How do we smell? The nose is the organ of smell “How we smell different smells
Smell is a property of a substance. In the air, various odors spread due to a phenomenon called diffusion (similar to spreading, mixing one liquid in another). A person’s perception of odors is directly related to the particles of substances that emit these odors.
A person can perceive up to 400 thousand different smells. Odors are not classified, but are called by the name of the substance that emits them (for example: “the smell of perfume”, “the smell of flowers”, “the smell of food”, etc.).
Substances that have an odor tend to be absorbed. This explains the fact that our clothes are often saturated with various types of odors (perfume, smoke, food, etc.).
The sense of smell helps a person to protect himself from various impurities in the air when inhaling it, and to determine the quality of the air he breathes.
A person smells only when he inhales. This is easy to check. If you bring some object, the source of the smell, to your nose and hold your breath, you will not smell it.
The organ of smell is located in the uppermost part of the nasal cavity and its surface area, in almost every person, does not exceed 5 square centimeters. If you express a desire to feel a particular smell well, then take several short but sharp breaths in a row. This is due to the fact that during such inhalations, the air with vortex movements reaches the olfactory organ well and the smell it carries is felt quite strongly.
As you can see, the sense of smell plays a very important role in a person’s life, and sometimes can play a decisive role.
I. P. Pavlov believed that the problem of smell and odor is one of the most difficult in physiology and general biology. A person perceives smells through the nose. It is capable of perceiving and recognizing 4,000 different odors, and a very sensitive nose - up to 10,000, and special signals are transmitted to the brain about each individual smell. The olfactory nerves are almost never wrong. They won't transmit a lily signal when the air smells like a rose. Animals distinguish odors even better than people. Cats, dogs and horses have a developed sense of smell so strongly that, with a fair wind, they can distinguish the smell of a person they know from an entire block away. In wild animals, the sense of smell is developed and even stronger. The numerical magnitude of the nose's sensitivity to odorants is simply incredible. For example, an ordinary person smells vanillin at a concentration of 1 gram in 10 million cubic meters of air.
Aromas from the air enter the nasal cavity to the olfactory cells (about 30 million neurons). There are receptors on the surface of these ciliated cells. An impulse in the cell occurs when 8-10 molecules of an aromatic substance hit the receptors of the cilia. The sensation of smell occurs if at least 40 neurons are simultaneously excited. Even to perform such a seemingly simple task: how we distinguish smell, more than 6 million neurons are involved, each of which receives perhaps 10,000 contacts from its comrades. The odor signal travels through special cells directly to the hypothalamus of the brain. This is very important because this tiny organ regulates dozens of body functions such as temperature, thirst, hunger, blood sugar, sleep, sexual arousal and emotions such as anger and joy. At the same time, the odor signal is sent to an area called the Hippocampus, the part of the brain responsible for memory and attention. For this reason, smells are the most evocative of our memories. The world of smells surrounds us everywhere and continuously. Dozens of irritants penetrate the human nasal cavity every minute. However, we distinguish only some of them consciously. Most reactions to surrounding odors are subconscious.
Humans perceive only five basic odors.- mint, camphor, floral, ethereal, musky. All others are obtained by mixing the main ones.
Conscious reactions to smell- this is when the brain processes a numerous stream of information signals (highlighting the most vital), sends a return signal to which a person reacts (the smell of food or gas).
The mystery of the smell has not been completely solved, since scientists have not paid enough attention to it. One of the most interesting features of smell is the ability of this non-directional sensation to evoke a directional response. Animals with a pair of ears can determine the direction of sound very accurately. Even with the help of one ear, the animal can determine which side the sound is louder. Hearing is directional, like vision, but smell, like the sense of taste, has no direction.
There were more than 3 theories of smell. The greatest debate was caused by the question of whether the aroma molecule should come into contact with the receptors, or whether it emits waves that irritate the receptors.
Eymur's (key-lock) theory explains the smell as follows:“If the molecule is round, then the corresponding nerve receptor has a concavity into which the molecule fits.” However, Boston University neuroscientist John Cowhera discovered that this theory was flawed. In an experiment using a tomograph, Kawera discovered that three closely related chemicals—acetic acid esters, propyl acetate, and amyl acetate—whose molecules have similar shapes, caused different brain cell activity.
