A person with an outstanding sense of smell. Human olfactory organ

The five senses allow us to know the world around us and respond in the most appropriate way. The eyes are responsible for vision, the ears are for hearing, the nose is for smell, the tongue is for taste, and the skin is for touch. Thanks to them, we receive information about our environment, which is analyzed and interpreted by the brain. Our reaction is usually to prolong pleasant sensations or to stop unpleasant ones.

Vision

Of all the senses available to us, we most often use vision. We can see thanks to many organs: light rays pass through the pupil (hole), the cornea (a transparent membrane), then through the lens (a lens-like organ), and then on to the retina ( thin membrane V eyeball) an inverted image appears. The image is converted into a nerve signal thanks to the receptors lining the retina - rods and cones, and is transmitted to the brain through optic nerve. The brain recognizes the nerve impulse as an image, turns it in the right direction and perceives it in three dimensions.

Hearing

According to scientists, hearing- the second most used sense by a person. Sounds (air vibrations) through ear canal penetrate to eardrum and make it vibrate. They then pass through the fenestra vestibule, an opening covered by a thin film, and the cochlea, a fluid-filled tube, irritating the auditory cells. These cells convert the vibrations into nerve signals that are sent to the brain. The brain recognizes these signals as sounds, determining their volume level and pitch.

Touch

Millions of receptors located on the surface of the skin and in its tissues recognize touch, pressure or pain, then send appropriate signals to the spinal cord and brain. The brain analyzes and deciphers these signals, translating them into sensations - pleasant, neutral or unpleasant.

Smell

We are able to distinguish up to ten thousand odors, some of which (poisonous gases, smoke) notify us of imminent danger. Cells located in the nasal cavity detect molecules that are the source of odor, then send the corresponding nerve impulses into the brain. The brain recognizes these odors, which can be pleasant or, on the contrary, unpleasant. Scientists have identified seven main odors: aromatic (camphor), ethereal, fragrant (floral), ambrosial (the smell of musk - an animal substance used in perfumery), repulsive (putrefactive), garlic (sulfur) and, finally, the smell of burnt. The sense of smell is often called the sense of memory: indeed, a smell can remind you of a very long ago event.

Taste

Less developed than the sense of smell, the sense of taste informs about the quality and taste of the food and liquids consumed. Taste cells located on taste buds, small tubercles on the tongue, detect flavors and transmit corresponding nerve impulses to the brain. The brain analyzes and identifies the nature of taste.

How do we taste food?

The sense of taste is not enough to evaluate food, and the sense of smell also plays a very important role. important role. The nasal cavity contains two odor-sensitive olfactory areas. When we eat, the smell of food reaches these areas that "determine" delicious food or not.

Perhaps everyone has noticed that women are able to detect subtle odors of perfumes and seasonings in dishes; they sometimes easily recognize flowers by their smell without even seeing them. There are women who use their sense of smell to determine that a downpour will soon begin. But men do not have this ability. What's the secret?

The sense of smell is the oldest human sense. Previously, it controlled 90% of human life, just like in animals. Nowadays, a person receives 2% of information through smell, while through vision - 90%, through hearing - 5%. But these two percent play a very important role.

The human olfactory system has a rather complex structure. IN upper section The nasal cavity contains an area with olfactory receptors that perceive odor and convert it into a nerve impulse sent to the brain. The center of smell in the brain is connected with the centers of other senses and, thanks to them, working together, smell is an essential addition to the basic information received from other analyzers: visual, auditory, gustatory, tactile. Those 2% of information received through the sense of smell can play a decisive role: in front of you there may be a person pleasant in all respects, but if you don’t like his smell, then all communication with him will come to naught, and even all his virtues will be seen by you as shortcomings.

A person can distinguish about 10,000 different odors, and a dog's nose can distinguish about half a million. The sensitivity of the nose is amazing. According to the acuity of smell, all living beings are divided into 3 groups:

1. anosmatics (they do not smell at all; dolphins are an example);
2. macrosmatics (they have an excellent sense of smell; these include predators and rodents);
3. microsmatics (their ability to perceive odors is below average). The person belongs to the third group.

