Analyzer olfactory: structure and function. Age features of the olfactory analyzer

With the help of analyzers of various types, people are oriented in the surrounding world. It is through sight, hearing, smell and other senses that we perceive the external environment, recognize the dangers. For each person, different analyzers can not be developed in the same way. We will try to understand in the article what the olfactory analyzer is. The structure and functions, the significance for the health of one of the senses are discussed in this article.

Definition of the sense of smell

Most of the information about the world around the person perceives with the help of the organ of vision, but without the sense of smell, the picture would not be so bright and understandable.

The olfactory system is designed to recognize substances that are capable of dissolving and have volatility. This system creates subjective images in the form of certain smells. The significance of the olfactory analyzer is also that it can provide an objective assessment of the quality of air, food and the environment as a whole.

If we compare the organ of smell in humans and animals, then we can say that for animals this organ has a special significance. But it can not be developed in the same way for everyone. For example, there are life forms in which the olfactory analyzer is developed quite well. So, some species of butterflies can find their partner by smell at a distance of up to 8 kilometers. Everyone knows dogs that can follow the trail of a man, guided by the smell of his things.

Functions of the olfactory organ

If we consider the functions of the olfactory analyzer, we can note the most important and significant:

1. Analysis of food for edibility and attractiveness. With the help of this system, the degree of suitability of the product can be determined.
2. Formation of food behavior.
3. The olfactory analyzer takes a direct part in setting up the digestive system for food processing.
4. Determination of dangerous substances for the human body.
5. Formation of sexual behavior, which can change under the influence of pheromones.
6. With the participation of this analyzer, the orientation of the person in the environment takes place.
7. The knowledge of the external world does not do without the sense of smell.

It can be noted that in people who are deprived of sight, the sense of smell can become aggravated, and they feel smells much better, which help them to orient themselves in this world.

Structure of olfactory analyzer

If we consider the structure of this sense organ, then the following departments can be noted:

1. Peripheral. It includes receptor cells located in the nasal mucosa. They end with cilia, surrounded by mucus. In it, odorous substances dissolve. There is a chemical interaction, which is transformed into a nerve impulse.
2. The conductor department consists of the olfactory nerve. On it signals from the receptors go to the forebrain, where the olfactory bulb is located. In it, the primary analysis of information occurs, then the impulses will go to the next section of the analyzer.
3. The central section is located in the temporal and frontal lobe of the cerebral cortex. It is here that the final investigation of the information is carried out, the smell is recognized and the final response of our organism to its effect is formed.

We will get acquainted with the structure and functioning of these departments in more detail.

Peripheral part of the analyzer

Considering the structure of the olfactory analyzer, it is necessary to begin with the initial department. It is located in the nasal cavity. In these places, the mucous membrane is slightly thickened, covered with mucous secretions, which play a protective role, protect against drying, and also participate in the removal of the remaining irritants after the end of their action.

It is here that contact between odorous substances and receptor cells is carried out. In the epithelium, two types of cells are distinguished:

• Supporting. They take part in metabolic processes.
• Olfactory. This is the receptors themselves, which have a large number of cilia to increase the area of contact.

Olfactory cells have two processes, one of which passes to the olfactory bulb, and the second has the shape of a rod and ends with a bubble with cilia.

Conducting department

This department is intended for carrying out information, therefore it is represented by nerve pathways that form the olfactory nerve. It consists of separate bundles that go to the visual hillock.

There is a connection with the limbic system, which explains the presence of emotions in the process of perception of odors. For example, some smells can cause pleasure, others - disgust and so on.

Central analyzer section

This department includes an olfactory bulb. This is also the department in the temporal lobes of the brain.

It is located in the anterior part of the pear-shaped cortex in the hippocampus region.

Mechanism of perception of odor

To effectively perceive irritating substances, their molecules must first dissolve into the mucus that surrounds the receptor cells. Then there is interaction with special proteins, built into the cell membrane.

Such contact is possible if the shape of the molecule of the stimulus corresponds to the shape of the protein. The mucosal substance controls the accessibility of the surface of the receptors for molecules of an odorous substance.

After the molecule of the stimulus comes into contact with the receptor protein, a change in the structure of the latter takes place, as a result of which the sodium ion channels open in the membrane. Sodium ions penetrate inside and create positive charges, which lead to depolarization of the membrane.

From the receptor cell, a mediator is released, which leads to the formation of a nerve impulse in the nerve fiber sections. Thus, in the form of nerve impulses, the olfactory excitation begins to be transmitted to other parts of the analyzer.