Recently, a young British biophysicist, Luca Turne, put forward a completely different concept of the mechanism of odor perception. According to this concept, smell, like color or sound, is determined by the frequency of vibrations, and the olfactory organ is like a device that is capable of recording these frequencies. Turn proved that different substances with different frequencies of interatomic vibrations have a similar odor. For the experiment, hydrogen sulfide and boron water were taken with an oscillation frequency of 2500 Hz. It turned out that boletus also smells of hydrogen sulfide, despite the fact that their molecules have different shapes.
American microbiologist Linda Buck may write a new page in the theory of smells. She managed to identify the gene in the human chromosome set that is responsible for olfactory receptors.
Lesson No. 4 Nose - the organ of smell “How we smell different smells”
Target: will introduce you to the features of the nose, give a comparative description of its work on the perception of odors in animals and humans; together with children, formulate recommendations for the protection of this important organ of smell.
Material: a vase of flowers, products with a characteristic smell, fabric bags, toilet soap, a bottle of perfume, pictures of some animals.
Progress of the lesson
At the beginning of the lesson, the teacher identifies children’s knowledge about the work of the nose, then summarizes the information.
Teacher's story: Some people believe that the nose is an ornament on the face. Others think that nature gave us a nose to lift it up. There are even expressions: “Look, you turned your nose up!” or “Why are you hanging your nose?” It's a joke.
In fact, even the smallest nose is a very important part of the body. We breathe through our nose. The nose also helps to sense and distinguish smells. How does the nose smell? The air we inhale irritates the nerve endings; if it has any odor, we will immediately feel it.
Experience No. 1
Target: Exercise children in distinguishing colors and food by smell.
The adult invites the child to determine without looking which vase contains roses and which contains lilies of the valley. You can use various products with a characteristic smell (black and white fresh bread, fresh strawberries or oranges, onions or garlic, cutlets or fish, etc.).
The teacher continues the story: Cells that perceive odors are extremely sensitive, they are able to distinguish thousands of different odors, and a special signal is transmitted about each individual smell. Most animals smell better than humans.
Cats, dogs and horses have such a strong sense of smell that they usually recognize the scent of someone they know long before they approach.
In wild animals, the sense of smell is even better developed. Deer and rabbits smell a predator from a great distance and manage to run away or hide.
When we have a bad runny nose, we almost stop smelling, this happens because the mucous membranes in the nose become swollen, irritated and clogged with mucus.
As a result, odors cease to excite the olfactory cells. In humans, odor-sensing cells are located in the uppermost part of the nasal cavity. Therefore, in order to smell it, you need to inhale. Let's verify this by experience.
Experience No. 2
Target: prove the need for inhalation to determine the smell.
The teacher places in front of each child a thick cloth bag, inside of which a piece of toilet soap or a bottle of perfume is hidden.
Without touching the bag, the teacher invites the children to guess what is inside by smell.
After the children’s answers, the teacher clarifies: in order to feel and identify the smell, you need to take several deep breaths in a row.
The teacher continues the story: With the help of smell, a person controls the air quality. When a pleasant smell appears in the air, we try to breathe deeper (air after rain, while walking in the forest, etc.). And when we feel an unpleasant odor, we try to breathe as little as possible. But within a short time the person gets used to the new smell and begins to breathe at a normal rhythm.
Scientists have calculated that a person distinguishes a huge number (400) of different odors. And yet, in most animals, the apparatus for distinguishing odors is much better developed. For many animals, smell is the most important sense, often replacing sight or hearing. For some of them, not being able to smell the scent of a predator or not finding prey on the trail is tantamount to death.
Dogs perceive odors better than other animals, birds perceive odors very poorly, but dolphins do not distinguish odors at all.
People perceive each other through sight and hearing during conversation.
But for animals, the peculiar smell coming from them plays a very important role. For example: ants have a “smell of alarm” and a “smell of death” which comes from dead ants. A living ant emitting this smell is “buried” by its fellows - pulled out of the anthill, and no matter how many times it comes back, “the funeral will be repeated until this smell disappears.
Yu. Prokopovich
“Why do babies need a nose?”
There are directspouts ,
Eatsnub noses...
I really need every nose
Since he has grown to his face.
Hot summer on a meadow
Nose smells flowers .
In the clearing - strawberries,
There are ripe strawberries in the garden.
The nose smells in the garden
Where the garlic and onions have grown.
This can happen in the house
The spout will also come in handy :
He will find jam in the cupboard,
Where are the candies and cookies?
