With the help of analyzers of various types, a person orients himself in the world around him. It is through sight, hearing, smell and other senses that we feel the external environment, recognize dangers. Each person's different analyzers may not be developed in the same way. We will try to figure out in the article what an olfactory analyzer is. The structure and functions, the significance for the he alth of one of the sense organs are discussed in this article.
Definition of the olfactory organ
Most of the information about the world around a person perceives with the help of the organ of vision, but without the sense of smell, the picture would not be so bright, understandable.
The olfactory system is designed to recognize substances that are soluble and volatile. This system creates subjective images in the form of certain smells. The value of the olfactory analyzer also lies in the fact that it is able to provide an objective assessment of the quality of air, food and the environment in general.
If we compare the olfactory organ in humans and animals, we can say that foranimals, this organ is of particular importance. But it may not be developed equally for everyone. For example, there are life forms in which the olfactory analyzer is well developed. 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 person, 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:
- Analysis of food for edibility and attractiveness. With this system, you can determine the degree of suitability of the product.
- Formation of eating behavior.
- The olfactory analyzer is directly involved in setting up the digestive system for food processing.
- Determination of substances hazardous to the human body.
- Formation of sexual behavior, which can change under the influence of pheromones.
- With the participation of this analyzer, a person is oriented in the environment.
- Knowledge of the outside world is not complete without the organ of smell.
It can be noted that in people who are blind, their sense of smell can be aggravated, and they are much better at smelling things that help them navigate the world.
Structure of the olfactory analyzer
If we consider the structure of this sense organ, we can note the following departments:
- Peripheral. It includes receptor cells located in the nasal mucosa. They end in cilia surrounded byslime. It dissolves odorous substances. A chemical interaction occurs, which is converted into a nerve impulse.
- The conduction department consists of the olfactory nerve. Through it, signals from receptors go to the forebrain, where the olfactory bulb is located. The primary analysis of information takes place in it, then the impulses will go to the next section of the analyzer.
- The central section is located in the temporal and frontal lobes of the cerebral cortex. It is here that the final study of information is carried out, the recognition of the smell is carried out and the final response of our body to its influence is formed.
Let's 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 start from the initial section. It is located in the nasal cavity. In these places, the mucous membrane is slightly thickened, covered with mucous secretions on top, which play a protective role, prevent drying out, and also participate in the removal of remaining irritants after their exposure has ended.
This is where the contact between odorous substances and receptor cells takes place. There are two types of cells in the epithelium:
- Support. They take part in metabolic processes.
- Olfactory. These are the receptors themselves, which have a large number of cilia to increase the contact area.
Olfactory cells have twoprocess, one of which extends to the olfactory bulbs, and the second has the shape of a stick and ends with a bubble with cilia.
Conductor department
This department is designed to carry information, therefore it is represented by the nerve pathways that form the olfactory nerve. It consists of separate bundles going to the thalamus.
A connection with the limbic system was noticed, which explains the presence of emotions in the process of smelling. For example, some smells can cause pleasure, others disgust, and so on.
Central Analyzer Section
This department includes the olfactory bulb. This also includes the department in the temporal lobes of the brain.
It's all located in the front of the piriformis lobe of the cortex in the hippocampus.
Smell mechanism
For effective perception of irritating substances, their molecules must first dissolve in the mucus that surrounds the receptor cells. Then there is an interaction with special proteins built into the cell membrane.
Such contact is possible if the shape of the stimulus molecule matches the shape of the protein. The mucous substance controls the accessibility of the receptor surface for odorous molecules.
After the stimulus molecule has come into contact with the protein receptor, the structure of the latter changes, as a result of which sodium ion channels in the membrane open. sodium ionspenetrate inside and create positive charges that lead to membrane depolarization.
A mediator is released from the receptor cell, which leads to the appearance of a nerve impulse in the sections of the nerve fiber. Thus, in the form of nerve impulses, olfactory excitation begins to be transmitted to other parts of the analyzer.
Operation of the olfactory system
If you imagine how the human olfactory analyzer works, then all the work can be divided into several stages:
- Promotion of an odorous stimulus to receptor cells, which ends with a connection with receptor proteins.
- Transformation of the chemical action 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.
- Movement of the nerve impulse to the lower nerve center. Can be interpreted as movement towards the olfactory bulb.
