Histology of the respiratory system is one of the important branches of biology, which allows understanding the features of the organization of a living organism. Histology is usually called a science that is devoted to living tissues. To be more precise, the features of their structure, development, specifics of life. For the study of the histology of the respiratory system, a microtome is used, which allows dissecting samples into extremely thin layers. The discipline should not be confused with anatomy, as the object of study is different. The histology of the respiratory system gives an idea of the tissues of the body and the features of their structure.
General view
It is customary to talk about two sections of the human respiratory system. The foundation of classification is functionality. There are ways to move air masses. These include:
- cavity forming the inner space of the nose;
- nasopharynx;
- laryngeal region;
- tracheal elements;
- internal, external bronchial structures.
Doing what?
In the framework of the histology of the respiratory system, it is customary to talk about the following functionality of the ranked structures:
- carrying out airmasses;
- purification of the substance coming from the atmosphere;
- heating to body temperature;
- shaping sounds.
The structure of the respiratory system in histology is usually considered in relation to the second group of organs and tissues, called respiratory. The specialized name for this sector is acini. So it is customary to designate vesicles in the lungs located in the intercellular space. Thanks to them, it becomes possible to exchange gases with the circulatory system, which allows saturating the living organism with the necessary compounds.
How did you get there?
Private histology of the respiratory system is a frequent source of data for experiments and research, allowing you to get a general idea of the features of the development of organs, thanks to which the tissues of our body can receive oxygen. It is known that the foregut in the process of protrusion of one of the walls forms specific rudiments. It is from them that the bronchi, the tracheal region, and the laryngeal region are subsequently formed.
In the framework of gynecology and pediatrics, the histology of the respiratory system is also important, as it gives an idea of the period of formation of these tissues, which are most important for the normal life support of a living organism. It was revealed that the protrusion occurs already at 3-4 weeks from the moment of conception.
Mesenchyme is the source of differentiation, due to which the muscular bronchial tissue is formed. At the same time, the foundations of the cartilaginous structure are laid, and connective tissue fibers are born. As part ofstudies on the anatomy and histology of the respiratory system revealed that in the same period the circulatory system of the respiratory organs is formed. The splanchnotome is the basis for the development of the pleura.
Structure features
Histology of the human respiratory system made it possible to obtain an accurate picture of the features of the airways. In particular, it was found that, in fact, these are tubes that closely interact throughout the entire period of the body's life, capable of passing air masses. The inner surface is densely covered with a unique respiratory mucosa. Histology of the respiratory system showed that this tissue is characterized by ciliated epithelium, formed into a structure with a large number of rows.
At the same time, scientists have found that the vestibule of the nasal cavity is quite different from other organs. The histology of the respiratory system showed that there are certain differences in the structure of the area above the larynx, the vocal cords. Here the epithelium also consists of numerous layers, but is flat in structure.
Curious Moments
If we consider briefly the histology of the respiratory system, it is necessary to mention the features of the structure and functioning of the organs that form the pathways conducting air. In particular, their walls are created by multilayer fabrics. There are four shells in total:
- mucous;
- submucosal (glands are located here);
- fibrous cartilage (complemented with two types of cartilage tissue - hyaline, elastic);
- adventitial.
The severity of the shells varies significantly and is determined both by the peculiarity of the location and the functionality of a particular organ. If, in particular, one examines the structure of the bronchial system and pays special attention to the final, small structures, one can notice that the submucosa is completely absent here. There is no cartilaginous fibrous layer in such bronchi.
Mucoid
Normally, this element of the respiratory system is formed by a three-layer plate. It has several specific features. The first plate is epithelial. In its structure, it is a ciliated epithelium formed in many rows in the form of a prism. Such covers the respiratory structures. The second type is a plate created by loose connective fibers in combination with elastic ones. Finally, muscle is formed by myocytes (of an exceptionally smooth type). There is no such plate in the structure of the laryngeal region, trachea, or the inside of the nose.
Specific features of the trachea
This human organ, which provides the possibility of breathing, is a tube with four shells. From the inside, it is lined with mucous tissue, characterized by the presence of two plates. The base under the mucosa is a tissue supplemented with protein, mucous glands, which are distinguished by a complex structure, producing a specific secret. Thanks to this component, the surface of the trachea is always moistened from the inside. Outside, the organ is covered with adventitial tissue, and between it and the submucosa are cartilaginous, fibrous fibers.
By the way, not all living beings are arranged like people. In particular, the histology of the respiratory system of birds showed that they have no cartilage tissue in the trachea at all. Instead, a bone is formed here. Of course, histological studies make it possible to reveal certain similar features of the structure of organisms of various species, but one should not equate all forms of life with one another: there are surprisingly many species-specific differences.