Where are the chocolates in the buffet?
Or the juice in the bottle is sweet.
Who brought the oranges?
Everything will be sniffed out by our nose.
He even remembers what it's like
The smell of my mother's perfume.
Z. Moshkovskaya “My wonderful nose”
I do not know anything.
And suddenly
My nose
Speaks,
That somewhere
And someone
Something
Now
It'll burn!
I do not know anything,
I'm sitting in the stuffiness
Nose says:
– Let's take a walk!
I beg you very much!
You go with him
And you walk.
He speaks to me.
He says:
– You know, it already smells like spring!
Summary of a kindergarten lesson on cognitive activity.
How we smell different smells.
Objectives: to introduce the features of the nose, its structure;
Material:
Schematic representation of the nose;
Drawings of profiles of different nose shapes;
Containers containing various odorous substances: lemon, garlic, soap, geranium leaves;
Small mirror.
Experiments carried out in class:
Identifying objects by smell.
Determination of nasal functions.
Activation of vocabulary: nasal cavity, nasopharynx.
Progress:
Educator: - Children, guess the riddle: among the two luminaries in the middle, I am alone. Right! This is the nose. Some people believe that the nose is just an ornament on the face. Others think that our nose is needed to hold it up. There is even such an expression: “Look, you turned your nose up.” “He turns his nose up” - this is when a person is proud of something or boasts. Show me how it is! And “hanging his nose” is when someone is sad and offended. Show me how it is.
In fact, even the smallest nose is a very important part of the face: we breathe through our nose, and the nose also helps to distinguish odors.
Experience 1:
Take the cups (the container is closed, there are holes in the lid) and, without opening them, try to guess what is inside. To do this, bring the glasses closer to your nose and inhale deeply. Well, what's in your glass? (Children's answers). Now open it and check if you have identified the smell correctly.
Experience 2:
Now pinch your nose with your fingers and try to inhale the smell through your mouth. Did you smell it? No? And why? Because the nose determines the smell!
Experience 3:
Pinch your nose with your fingers and try to say: “They dropped the bear on the floor, they tore off the bear’s paw.” Tell me, was it difficult for you to speak with your nose closed? You can inhale and exhale with your mouth, but it is difficult to speak.
Educator: - Look at the picture: inside the nose there are two channels, the nasal cavity, which passes into the nasopharynx, connecting to the throat and ears. Inside the nose there are villi and mucous membranes. They clean the incoming air from dust. When air passes through the nasal passages, it warms up. And if you inhale air through your mouth, it gets cold into your throat and you can catch a cold. Your neck will hurt. In the upper part there are nerve endings that distinguish odors. When your nose is clogged with mucus during a cold, you can’t smell anything and it’s difficult to breathe.
Now look in the mirror, and then at each other. Do you have the same nose?
Children determine that their noses are different: straight, snub, “button”, “potato”. The teacher reads the poem “There are snub noses...”.
Educator: - Guys, why do we need a nose? How should you take care of it? And I’ll also tell you a secret that your nose definitely looks like your mother’s or father’s. At home, look in the mirror with your parents, and tomorrow tell me whose nose you have.
At the end, the game “Find the flower by smell” is played.
One child is blindfolded and asked to find the smell of geranium - the flower that has the strongest smell.
Why does my body smell like fish? Sweating is a natural process that performs important life support functions for the body:
- regulation of body temperature;
- removal of toxic substances;
- skin cleansing.
The smell of sweat is specific for each person, but if hygiene standards are observed, it is quite natural and does not cause unpleasant sensations. Unpleasant odors may appear when taking certain medications as a result of illness. This is due to the excretory function of the skin, which through the pores, together with the liquid base, removes some waste products that have a specific odor.
Causes of unpleasant odor
Changes in body odor can be caused by natural causes, such as:
- excess weight;
- eating too spicy and spicy foods;
- high level of sex hormones in the body;
- wearing clothes and shoes made of synthetic fabrics;
- representatives of some nationalities and races may have a specific smell;
- in women during menstruation, the smell may change;
- in adolescents during puberty.
These points can be easily corrected, or they will need to be taken into account in everyday life. It is much more important to pay attention to the smell of sweat, which indicates a disease.
Thus, a change in “aroma” may occur due to the development of:
- tuberculosis;
- diabetes mellitus;
- diseases of the digestive system;
- heart problems;
- kidney diseases;
- hormonal abnormalities;
- oncological diseases.