- Impulse transformation in the olfactory bulb.
- Promotion of nerve impulses to higher olfactory centers.
- Building an image of irritation in the form of a certain smell.
All these stages follow each other in sequence. If problems or disturbances are observed on one of them, it can be said that the perception of smells is impaired.
The habituation of the olfactory analyzer
We have analyzed the features of the human olfactory analyzer, but it is also worth noting that this sensory system is able to adapt. This happens with prolonged exposure to an irritant.
Adaptation of the analyzer can take place 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.
- Irritant concentrations.
- Air flow rates.
There is a fairly large group of odorous substances to which the olfactory analyzer adapts quickly. Very little time passes, and the smell ceases to be felt. A striking example is the complete adaptation to the smell of your body, room, things.
To some irritants addiction is formed slowly or even only partially. When exposed to a weak olfactory stimulus for a short time, addiction may manifest itself in the form of an increase in the sensitivity of this analyzer.
It has already been established that the development of adaptation occurs not in the first section of the analyzer, but in the last, that is, cortical. Often, when the same odorous substance acts for a long time, a persistent focus of excitation is formed in the cerebral cortex. In these situations, the sensation of smell can also occur when exposed to other stimuli. Sometimes this feeling can become intrusive and appears even in the absence of stimuli. In this case, we can talk about hallucinations, or illusions.
It can only be said with certainty that if there is an adaptation to one particular smell, then this will not affect the perception of other stimuli in any way, since all stimuli affectdifferent receptors.
Smell theory
Currently, more than 10 thousand odorous substances are known. All of them can be grouped into seven classes of primary odors:
- Floral.
- Mint.
- Musk.
- Ethereal.
- Rotten.
- Camphor.
- Caustic.
If there is a mixture of several odors, then its olfactory analyzer can perceive it as a completely new aroma. Molecules of various substances differ in different shapes, for example, the camphor smell has round molecules, and the musky one has the form of a disk. In addition, they also differ in electrical charge: some may have a positive, while others may have a negative one.
There are many theories that try to explain the mechanism of smell perception. Currently, the most common is stereochemical, which states that there are several types of sites on the membrane of receptor cells. They differ in their structure and electrophilicity. It is they who are able to recognize odorous molecules of a certain shape and size.
Varieties of olfactory disorders
In addition to the fact that the olfactory analyzer is not equally developed for everyone, in addition, some violations and deviations in its work can be observed:
- Anosmia is the complete absence of the ability to smell.
- Hyposmia is a decrease in the sense of smell.
- Hyperosmia, on the contrary, is observed with increased olfactory sensitivity.
- Parosmia characterizes inadequate perception of smells.
- Impaired differentiation.
- The appearance of olfactory hallucinations.
- Olfactory agnosia is set if a person smells, but cannot recognize it.
It should be noted that with age there is a gradual decrease in olfactory sensitivity. The olfactory analyzer is no longer able to recognize odors so clearly and quickly. Scientists have calculated that by the age of 50, the average person's sense of smell is reduced by half compared to youth.
Olfactory analyzer and its age features
The very first during the intrauterine development of the olfactory analyzer, the peripheral section begins to form. This happens as early as 8 weeks of development. By the end of pregnancy, or rather, by the end of the 8th month, this analyzer is already fully formed.
Already after birth, you can observe the reaction of the newborn to smells. This manifests itself in the form of facial movements, changes in the work of the heart muscle, breathing rate, body position.
It is with the help 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 ability of the analyzer to differentiate odors. The subtlety and strength of this process increases at the 4th month.
If we compare the ability to perceive and differentiate smells in children aged 5-6 and in adults, we can say that the latter have a much higher one.
These are the age features of the olfactory analyzer. It can also be said that as a result of systematic training, you can significantly improve your sense of smell, but heavy smokers risk losing their sharpness of perception, since the constituent components of tobacco smoke negatively affect the receptors. Also, frequent inflammatory diseases of the nasal cavity contribute to a decrease in the sense of smell.
So we have considered the olfactory analyzer. Its structure and functions are described with all possible accessibility. It is safe to say that all the sense organs are important for a person. If problems are observed in the work of at least one analyzer, then we can already say that the adequacy of the perception of the surrounding world is reduced, the fullness of sensations from life disappears. Take care of yourself and your senses.