The work of the olfactory system

If we imagine how the olfactory analyzer works, then all the work can be divided into several stages:

1. Promotion of an odorous stimulus to receptor cells, which ends with a connection to the receptor proteins.
2. Transformation of the chemical effects of an odorous substance into a nerve impulse. This stage begins with the attachment of the stimulus to the receptor and ends with the generation of nerve impulses.
3. Movement of the nerve impulse to the lower nervous center. It can be deciphered as movement towards the olfactory bulb.
4. The transformation of the pulse in the olfactory bulb.
5. Promotion of nerve impulses to higher olfactory centers.
6. Construction of an image of irritation in the form of a certain smell.

All these stages consistently follow one another. If there are problems or violations on one of them, we can say that the perception of odors is violated.

Getting used to the olfactory analyzer

We analyzed the features of the human olfactory analyzer, but it should also be noted that this sensor system is able to adapt. This occurs with prolonged exposure to the stimulus.

Adaptation of the analyzer can occur within a few seconds, and sometimes it takes up to five minutes. It all depends on a number of factors:

• Duration of contact with odorous substance.
• Concentration of the stimulus.
• Air flow rates.

There is a fairly large group of odorous substances to which the olfactory analyzer adapts quickly. It takes very little time, and the smell ceases to be felt. A vivid example is the complete adaptation to the smell of your body, room, things.

To some irritants, habituation is formed slowly or in general only partially. Under the influence of a weak olfactory stimulus, for a short time, the addiction can appear as an increase in the sensitivity of this analyzer.

It has already been established that the development of adaptation does not occur in the first section of the analyzer, but in the latter, that is, the cortical one. Often, when the same fragrant substance lasts for a long time, a stable focus of excitation is formed in the cortex of the large hemispheres. In these situations, a sense of smell can also occur when exposed to other stimuli. Sometimes this feeling can become annoying and appears even in the absence of irritants. In this case, you can talk about hallucinations, or illusions.

It can only be said with certainty that if adaptation to one particular odor is observed, this will not affect the perception of other stimuli in any way, since all stimuli affect different receptors.

Theory of perception of odors

Currently, more than 10 thousand odorous substances are known. All of them can be grouped into seven classes of primary odors:

• Floral.
• Mint.
• Musky.
• Ethereal.
• Putrefactive.
• Camphoric.
• Corrosive.

If there is a mixture of several odors, then its olfactory analyzer can perceive as a completely new fragrance. Molecules of different substances differ in different forms, for example, camphor smell has round molecules, and musky - in the form of a disk. In addition, they differ also by the electric charge: some can have a positive, and others - a negative one.

There are many theories that try to explain the mechanism of perception of odors. At present, the most common is the stereochemical, which asserts that there are several types of sites on the membrane of the receptor cells. They differ in their structure and electrophilicity. They are able to recognize fragrant molecules of a certain shape and size.

Types of odor disorders

In addition to the fact that the olfactory analyzer is developed in all not the same way, besides it is possible to observe some violations and deviations in its work:

• Anosmia is a complete lack of the ability to perceive odors.
• Hyposmia is a reduction in smell.
• Hyperosmia, on the contrary, is observed with increased olfactory sensitivity.
• Parosmia characterizes inadequate perception of odors.
• Disturbance of differentiation.
• The appearance of olfactory hallucinations.
• Olfactory agnosia is put in the event that a person smells, but can not recognize it.

It should be noted that with age, a gradual decrease in olfactory sensitivity occurs. The olfactory analyzer is no longer able to detect smells so clearly and quickly. Scientists have calculated that by the age of 50, the sense of smell of an average person has been reduced by half compared to youth.

Olfactory analyzer and its age features

The very first during the intrauterine development of the olfactory analyzer begins to form the peripheral department. This is already at the 8th week of development. By the end of pregnancy, or rather, by the end of 8 months, this analyzer is already fully formed.

Already immediately after birth, one can observe the reaction of a newborn to smells. This manifests itself in the form of mimic movements, changes in the functioning of the heart muscle, the frequency of breathing, the position of the body.

It is with the help of the sense of smell that the baby recognizes the smell of his mother. This sense organ is an important component of the formation of food reflexes. Gradually, when the child grows up, there is an increase in the analyzer's ability to differentiate odors. The fineness and strength of this process increases by 4 months.

If we compare the ability to perceive and differentiate odors in children 5-6 years old and adults, then we can say that the latter is much higher.

These are the age features of the olfactory analyzer. You can also say that as a result of systematic training, you can significantly improve your sense of smell, but heavy smokers risk losing their perception, because the constituent components of tobacco smoke negatively affect the receptors. Also, frequent inflammatory diseases of the nasal cavity contribute to reducing the sense of smell.

So we examined the olfactory analyzer. The structure and functions of it are described with all possible accessibility. It can be said with certainty that all sense organs are important for a person. If there are problems in the work of at least one analyzer, then one can already say that the adequacy of perception of the surrounding world is reduced, the fullness of sensations from life disappears. Take care of yourself and your senses.