The smell that appears may have different impurities:
- acetone;
- rotten apples;
- ammonia;
- fish;
- very sour;
- rotten eggs;
- pear;
- cat urine;
- bitter;
- fresh bread and others.
Why does a fishy smell occur?
Before you begin to solve a delicate problem, you need to decide why your sweat smells, and then take appropriate measures.
The appearance of a fishy odor from the body, while observing normal hygiene requirements, does not always indicate a person’s active consumption of seafood or vitamins and dietary supplements containing a type of vitamin B - choline; much more often it signals problems with the functioning of internal organs.
One of the reasons may be a dysfunction of the liver, as a result of which a person lacks choline. Sweat smells like fish due to a hereditary metabolic disease - trimethylaminuria, in which the patient’s body does not absorb trimethylamine, which comes from food rich in choline (eggs, liver, soy, beef and others). This substance is excreted from the body in large quantities along with urine and sweat; even the breath of people suffering from this disease has a specific “fishy spirit”.
In women, the pathology is much less common than in men, but it actively develops in them during puberty, causing difficulties in communication and problems with the opposite sex.
The cause of the development of the disease is a defect in the FMO3 gene, which controls the process of converting digestive products into odorless substances. In the absence of this gene, the liver is unable to break down trimethylamine N-oxide, which causes a fishy odor. As a result, this substance is released with human waste products: sweat, urine, exhaled air.
Moreover, the carriers of the disease themselves do not feel the unpleasant odor emanating from them. At the same time, they have problems with communication and work in a team, since the people around them think that they stink, often such patients are forced to work from home.
When the smell of fish from the body is accompanied by pain in the abdominal cavity or genitals, discomfort during defecation or urination, and the appearance of blood in waste products, it indicates the presence of diseases of the digestive system: chronic constipation, diarrhea, urinary incontinence.
Any of these diseases is quite dangerous and can cause serious consequences, so if such signs appear, you should consult a doctor. First of all, you need to go to a gastroenterologist, who can prescribe an additional consultation with the following specialists:
- endocrinologist;
- gynecologist;
- proctologist;
- urologist.
If an unpleasant odor appears in the urine, you should visit a therapist who will prescribe clinical tests:
- blood and urine tests;
- taking smears from the vagina and urethra;
- bacteriological urine culture;
- biochemical blood test;
- detection of infectious agents using polymerase chain reaction;
- other tests.
Held:
- Ultrasound of the pelvic organs, kidneys, pelvis, ureter, urethra and bladder;
- cystography;
- X-ray of the pelvis and kidney area.
Elimination of unpleasant odor
If the causes of the problem are related to poor nutrition or failure to comply with certain hygiene rules, then this can be easily solved. It is enough to reconsider your diet, wardrobe and daily routine. You should exclude or reduce the amount of foods high in protein consumed from the menu:
- beans and all legumes;
- eggs;
- liver;
- seafood;
- dairy products;
- meat.
Properly selected clothing, which should be made from natural fabrics that allow the skin to breathe, be of the appropriate size and comfortable to wear, can help get rid of discomfort.
You need to take a shower regularly, especially after sports activities, and you don’t have to use soap every time; sometimes it’s enough to wash off the sweat from your body. Many experts advise giving preference to natural-based cosmetics that are less aggressive towards the natural human microflora. It is necessary to be careful when visiting beaches and solariums, which can cause damage to the upper layers of the skin.
At the same time, regular exercise and visiting the sauna allow you to remove excess metabolic products, cleansing the pores of the skin, as a result of which sweat becomes less “smelly”, but do not forget about a sense of proportion.
One of the proven folk methods–taking baths with a decoction of oak bark, wormwood, sea salt or a solution of potassium permanganate.
An important point is the removal of hair on the body, including in the armpits and groin area, since it is on the hair that sweat usually accumulates, which then begins to smell.
If the cause of the fishy smell is diseases of the digestive system, then it is necessary to focus on their treatment, and only then on additional measures.
At the same time, for people suffering from trimethylaminuria, the prognosis is unfavorable. There is no cure for this disease, so it cannot be eliminated. The patient can improve the situation a little with the help of diet, temporary use of antibiotics, and avoidance of situations that cause sweating.