The ability to capture odors depends on many factors. The first is the amount of olfactory epithelium in the nose (the number of olfactory receptors). In humans, this figure is 10 million, and it is the same for both men and women. For comparison, dogs have over 200 million olfactory receptors! Therefore, it is not in vain that they say that everything that smells can be found with the help of dogs. Secondly, the number of nerve cells in the olfactory bulb (bulb of touch) - the primary link of the center of smell - is of no small importance. Primary information processing occurs in the onion. And this is where the differences in the olfactory ability of different genders. Women have more neurons in the olfactory center than men. Researchers from the Federal University of Rio de Janeiro (Brazil) determined the absolute number of cells in the olfactory bulbs, and then the number of neurons. The study found that women have 43% more cells in their olfactory bulbs than men. When counting neurons, the difference reached 50%. The scientists do not claim that their work is clear evidence that the number of cells determines the superiority of the olfactory ability in women. However, according to study leader Roberto Lenta, it seems logical to assume that larger number neurons in the olfactory bulb correspond to more high sensitivity to smells. In addition, the researchers made another observation: Since the number of brain cells increases only slightly throughout life, women are apparently already born with them. Plus, women have more associative connections in their brains connecting different brain centers, so they quickly recognize odors, unlike men, who take longer to do so.

Even if a person receives relatively little information through the sense of smell, its importance is difficult to overestimate. With the help of smell, we unconsciously identify people who are pleasant to us. Thanks to the influence of smell, we recover faster and feel better (just remember aromatherapy). We learn to decipher smells and control them (perfumes), while forgetting that it is the smell that controls us. It is not without reason that they say that losing the ability to perceive smells means losing something very necessary, something as important as the taste of life.

The role of smell in life modern man cannot be underestimated. Surprisingly, the sense of smell allows us to smell more than 10,000 different smells. Most odorous substances can increase a person's appetite or stimulate good mood, and also promote the activation of brain activity.

The nose is so sensitive that some marketers use it in business. For example, how many times have you made a successful or not so successful purchase under the influence of a charming aroma in a store?

The sense of smell allows a person to avoid the dangers that exist around him, and also stimulates pleasure from objects and people nearby. But for some reason we underestimate the role of smell in our lives. In most cases, the human nose is an organ whose existence is remembered only when it is affected by various infectious or inflammatory processes.

The sense of smell is extremely highly developed in humans from birth. For example, a newborn may not see or hear his mother, but by smell he is able to recognize her from hundreds and even thousands of other women. Unfortunately, main body sense of smell - the nose, begins to lose its sensitivity already in the second year of a little person’s life.

As each year of life progresses, the sense of smell decreases, and the sensory receptors atrophy one by one. This is an irreversible process that no one can help influence. Thus, upon reaching old age, a person may notice that he no longer hears the smells around him so clearly. And this is absolutely normal occurrence, which can only be corrected by strong drug therapy.

A person’s sense of smell can decrease not only as a result of age-related changes. The nose may become less sensitive as a result of:

• Inflammatory processes occurring in the nasopharynx;
• Formation of nasal polyps;
• Allergic reaction;
• Side effects after taking drugs that eliminate cardiovascular failure;
• Poor oral hygiene;
• Impact toxic substances on the body;
• Consequences of acute viral hepatitis;
• Deficiency of vitamins and minerals;
• Bad habits.

The organ of smell loses its functionality as a result of cirrhosis of the liver, damage to the body by multiple sclerosis, and the formation of benign or malignant tumors.

The sensitivity of odor receptors decreases in people diagnosed with Alzheimer's disease, pathological condition Parkinson's, epilepsy, and those who have suffered traumatic brain injury or suffer from dysfunction thyroid gland. Only a specialist can determine and understand which of the above reasons affected the organ of smell.

Ability to hear smells and personal relationships

The human sense of smell is a means of perceiving and receiving information that works 24 hours a day. Few people know that the sense of smell is very closely related to the sense of taste of food. For most famous chefs, the loss of smell can be equated to death.

Surprisingly, a person uses his nose not only to breathe, but also as a kind of x-ray of the people around him. Many people think that love for friends and life partner begins in the heart, but this is not so.

The first instinct that is triggered in a person is to scan the smell of an approaching person. And if odorous substances, which the human body highlights, we like, then this is already the first step towards rapprochement. This is very easy to check for yourself. Is there someone around you whose smell you don’t like?

