The histology of the respiratory system is one of the important sections of biology that allows one to understand the features of the organization of a living organism. Histology is usually called a science that is dedicated to living tissues. To be more precise, the features of their structure, development, specifics of life. To study the histology of the respiratory system, a microtome is used, which allows you to dissect samples into extremely thin layers. Discipline should not be confused with anatomy, since 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 parts of the human respiratory system. The classification is based on 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.
What is he doing?
As part of the histology of the respiratory system, it is customary to talk about the following functionality of the ranked structures:
- conducting air masses;
- cleaning the substance coming from the atmosphere;
- heating to body temperature;
- the formation of 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 you to saturate a living organism with the necessary compounds.
How did it appear?
Private histology of the respiratory system is a frequent source of data for experiments and research, which allows 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 anterior intestine during the protrusion of one of the walls forms specific rudiments. It is from them that the bronchi, tracheal region, and larynx are subsequently formed.
In the framework of gynecology and pediatrics, histology of the respiratory system is also important, as it gives an idea about the period of formation of these tissues, which are important for normal life support of a living organism. It was revealed that protrusion occurs already at 3-4 weeks from the moment of conception.
Mesenchyma is a source of differentiation, due to which muscle bronchial tissue is formed. At the same time, the foundations of the cartilaginous structure are laid, connective tissue fibers are born. In the framework of studies on the anatomy and histology of the respiratory system, it was revealed that in the same period the circulatory system of the respiratory organs is formed. Splanchnot is the basis for the development of pleura.
Structure Features
The histology of the human respiratory system made it possible to obtain an accurate idea of the features of the airways. In particular, it was revealed that, in fact, these are tubes that are closely interacting throughout the entire life cycle of an organism and are capable of passing air masses. The inner surface is densely covered with unique respiratory mucosa. Histology of the respiratory system has shown that atrial fibrillation is typical of this tissue, formed into a structure with a large number of rows.
At the same time, scientists found that the vestibule of the nasal cavity is quite significantly 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, vocal cords. Here, the epithelium also consists of numerous layers, but is flat in structure.
Curious moments
If we briefly examine the histology of the respiratory system, it is necessary to mention the features of the structure and functioning of the organs that form the air-conducting paths. In particular, their walls are created by multilayer fabrics. In total there are four shells:
- mucous membrane;
- submucosal (glands are located here);
- fibrous cartilage (supplemented by two types of cartilage tissue - hyaline, elastic);
- Advent.
The severity of the shells varies significantly and is determined both by the feature of the location, and the functionality of a particular organ. If, in particular, we examine the structure of the bronchial system and pay special attention to finite, small structures, we can see that the submucosa is completely absent here. There is no cartilageous fibrous layer in such bronchi.
Mucous
Normally, this element of the respiratory system is formed by a three-layer plate. She has several specific features. The first plate is epithelial. In its structure, it is a ciliary epithelium formed in many rows in the form of a prism. This covers the respiratory structure. The second type is a plate created by loose connecting fibers in combination with elastic. Finally, muscle is formed by myocytes (exceptionally smooth type). There is no such plate in the structure of the larynx, trachea, and the inside of the nose.
The specific features of the trachea
This human organ that allows breathing is a tube that has 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 differ in complex structure, producing a specific secret. Thanks to this component, the surface of the trachea from the inside is always moistened. Outside, the organ is covered with adventitious tissue, and between it and the submucosa there are cartilaginous, fibrous fibers.
By the way, not all living things are organized like humans. In particular, histology of the respiratory system of birds showed that in the trachea they generally do not have cartilage tissue. Instead, bone is formed here. Of course, histological studies allow us to identify certain similar structural features of organisms of various species, but you should not equate all life forms with one another: there are surprisingly many species-specific differences.
Trachea: other features of the human body
In the framework 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 cell structures:
- basal cambial;
- ciliated;
- goblet-producing mucous components;
- hormone-producing serotonin, norepinephrine, dopamine endocrine.
The last category is responsible for the correctness of smooth muscle contraction, since the process is regulated precisely by the hormonal background. If malfunctioning of the listed cells is observed, this can lead to serious pathologies of the respiratory system.
Trachea: Concluding Review
Another important aspect of the structure of the tissues of the respiratory system, identified in the framework of histological studies, is associated with the features of the cartilage tracheal membrane formed by the fibers. As it was found out during specific experiments, this element is formed by rings of hyaline tissue in an amount of 16 to 20. From the back side they do not close, and the ends are connected by muscle bundles. Due to this structural feature, the tracheal walls are supple. This causes the mechanics of swallowing, provides the ability to push food elements inside the esophagus in the direction of the stomach.
Lung
This body is formed by a system of paths that allow air masses to pass through. They are usually called bronchi. From such objects a complex structured system is created - a bronchial tree. Respiratory functions are assigned to the acini - blisters systematized in the respiratory organs. They are also ordered and are an element of a complex object.
Bronchi
It is customary to distinguish several categories:
- basic;
- shares;
- belonging to zones.
The mentioned categories belong to extrapulmonary. Along with them there are internal:
- segments
- subsegmental;
- terminal.
Assessing the dimensions (in medicine this is commonly called a 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, organs are covered with mucous tissue, under which there is a submucosal base, the next layer is cartilage fibrous cells, and the final element is adventitious tissue. The diameter directly determines how each of the structural elements is clearly, pronounced.
If you examine the main bronchi, here you can see clearly formed four membranes. The same structural features are also characteristic of large, medium-sized elements. But with a histological examination of small formations, only two layers can be found - mucous tissue and adventitious cells.
Bronchial mucosa
This element is formed by three plates: from epithelial cells, mucous tissue, muscle fibers. Epithelium - a layer facing the bronchial lumen. It is composed of ciliated cells assembled into a structure with an abundance of rows. The main characteristic of the epithelial layer is prismatic. The smaller the dimensions of the bronchi, the less rows will be in the structure of this element. Additionally, the nature of the cell structure changes: in small organs, mainly low cubic ones are found, but practically no goblet ones.
Histological examination of the distal sections of the respiratory system formed by the bronchi allowed us to identify the following types of cells:
- goblet;
- basal;
- ciliated;
- endocrine;
- limb;
- devoid of eyelashes;
- secretory.
The latter category is not characteristic of other parts of the bronchial tree. A feature of secretory formations is the ability to cleave surfactant. But limbic, as scientists have discovered, play the role of chemoreceptors. Finally, cells lacking cilia are characteristic only of bronchioles.
What else to look for?
As revealed by histological studies, the epithelial 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 a closure. Most developed in elements from major to minor. A distinctive feature of asthma affecting these organs is the reduction of muscle tissue in the smallest, smallest 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 - there are end sections of these formations. The secret produced by cells is able to destroy microscopic forms of life, has a bacteriostatic effect. Due to its consistency, the release envelops dust particles and provides the necessary level of moisture in the mucosa.
Mal yes
The small bronchial structure is deprived of the glands described above, submucosal. Compared to other trees, the membrane created by cartilage cells and fibrous tissue is rather atypical. The smaller the size of the elements, the stronger this parameter changes. Thus, open rings were observed in the main structures, but there are only cartilage tissue plates in large formations in the longitudinal direction.
What is the feature? Small bronchi are generally devoid of cartilage, the membrane formed by cartilage, fibrous cells. Advent coat is created by connective tissue fibers. They have nerves, elements of the circulatory system. Gradually, the membrane flows into the pulmonary septum of the parenchyma.