As an auxiliary agent, it is recommended to use soap with a pH of about 5.5. Activated carbon and copper preparations can be taken internally. Naturally, carefully monitor hygiene, regularly change your underwear and epilate your body, which will somewhat reduce the unpleasant odor.
The use of deodorants in this case is an additional, but not very effective measure, since the drug does not eliminate the cause itself, but only temporarily masks the odor.
Smell is one of the senses a person needs to live a full life. And its violations impose tangible restrictions on the emotional state and become a real problem. Among the disorders of smell, there are also those when the patient is haunted by a smell that actually does not exist. Everyone is interested in the question of the origin of unpleasant symptoms, but only a doctor can help determine the source of disorders in the body.
Smell is perceived through the reaction of olfactory receptors located in the mucous membrane of the nasal cavity to certain aromatic molecules. But this is only the initial section of the corresponding analyzer. Next, the nerve impulse is transmitted to the areas of the brain responsible for the analysis of sensations (temporal lobes). And when a person smells odors that are not there, this clearly indicates some kind of pathology.
First of all, you should divide all the reasons into two groups. The smell may be very real, but is not felt by others until the patient speaks to them at close range. This is likely in the following situations, covering the practice of ENT doctors and dentists:
- Fetid runny nose (ozena).
- Sinusitis (sinusitis, sinusitis).
- Chronic tonsillitis.
- Caries, pulpitis, periodontitis.
These diseases are accompanied by the formation of pus, which gives an unpleasant odor. A similar situation may occur in those who suffer from diseases of the gastrointestinal tract (gastritis, peptic ulcer, cholecystitis and pancreatitis). Food that enters the digestive tract is processed less well, and during belching or reflux, molecules of unpleasant aroma come out. A similar problem may not be noticeable to others if they do not get close.
Some people have a lower olfactory threshold. They smell better than others, so sometimes they encounter misunderstandings from others. Some aroma may be too weak to be detected by anyone else. And this feature should also be taken into account by the doctor.
A separate group of causes are those that are associated with damage to any of the sections of the olfactory analyzer. The emerging odors do not reach others, since their formation, transmission and analysis in a particular person are disrupted. And although the basis for an unpleasant aroma may be some other (quite real) one, the final result is present only in the patient’s mind and poses a problem specifically for him.
There are quite a lot of conditions manifested by impaired sense of smell (dysosmia or parosmia). They include both respiratory pathology with inflammation of the nasal mucosa, for example, rhinitis or ARVI, and other disorders in the body:
- Hormonal changes (during pregnancy, during menstruation or menopause).
- Bad habits (smoking, alcohol abuse, drugs).
- Taking certain medications and chemical poisoning.
- Endocrine disorders (hypothyroidism, diabetes mellitus).
- Systemic diseases (scleroderma).
- Traumatic brain injuries.
- Brain tumors.
- Neuroses or depression.
- Psychosis (schizophrenia).
- Epilepsy.
It is also necessary to remember about the so-called phantom odors, which are associated with some kind of stress in the past and left a strong impression. In similar situations they can come to the surface. As you can see, the source of the unpleasant odor can be hidden among a large number of diseases. And some can be quite serious. But you shouldn’t immediately get scared and look for a dangerous pathology - the causes of the disorders will become clear only after a thorough examination.
Why people imagine certain smells is a rather serious question and requires further research.
Symptoms
Any pathology has certain signs. To identify them, the doctor evaluates the patient's complaints, analyzes the factors that precede the appearance of an unpleasant odor, and conducts a physical examination. You should understand when a foreign odor is felt, whether it is constantly present or occurs periodically, how intense it is, what contributes to its disappearance, and what additional symptoms are present in the clinical picture. Sometimes this alone makes it possible to establish the cause of dysosmia, but not always.
The aroma that haunts the patient may have different colors. Those who drink citrus tea often feel a foreign burning smell, and hot spices can cause a feeling of the presence of sulfur in them. Simultaneously with the distortion of smell, taste also changes, since they are closely related. A bad runny nose, for example, can create the illusion that onions have become sweet and smell like apples.
ENT pathology
The first thing you should think about when complaining of an unpleasant odor is diseases of the ENT organs. When the nasal mucosa is damaged, the sense of smell is invariably impaired, but the patient may not always feel the smell of pus or rot. Most often, a similar symptom occurs with sinusitis, chronic tonsillitis or ozena. In the latter case, the smell is so pronounced that others notice it. But besides this, you need to pay attention to other symptoms:
- Impaired nasal breathing.