How ideas about smell are formed

Smell and smell are two components that work so that a person can live a full and vibrant life. The olfactory system consists of the following components:

• Olfactory stimuli;
• Olfactory threads;
• Mucous membrane;
• Bulb;
• Olfactory tract;
• Cerebral cortex.

The sense of smell enters the brain through olfactory analyzer, that is, the nose. It contains the receptor for the olfactory epithelium and the olfactory nerve.

The ability to perceive and analyze surrounding odors is carried out through receptor cells, of which there are about 10 million in humans. How can a person distinguish the odorous substances that surround him? The aroma enters the nose, affecting sensitive receptors, which, in turn, transmit a corresponding signal to the cerebral cortex.

Perception of smells around us

The role of the sense of smell is manifested not only in the perception of surrounding odors, but also affects color perception, excitability vestibular apparatus, hearing and taste. If the nose does not function as a result inflammatory processes, then a person’s thinking slows down sharply. The sense of smell takes active participation and in the formation of behavioral reactions, emotionality and memory. All substances that enter the body through the nose find a response in the form of its reaction.

So, ammonia, possessing caustic and pungent odor, provokes irritation trigeminal nerve, activates brain activity and brings the person to consciousness. Thanks to the action of odorous substances, it is possible to successfully control a person’s emotions and feelings, which is what successful companies use in their practice. Next time you buy fast food, think about it: are you really hungry or just can't resist the smell of it?

Despite the fact that a person’s sense of smell contributes to the perception of the surrounding world and assessment of the surrounding environment, the threshold of sensitivity differs for each person. So, someone’s nose may react to the smell of vanillin, which comes from a neighboring street, but someone else will not hear it even at a distance of a couple of centimeters.

It is interesting to know that the threshold for the perception of odors can increase or decrease depending on the time of day and season. As a rule, the nose becomes more sensitive after prolonged sleep, as well as during periods of increased hunger.

Even if a person has a good sense of smell, he is still not able to sense and fully experience his own smell. Physiology is designed in such a way that we are able to perceive the odors of the people around us, but the odorous substances of our body are blocked when they hit the sensitive receptors of the epithelium.

Therefore, it is so important to pay attention to your own hygiene and monitor the amount of sweating. Surprisingly, we can get used to our own bad smell, as a result of which our sense of smell sharply decreases. TO basic rules and advice on maintaining good hygiene includes taking a daily shower, preferring clothing made from natural materials, and using deodorants.

If a person smells bad, then gradually this smell begins to spread to the room in which he lives. So creating a pleasant aroma in your own home is a prevention against a decrease in the sense of smell.

Development of the sense of smell

Experts advise constantly developing your sensitive receptors. To do this, you need to try to surround yourself with pleasant smells. Smell training can be done by visiting perfume shops, bakeries and specialty departments that sell herbs and spices. The house where you live can be decorated with various pillows of dried herbs that emit a pleasant aroma.

If you have reduced olfactory function, then increase perception taste qualities dishes can be added to them by adding aromatic herbs and seasonings. It is known that sensitivity to odors is directly proportional to appetite.

If a person does not feel the aroma of food, then his appetite does not awaken. To stimulate the taste and olfactory receptors, you can place a saucer with coffee beans in the kitchen. This aromatherapy will help improve mood, eliminate depression and stimulate nasal receptors.

May 13, 2009

The sense of smell gives us the opportunity to enjoy pleasant smells, and sometimes it can save our lives: prevent us from drinking vinegar instead of vodka, tell us that we shouldn’t eat a pie with rotten meat, or remind us that we shouldn’t flip the switch if we smell gas. However, the smells around us have properties that many may not even suspect.

Something like the human sense of smell exists even in microorganisms: chemotaxis - the ability to move towards food sources and away from hazardous substances– exhibited by all motile unicellular organisms. But let's skip the roughly 3.5 billion years of evolution of smell and go straight to mammals and humans.

For many animals, the sense of smell is at least as important important source information than sight and hearing: any dog ​​lover knows that dogs get lost when they meet a drunk owner: he looks and talks the same, but smells completely different! And not from the “exhaust” (the smell of paint, herring, etc. does not have such an effect), but because, together with the rest of the biochemistry, alcohol changes the composition of sweat and, accordingly, imperceptible to human nose shades of individual scent.

