the more particles emitted, the more intense the body will smell.

Variations

Our ability to smell increases, reaching a plateau around the age of eight and declines in old age. Some researchers argue that our sensitivity to smell begins to decline long before we age, perhaps even after our 20s. One experiment suggests that decreased sensitivity to specific odors begins at age 15. But other scientists report that the ability to smell depends on the state of mind and physical health a person, and some very healthy 80-year-old people retain their sense of smell on par with young people. Women are more sensitive than men, which is confirmed by all the smell tests that were carried out as part of the research.

Those suffering from migraine, schizophrenia, depression, anorexia and very low weight often experience olfactory deficits or dysfunction. One group of researchers argues that some mental disorders are so closely related to specific olfactory deficits that smell tests should be part of diagnostic procedures. Zinc supplements have been shown to help treat some smell and taste disorders.

A recent study from the University of Pennsylvania suggests that, contrary to popular belief, blind people do not necessarily have a more acute sense of smell than sighted people. The determining factor here is training, which improves the performance of smell tests. Researchers from the University of Pennsylvania covered this topic in some detail - they developed a smell identification test, which has become a standard test used in almost all experiments.

The importance of "learning" in the development of odor sensitivity is supported by many other studies. Indeed, this factor can sometimes be a problem for researchers as subjects in repeated experiments become more adept at detecting the odors present.

Disorders

We can find some disorders that directly affect the sense of smell, especially leading to the loss of this sense. Here are some examples:

• anosmia: complete or partial loss of smell (permanent or temporary);
• hyposmia: decreased sense of smell;
• hyperosmia: very sensitive sense of smell;
• parosmia: the inability of the brain to correctly identify natural odor. Identifying neutral or pleasant odors as unpleasant;
• phantosmia: it's kind of olfactory hallucination, thanks to which people detect a smell despite its absence. They detect odors that are in currently No.

The sense of smell allows you to increase your ability to taste sensations, which is why many people who lose their sense of smell complain that they lose their taste. Although in most cases they can distinguish tastes like sweet, salty, bitter and sour.

Causes of disorders

Exist various reasons olfactory disorders. Loss of smell can occur due to conditions that make it difficult for air to reach the olfactory receptors located at the top of the nose, or due to injury or loss of these receptors. Loss of smell should not be permanent, although in some cases it may be a sign of other problems in the nervous system. Here are some common reasons:

• very often there is a temporary loss of smell due to colds, polyps, allergic rhinitis, infections respiratory tract, sinus infections, etc.;
• Due to aging, there may be a moderate decline in the sense of smell;
• smoking can also affect our sense of smell;
• head injury or other trauma, sinus or cranial surgery;
• hormonal changes;
• the impact of some chemical substances, such as solvents or insecticides, can negatively affect our ability to smell;
• some medications alter or minimize our ability to perceive odors (antibiotics, antihistamines, amphetamines, naphazoline, estrogens, phenothiazines, long-term use of nasal decongestants, reserpine, etc.);
• radiation therapy to areas such as the neck or head;
• disorders nervous system, such as Alzheimer's or Parkinson's disease.

Odor sensitivity researchers must be very careful about the odors they use in experiments because odor is not always a smell. Many odorous substances activate not only the olfactory system, but also the “somatosensory” system - nerve endings in our noses, which are sensitive to temperature, pain, etc. This is why patients who have completely lost their sense of smell can still detect menthol, phenylethyl alcohol and many other substances. A study that examined the abnormal ability to perceive odorants found that many so-called odors actually affected pain and temperature-sensitive nerve endings rather than olfactory receptors. Of the 47 “odorous” substances, people with anosmia could detect 45.