- Nasal discharge (mucopurulent or purulent).
- Heaviness in the projection of the paranasal sinuses.
- Dry mucous membranes and crusting.
- Sore throat when swallowing.
- Traffic jams on the tonsils.
If we are talking about acute sinusitis, then the purulent process in the sinuses invariably entails an increase in temperature and intoxication with headaches, but chronic sinusitis gives less pronounced symptoms. With tonsillitis, disorders of the kidneys, heart, and joints are often detected (the result of sensitization to streptococcal antigens). If the sense of smell is impaired due to ARVI, then in the clinical picture, in addition to a runny nose, against the background of intoxication there will be other catarrhal symptoms, for example, redness of the throat and lacrimation.
Pathology of the nose, paranasal sinuses and pharynx is the main cause of the appearance of a foreign odor, which can be perceived by others only upon close contact with the patient.
Digestive tract diseases
An unpleasant odor can also haunt those who suffer from diseases of the gastrointestinal tract. Impaired digestion of food is the main mechanism of this symptom. The smell of rotten eggs is disturbing in hypoacid gastritis (with reduced acidity) or duodenal ulcer; it does not appear constantly, but after eating. The clinical picture also contains other signs of dyspeptic syndrome:
- Belching.
- Nausea.
- Bloating.
- Changing the stool.
Many people feel discomfort in the stomach or pain in the epigastrium. And concomitant gastroesophageal reflux causes heartburn and further esophagitis. If the gallbladder is affected, then an additional symptom will be a feeling of bitterness in the mouth.
Psychoneurological problems
Many patients with neuropsychiatric status disorders perceive an odor that is not really there. It can have either a real prototype (illusion) or be based on non-existent connections (hallucination). The first situation can also arise in a healthy person who has suffered severe emotional stress, but it often becomes a constant companion for those who suffer from neurosis or depression. Additional symptoms of the pathology are:
- Decreased mood.
- Emotional lability.
- Irritability and anxiety.
- Feeling of a “lump” in the throat.
- Sleep disorders.
Characteristic signs will also be somatic functional disorders that arise due to an imbalance of nervous regulation (increased heart rate, increased sweating, nausea, shortness of breath, etc.). Unlike neurotic reactions, psychoses are accompanied by profound changes in the personal sphere. Then there are various hallucinations (auditory, visual, olfactory), overvalued and delusional ideas, when the perception of the surrounding world and behavior are disrupted, and there is no critical understanding of what is happening.
The feeling that you suddenly began to smell like rotten meat can occur with epilepsy. Olfactory and gustatory hallucinations are a kind of “aura” that precedes a convulsive attack. This indicates the location of the focus of pathological activity in the temporal lobe cortex. After a few seconds or minutes, the patient develops a typical attack with clonic-tonic convulsions, short-term loss of consciousness, and tongue biting. A similar picture also occurs with a brain tumor of the corresponding localization or skull injuries.
Neuropsychic disorders, as a cause of foreign odor, are perhaps the most serious situation that cannot be ignored.
Additional diagnostics
Smells that others cannot smell are a reason for a detailed examination. It is possible to find out the cause of what is happening only on the basis of a comprehensive diagnosis using a laboratory and instrumental complex. Based on the doctor’s assumption based on the clinical picture, the patient is recommended to undergo additional procedures:
- General blood and urine analysis.
- Blood biochemistry (inflammatory markers, liver tests, electrolytes, glucose, hormonal spectrum).
- Nasal and throat swab (cytology, culture, PCR).
- Rhinoscopy.
- X-ray of the paranasal sinuses.
- Computed tomography of the head.
- Echoencephalography.
- Fibrogastroscopy.
- Ultrasound of the abdominal organs.
To obtain maximum diagnostic value, the examination program is developed on an individual basis. If necessary, the patient consults not only an ENT doctor, but also other specialists: gastroenterologist, neurologist, endocrinologist, psychotherapist. And the results obtained make it possible to establish the final cause of the violations and eliminate the unpleasant odor that seemed to patients.