For you and me, the ability to feel and distinguish odors, at first glance, is not so important. Sometimes it even gets in the way: everyone can remember situations when he was ready to give half his kingdom in order not to smell the smell of a homeless person entering a trolleybus or a colleague who had eaten garlic. And although without the pleasure of smelling flowers, perfume, food and many other aromas, the world would lose a lot, for humans, smell is in fourth place among the five senses. Through vision, we receive at least 90% of information about the world around us, and without it, a person uses tactile sensations and hearing to navigate in space and recognize living and inanimate objects.

Scientists have deciphered the basic mechanisms of the sense of smell quite recently. This lag is due not only to an underestimation of the importance of its role in human life, but also to the extreme complexity of the olfactory receptors.

What are we smelling?

Gordon Shepherd, professor of neurology at Yale University, author of the three-volume Neurobiology, which has gone through several reprints, and an incomparable expert on the mechanisms of impulse transmission by synapses of dendritic spines of the olfactory bulb (he has one like this) narrow specialization), began the answer to this question like this: “It seems to us that we smell with the help of our nose, but this is the same as saying that we hear with our earlobes.” The nose itself is necessary in order to direct air containing aromatic molecules to the olfactory epithelium - symmetrical areas of the mucous membrane located deep in the nasal cavity, slightly below eye level.

We feel odors only during inhalation, since the exhaled air passes only through the lower nasal turbinates and does not come into contact with the respiratory epithelium. When you inhale calmly, only 7-10% of the inhaled air passes near the olfactory epithelium located in the uppermost part of the nasal cavity, so to enhance the sensations you need to inhale as deeply as possible. You can also take an example from animals and “sniff”, taking frequent short breaths in close proximity to the object being studied, which allows you to maximize the concentration of odorous molecules near the olfactory receptors.

Due to the folds, shaped like ridges, the total area of ​​the olfactory epithelium in humans is 5-10 cm2. At this second milestone olfactory system There are, according to various sources, from 10 to 50 million cells that register odors. In animals their number is usually much greater. For example, the olfactory epithelium in shepherd dogs contains up to 220 million receptor cells.

The olfactory receptor is a sensory nerve cell, from which two processes extend. To the nasal cavity there is a short dendrite (a sensitive process of a neuron) with at least 10 cilia, the tips of which are located on the very surface of the olfactory epithelium and protrude into the mucus covering it. To the brain - a longer motor (transmitting) process, an axon, intertwined with the axons of other olfactory neurons in a filament olfactory nerve, passing through the openings of the ethmoid bone of the skull into the olfactory bulb - a brain structure that carries out primary processing information about odors. The olfactory bulb is larger, the more acute the animal’s sense of smell, so in bloodhound dogs it is much larger than in the much larger human brain.

From the olfactory bulb, nerve impulses enter the primary and then the higher olfactory areas of the cerebral cortex, forming a conscious sensation of the nature and intensity of the smell. The final processing point for odor data is the limbic system, which regulates the body's emotional and behavioral responses.

How does this work?

Molecules of aromatic substances entering the air current nasal cavity, dissolve in the mucus covering the olfactory epithelium and interact with receptor proteins contained in the membrane of the cilia of olfactory neurons. This interaction changes the ionic permeability of the cell membrane and forms an electrical impulse transmitted along the cell axon to the olfactory nerve and further, up to motor neurons spinal cord, giving the muscles commands to pinch your nose with your fingers and move away - or vice versa.

WITH central mechanisms The olfactory system was understood by specialists who studied it quite a long time ago, but the protein receptors, undoubtedly present on the membranes of the dendrites of the neurons of the olfactory epithelium, remained elusive for many years. This riddle was solved only in 1991 by Columbia University scientists Linda Buck and Richard Excel. In 2004, the discovery brought them Nobel Prize in physiology and medicine.

The traditional approach to studying the mechanisms of operation of olfactory receptors was to measure the activity of certain neurons in response to various stimuli. To do this, electrodes were connected to the animals' olfactory nerves and they were allowed to inhale various substances. As a result, it was only possible to find out that the same neuron can respond to different substances, but the mechanisms underlying this process for a long time remained unclear.