Trachea: other features of the human body
As part of histological studies, it was found that the respiratory system in relation to this organ is supplemented with multi-row epithelium. It is formed by a wide variety of cellular structures:
- basal cambial;
- ciliated;
- mucus-producing goblet components;
- producing hormones serotonin, norepinephrine, dopamine endocrine.
The last category is responsible for the correct contraction of smooth muscles, since the process is regulated precisely by the hormonal background. If there are failures in the functionality of these cells, this can lead to serious pathologies of the respiratory system.
Tracheae: concluding the review
Another important aspect of the structure of the tissues of the respiratory system, revealed in the framework of histological studies, is associated with the features of the cartilaginous tracheal membrane formed by the fibers. As it was possible to find out in the course of specific experiments, this element is formed by rings of hyaline tissue in an amount from 16 to 20. Con the back side, they do not close, and the endings are connected by muscle bundles. Due to this structural feature, the tracheal walls are malleable. This sets the mechanics of swallowing, enabling food elements to be pushed through the esophagus towards the stomach.
Light
This organ is formed by a system of pathways that allow air masses to pass through. They are called bronchi. A complex structured system, the bronchial tree, was created from such objects. Respiratory functions are assigned to acini - bubbles systematized in the respiratory organs. They are also ordered and are an element of a complex object.
Bronchi
It is customary to single out several categories:
- basic;
- shares;
- belonging to zones.
The mentioned categories are classified as extrapulmonary. Along with them there are internal:
- segments,
- sub-segment;
- terminal.
Assessing the dimensions (in medicine it is customary to call it the caliber), it is customary to subdivide the bronchi into large, average, small, terminal. Regardless of belonging to a particular group, the structure of all varieties is quite similar in nature.
What is it about?
Normally, the bronchi are formed by four membranes. From the inside, the organs are covered with mucous tissue, under which there is a submucosa, the next layer is cartilaginous fibrous cells, and the final element is adventitial tissue. The diameter directly determineshow clearly each of the structural elements is pronounced.
If you examine the main bronchi, here you can see clearly formed four membranes. The same structural features are also characteristic of elements of large, medium size. But with a histological examination of small formations, only two layers can be found - mucous tissue and adventitial cells.
Bronchial mucosa
This element is formed by three plates: from epithelial cells, mucous tissue, muscle fibers. The epithelium is the layer facing the bronchial lumen. It is made up of ciliated cells, collected in a structure with an abundance of rows. The main characteristic of the epithelial layer is prismatic. The smaller the dimensions of the bronchi, the fewer rows will be in the structure of this element. Additionally, the nature of the cellular structure changes: in small organs, low cubic ones are predominantly found, but there are practically no goblet ones.
Histological examination of the distal parts of the respiratory system formed by the bronchi revealed the following types of cells:
- goblet;
- basal;
- ciliated;
- endocrine;
- bordered;
- devoid of eyelashes;
- secretory.
The last category is not typical for other departments of the bronchial tree. A feature of secretory formations is the ability to split the surfactant. But the limbic ones, as scientists have revealed, play the role of chemoreceptors. Finally, cells lacking cilia are unique to bronchioles.
What else to look out for?
Howrevealed during histological studies, the epithelium plate precedes the mucosa, created by loose connective cells. The structure of the plate determines the presence of elastic fibers. The smaller the dimensions, the higher the concentration of elastic formations. The third muscle plate acts as the closing one. Most developed in elements from major to minor. A distinctive feature of asthma affecting these organs is the contraction of muscle tissue of the smallest, small elements. The process leads to a decrease in the lumen of the respiratory organs.
The bronchial submucosal base is characterized by a grouping of protein, mucous mixed glandular cells - here are the end sections of these formations. The secret produced by cells is capable of destroying microscopic life forms, has a bacteriostatic effect. Due to its consistency, the secretion envelops dust particles and provides the necessary level of moisture to the mucosa.
Small, but daring
Small bronchial structure is devoid of the glands described above, submucosal. Quite atypical in comparison with other wood shell, created by cartilage cells, fibrous tissue. The smaller the size of the elements, the more this parameter changes. So, in the main structures, open rings were observed, but here there are only plates of cartilaginous tissue in large formations along the longitudinal direction.
What is special? Small bronchi are generally devoid of cartilage tissue,shell formed by cartilage, fibrous cells. The adventitial covering is made up of connective tissue fibers. They contain nerves, elements of the circulatory system. Gradually, the membrane flows into the lung septa of the parenchyma.