I. P. Pavlov believed that the problem of smell and odor is one of the most difficult in physiology and general biology. A person perceives smells through the nose. It is capable of perceiving and recognizing 4,000 different odors, and a very sensitive nose - up to 10,000, and special signals are transmitted to the brain about each individual smell. The olfactory nerves are almost never wrong. They won't transmit a lily signal when the air smells like a rose. Animals distinguish odors even better than people. Cats, dogs and horses have a developed sense of smell so strongly that, with a fair wind, they can distinguish the smell of a person they know from an entire block away. In wild animals, the sense of smell is developed and even stronger. The numerical magnitude of the nose's sensitivity to odorants is simply incredible. For example, an ordinary person smells vanillin at a concentration of 1 gram in 10 million cubic meters of air.
Aromas from the air enter the nasal cavity to the olfactory cells (about 30 million neurons). There are receptors on the surface of these ciliated cells. An impulse in the cell occurs when 8-10 molecules of an aromatic substance hit the receptors of the cilia. The sensation of smell occurs if at least 40 neurons are simultaneously excited. Even to perform such a seemingly simple task: how we distinguish smell, more than 6 million neurons are involved, each of which receives perhaps 10,000 contacts from its comrades. The odor signal travels through special cells directly to the hypothalamus of the brain. This is very important because this tiny organ regulates dozens of body functions such as temperature, thirst, hunger, blood sugar, sleep, sexual arousal and emotions such as anger and joy. At the same time, the odor signal is sent to an area called the Hippocampus, the part of the brain responsible for memory and attention. For this reason, smells are the most evocative of our memories. The world of smells surrounds us everywhere and continuously. Dozens of irritants penetrate the human nasal cavity every minute. However, we distinguish only some of them consciously. Most reactions to surrounding odors are subconscious.
Humans perceive only five basic odors.- mint, camphor, floral, ethereal, musky. All others are obtained by mixing the main ones.
Conscious reactions to smell- this is when the brain processes a numerous stream of information signals (highlighting the most vital), sends a return signal to which a person reacts (the smell of food or gas).
The mystery of the smell has not been completely solved, since scientists have not paid enough attention to it. One of the most interesting features of smell is the ability of this non-directional sensation to evoke a directional response. Animals with a pair of ears can determine the direction of sound very accurately. Even with the help of one ear, the animal can determine which side the sound is louder. Hearing is directional, like vision, but smell, like the sense of taste, has no direction.
There were more than 3 theories of smell. The greatest debate was caused by the question of whether the aroma molecule should come into contact with the receptors, or whether it emits waves that irritate the receptors.
Eymur's (key-lock) theory explains the smell as follows:“If the molecule is round, then the corresponding nerve receptor has a concavity into which the molecule fits.” However, Boston University neuroscientist John Cowhera discovered that this theory was flawed. In an experiment using a tomograph, Cauer discovered that three closely related chemicals - acetic acid esters, propyl acetate and amyl acetate, whose molecules have a similar shape, cause different activity in brain cells.
Recently, a young British biophysicist, Luca Turne, put forward a completely different concept of the mechanism of odor perception. According to this concept, smell, like color or sound, is determined by the frequency of vibrations, and the olfactory organ is like a device that is capable of recording these frequencies. Turn proved that different substances with different frequencies of interatomic vibrations have a similar odor. For the experiment, hydrogen sulfide and boron water were taken with an oscillation frequency of 2500 Hz. It turned out that boletus also smells of hydrogen sulfide, despite the fact that their molecules have different shapes.
American microbiologist Linda Buck may write a new page in the theory of smells. She managed to identify the gene in the human chromosome set that is responsible for olfactory receptors.
Let's discuss it together. Why does the poet connect the words “I live” with human senses?
Answer. Human life is an interaction with the environment, a constant exchange of substances with it. To live, a person needs to navigate the environment. And he does this with the help of his senses - vision, smell, hearing, touch, taste and others. Therefore, the poet described his feelings this way.
Vision
Question. Let's look at various items. What visual impressions did we get of them? What signs of objects did we see? Do we agree with the conclusion “The eyes are our “windows” to the world?”
Answer. I agree with this expression. We receive most of the information from the outside world through the organs of vision. We can determine the color of an object, its size, distance to it, and give a description. With the help of our visual organs, we recognize objects, distinguish people, and perceive written speech.
Hearing
Let's play. Let's close our eyes and try to determine from which side (left, right, back, front, etc.) the sound is coming. Do we agree with the conclusion: “Hearing helps us navigate the world around us?”
Answer. I agree with this statement. Thanks to sounds, we navigate the environment, we can communicate with each other, we hear the sounds of nature, music, and we avoid danger.