Buck and Excel were chosen on principle new approach– they turned to rapidly developing genetics and began a search for genes whose activity is recorded exclusively in the olfactory epithelium. At first, their experiments were also unsuccessful, which Excel later explained by the existence huge amount receptor proteins, the response of each of which to a specific odor is too weak to be detected by existing methods.

The scheme invented by Buck helped scientists cope with this problem, which, using three assumptions, significantly reduced the search area. According to the first assumption, based on the scattered data available at that time scientific facts, it was necessary to look only for the genes of proteins that have a certain similarity to rhodopsin - a receptor protein due to which the formation of an electrical impulse occurs in the rods of the retina, cells that do not distinguish colors, but react to changes in illumination and provide twilight vision. In addition, the required proteins had to belong to the same family, and the genes encoding them had to be active exclusively in the cells of the olfactory epithelium.

In rats, there were about a thousand genes that met all three criteria - approximately 1% of the entire genome. One in every 100 rat genes is involved in smell recognition, indicating the extreme importance of the olfactory system for rodents, close relatives of primates: our branches on the evolutionary tree diverged about 25 million years ago. A search in DNA libraries made it possible to find analogue genes associated with the primary perception of odors in the genomes of other species (mice, salamanders, catfish, dogs, humans and other animals). True, unlike most animals, in which most of these genes regularly synthesize the corresponding proteins, in different types In apes, 28-36% of the olfactory receptor protein genes are inactive, and in humans - almost 60%. Apparently, mutations that block the activity of olfactory receptor genes began to accumulate from the time when acute sense of smell lost its importance for the survival of human ape-like ancestors.

Further study of the olfactory system showed that each individual receptor neuron can recognize many odorant molecules, each of which activates different protein receptors on the surface of its membrane. This combinatorial signal coding system makes it possible to recognize an almost unlimited number of aromas.

Even slightly different in chemical structure the molecules activate different combinations of receptor proteins located on the membranes of different neurons, so the smell of octane alcohol resembles the smell of citrus fruits, and octanoic acid, which differs from it only by one additional oxygen atom, resembles the smell of sweat.

A change in the spatial structure of molecules can lead to the same effect. For example, the odors of cumin and spearmint (it differs from the more famous peppermint in the absence of a cooling sensation and a less pungent odor) are provided by d-carvone and l-carvone - chiral (from the ancient Greek χειρ - “hand”) isomers, molecules with the same chemical composition, different from each other, like an object from its mirror image.

Besides, more molecules activates more wide range receptors, which is why the same substance can smell differently depending on the concentration.

The most surprising example is skatole, a heterocyclic compound formed during the decomposition of protein compounds and giving a specific odor to feces. At the same time, in low concentrations skatole has pleasant smell and is included in perfumery products and food essences.

The most versatile in this regard are aldehydes. So, coconut aldehyde in small concentration it smells not like coconut, but like apricot or peach, and the smell of anise aldehyde when diluted smells like the aroma of fresh hay, rose hips and hawthorn flowers.

The most unpleasant-smelling compounds include sulfur-containing substances, starting with the simplest - hydrogen sulfide H 2 S. Mercaptans are considered the “champions” among them. Their mixture provides a skunk-like stench that can make a person faint. Mercaptans give a unique aroma to rotten cabbage and domestic gas: natural gas It does not smell of anything, and for safety reasons a little bit of isoamyl mercaptan is added to it. Sulfur-containing compounds diallyl disulfide (CH 2 =CH–CH 2) 2 S 2 and allicin CH 2 =CH–CH 2 –SO–S–CH 2 –CH=CH 2 provide pungent odor garlic, and the main component of the smell of onions is allylpropyl disulfide CH 2 =CH–CH 2 –S–S–CH 2 –CH–CH 3. Garlic and onions themselves (belonging to the genus Allium) do not contain allyls: when cut under the action of enzymes, numerous molecules of the amino acid cysteine ​​containing sulfhydryl groups –SH are converted into them. The peculiarity of these disulfides is that the odor is almost impossible to get rid of either by brushing your teeth or rinsing your mouth. The fact is that these compounds, having penetrated the intestinal walls into the blood, are carried throughout the body, including into the lungs, from where they are released with exhaled air.