Question. Explain why these rules need to be followed.
1. Try not to shout, go away from places where there is a lot of noise and sharp sounds.
2. Do not turn on the tape recorder, radio, or TV at high volume.
3. Do not put objects into your ear.
4. Use a cotton swab to clean your ears.
Answer. These are all rules of hearing hygiene. Loud speech and music cause damage to the eardrum and auditory ossicles. At the same time, the nerve endings become tired, which leads to a decrease in the hearing threshold. If you insert various objects into the ear, you can damage the inner ear; the eardrum must be cleaned of earwax, but this must be done with soft objects.
Smell
Question. What is the sense of smell? What rules must be followed to preserve your sense of smell?
Answer. The sense of smell is the ability to perceive odors. There are a lot of smells. They can be recognized by special cells located in the nasal mucosa. We distinguish up to four thousand odors, but a dog is several times more. From sensory cells, information enters the brain, where it is analyzed.
Exercise. Let's smell various substances: perfume, garlic, horseradish, flower. Let's divide odors into two groups - pleasant and unpleasant.
Answer. Pleasant smells - perfume, flowers; unpleasant odors – garlic, horseradish.
Let's discuss it together. Let's smell something pleasant, like tasty food. To do this, take a deep breath through your nose. Now let’s hold our nose and take a deep breath through our mouth. In what case will we smell? Which sense organs “tell” us that the food we eat is not spoiled? Let's explain our answers.
Answer. We smell when we breathe through our nose. It is the olfactory organs that first of all tell us that food is not spoiled. Secondly, these will be the taste organs.
Question. Prepare for the conversation. Think about how to answer the questions: “Why do we almost stop smelling when we have a runny nose? Why does a person never confuse the smell of fish and the smell of flowers?”
If you have a cat or dog at home, observe how they react to smells. Talk about it in class.
Answer. During a runny nose, the nerve endings in the nasal mucosa become clogged. When a cat and a dog sniff something, their nostrils widen, they inhale deeply, their breathing quickens.
Taste
Exercise. Place a piece of sugar on your tongue. Let's wait until it melts. Wipe your tongue with a clean napkin and quickly run another piece of sugar over it. In what case did we feel the taste? Let’s analyze whether we can draw the following conclusion: “Saliva helps to distinguish taste. A dry tongue cannot sense taste.”
Answer. Yes, we can draw such a conclusion. The sensitive endings on the tongue are irritated only when the food is wet. And saliva wets food.
Question. Look at the drawing. Read the signatures. Using the words “left”, “right”, “front”, “back”, explain how different parts of the tongue (taste zones) distinguish between sour, sweet, salty, and bitter tastes.
Explain how you understand the word “taster”. What sense organs do you think are especially developed in people of this profession?
Answer. The back of the tongue detects bitter taste. The left and right sides of the tongue distinguish between sour tastes. The left and right parts closer to the tip of the tongue distinguish between the salty taste. The tip "in front" of the tongue detects sweet taste. A taster is a person who is better able than others to identify different tastes and smells. These people have better developed senses of smell and taste than others.
Touch
1. Take a piece of ice in your hands, touch a glass of hot water, and stroke the fur with your palm. What do we feel (touch)? Let’s draw a conclusion by answering the question: “Does the sense of touch help us perceive the world?
2. Place your hand in warm water. What we feel. Will the feeling change after a few minutes? Let’s analyze whether we can draw the following conclusion: “The hand got used to the temperature and stopped feeling the heat.”
3. Let’s conduct a game-exercise “identify an object by touch.” The student puts his hand into the bag, selects an object without looking and determines by touch what it is and what it is made of.
Let's compare our conclusions with the text.
Answer. 1. With the help of the organs of touch, we perceive the world around us - heat, cold, the surface of objects - soft, hard, smooth, rough. From tactile cells, signals go to the brain and a person, even with his eyes closed, is able to distinguish the size and shape of an object, react to changes in temperature, and withdraw his hand from a hot object or a piercing object.
2. First we feel warmth, and then the brain stops responding to incoming signals. This is a protective reaction of the brain. This is how he protects himself from fatigue. But in everyday life they say that the hand has gotten used to it.
3. A person identifies objects by touch. The experience of a previous life helps with this. But if an unfamiliar object comes across, the person will find it difficult to name what it is.