Smell in our lives

The sense of smell is most important in the first minutes of a person’s life, since only thanks to it does the baby recognize its mother and find a breast that smells of milk. In the next couple of months, until the child’s vision becomes sufficiently sharp, he perceives the world around him mainly through smells. As we grow older and develop other senses, the sense of smell loses its importance. At the same time, atrophy (death) of the olfactory nerve fibers occurs. During the first year of life, the acuity of a person’s sense of smell decreases by 40-50%, and the further speed and degree of deterioration in the ability to recognize odors depends on individual characteristics body, gender, lifestyle and exposure various factors environment. For example, in novice smokers, the ability to distinguish odors decreases by 50-60%, after which it is restored by 20-30%. When you quit smoking, hyperosmia develops - the acuity of smell increases by about 20% compared to the original.

It is believed that a person is more sensitive to unpleasant odors. We almost always perceive odors that signal danger as unpleasant: do not eat rotten meat or rotten fruits, stay away from hydrogen sulfide, chlorine, ammonia, do not get into excrement - they may contain worm eggs, dysentery amoebas and other cholera... Tech Natural selection eliminated our ancestors (who were still covered with scales, not fur), who did not have such associations. Although there are exceptions - for example, garlic, which fully falls under the popular proverb “it doesn’t smell like it” :)

However, the substances that we can smell in the smallest concentrations smell pleasant. Vanillin has long been considered the record holder: it can be smelled at a concentration of 2×10–11 g per liter of air. But more recently it turned out that one of the chiral isomers of a substance called wine lactone (it gives wines a sweetish-coconut aroma) is felt at a concentration two thousand times lower: one hundred trillionth (10–14) grams in 1 liter of air. And the smell of its mirror isomer (in the figure on the right) can only be felt at a concentration that is 11 orders of magnitude higher - 1 mg/l.

Women in general have a more acute sense of smell, which lasts longer old age. However, paradoxically, professions related to smell discrimination are exclusively male. The fact is that hormonal changes during monthly cycles female body, affect work various organs and systems, including the olfactory system. As a result, at the beginning of the cycle, women often develop temporary hyposmia - decreased sensitivity to odors. This is not observed when taking hormonal contraception, maintaining constant hormonal background in the body, but it is obvious that taking pills cannot be prerequisite hiring.

Without the sense of smell, our food would become almost tasteless. Human taste buds distinguish only four sensations: sweet, salty, sour and bitter, and the rest is a variety of tastes various dishes and drinks provide combinations of aromatic substances. At severe runny nose When the upper nasal turbinates are “clogged” and the air containing aromas simply does not reach them, everything seems tasteless and unappetizing. Experiments have shown that if a person with a pinched nose is also blindfolded in order to deprive him of visual associations with the foods he eats, he is unlikely to be able to distinguish an apple from a potato or red wine from coffee.

Smells can change performance various systems body. The most obvious example is the increased production of saliva and digestive juices from food odors. Sharp and unpleasant odors(for example, ammonia) increase blood pressure and speed up the heartbeat, while pleasant ones, on the contrary, reduce blood pressure, slow down the pulse and cause an increase in skin temperature, which relaxes and calms a person.

How valid are the statements of aromatherapists - for example, this: “the aromas of lavender, chamomile, lemon and sandalwood weaken brain activity faster than any depressant, and jasmine, rose, mint and clove stimulate cells gray matter more powerful than strong coffee"? Judging by the fact that in articles by different authors one can find directly opposite statements about the effect of odors on the psychophysiological state of a person, this action is explained not by the nature of the smell itself, but by a psychological attitude toward the expected effect.

Another, perhaps the most mysterious question in the science of smells is their role in the sexual behavior of Homo sapiens. We'll talk about this.

Evgenia Ryabtseva,
portal “Eternal Youth”

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, in the upper part of the nasal cavity, the so-called olfactory fissure, the olfactory region is located. 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: Central department - cortical olfactory center located on bottom surface temporal and frontal lobe cortex cerebral hemispheres. 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 are transmitted to the nuclei brain stem, and then into the area 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, harmful chemical compounds, water and various contaminants into the body. 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?