The respiratory system is represented by various organs, each of which performs a specific function. The airways and the respiratory part are secreted in it. The latter includes the lungs, the respiratory tract - the larynx, trachea, bronchi and nasal cavity. The inner part is lined with a cartilaginous skeleton, due to which the tubes do not fall off. Also on the walls there is a ciliated epithelium, cilia that hold dust and various foreign particles, removing them from the nasal passage with mucus. Each section of the respiratory system has its own characteristics and performs a specific function.
Nasal cavity
Airways begin from the nasal cavity. This organ performs several functions at once: it holds foreign particles that enter the respiratory system together with air, allows you to hear smells, moisturizes, and warms the air.
The nasal cavity is divided into two parts by the nasal septum. There are choanas located at the back, connecting the airways with the nasopharynx. The walls of the nasal passage are formed by bone tissue, cartilage and lined with mucous membranes. Under the influence of irritants, it swells, becomes inflamed.
In the nasal passage, the largest is the septum cartilage. There is also a medial, lateral, upper and lower septum. On the lateral side are three nasal concha, between which there are three nasal passages. The upper nasal passage contains a large number of olfactory receptors. The middle and lower sections are considered respiratory.
The initial airways are connected with the paranasal sinuses: maxillary, frontal, ethmoid and sphenoid.
Nasal breathing
During breathing, air enters the nose, where it is cleansed, moisturized and warmed. Then he goes into the nasopharynx and further into the pharynx, where the opening of the larynx opens. In the throat, the digestive and respiratory tracts cross. This feature allows a person to breathe through the mouth. However, in this case, the air passing through the organs of the airways is not cleaned.
The structure of the larynx
At the level of the sixth and seventh cervical vertebrae, the larynx begins. In some people, its visually noticeable slight elevation. During the conversation, the cough of the larynx moves, following the hyoid bone. In childhood, the larynx is located at the level of the third cervical spine. In older people, they drop to the level of the seventh vertebra.
From below, the larynx passes into the trachea. The cervical muscles are located in front of it, the vessels and nerves on the sides.
The larynx has a skeleton represented by cartilage. In the lower part, the cricoid cartilage is located, the anterolateral walls are represented by the thyroid cartilage, and the upper hole is covered by the epiglottis. The back of the organ has paired cartilage. Compared to the front and side, they have a softer structure, due to which they easily change position relative to the muscles. Behind are carob, sphenoid and arytenoid cartilages.
In their structure, the airways are similar to many hollow organs: from the inside they are lined with mucous tissue.
The larynx has three departments: the lower, middle and upper. The anatomical complex structure differs in the middle section. On its side walls there is a pair of folds, between which there are ventricles. The lower folds are called voice. In their thickness are the vocal cords, which are formed by elastic fibers and muscles. Between the right and left folds there is a gap called the voice. In men, it is slightly larger than in women.
The structure of the trachea
A continuation of the larynx is the trachea. This airway is also lined with mucous tissue. The length of the trachea averages ten centimeters. In diameter, it can reach two centimeters.
The walls of the organ have several cartilaginous incomplete rings that are closed by ligaments. The wall behind the trachea is membranous, contains muscle cells. The mucous membrane is represented by ciliated epithelium and has many glands.
The trachea begins at the level of the sixth cervical vertebra, ends at the level of the fourth or fifth. Here, the trachea is divided into two bronchi. The bifurcation site is called a bifurcation.
The thyroid gland is adjacent to the trachea. Its isthmus is located at the level of the third ring of the trachea. The esophagus is located behind. Carotid arteries pass on both sides of the organ.
In children, the thymus is blocked in front of the trachea.
The structure of the bronchi
From the bifurcation site of the trachea, the bronchi begin. They depart almost at a right angle and go to the lungs. On the right side, the bronchus is wider than on the left.
The walls of the main bronchi have incomplete cartilage rings. The organs themselves are divided into medium, small and bronchi of the first, second, third and fourth order. In the small caliber there is no fibro-cartilaginous tissue, and in the middle there is elastic cartilaginous tissue, which replaces the hyaline cartilage.
First-order bronchi have a branching in the lungs into lobar bronchi. They are divided into segmental and further into lobular. Acinuses depart from the latter.
Lung structure
The airways complete the lungs, which are the largest organs of the respiratory system. They are located in the chest. On both sides of them are the heart and large vessels. Around the lungs is the serous membrane.
The lungs are in the shape of a cone with the base pointing towards the diaphragm. The apex of the organ is located three centimeters above the clavicle.
In the human lungs there are several surfaces: the base (diaphragmatic), costal and medial (mediastinal).
The bronchi, blood and lymph vessels enter the lungs through the mediastinal surface of the organ. They form the root of the lung. Further, the organ is divided into two lobes: left and right. At the front edge of the left lung there is a cardiac fossa.
The lobes of each lung consist of small segments, among which there is bronchopulmonary. The segments are in the form of pyramids, the base of which is facing the surface of the lung. Each organ has ten segments.
Bronchial tree
A section of the lung, which is somewhat separated from the neighboring ones by a special layer, is called the bronchopulmonary segment. The bronchi of this site are highly branched. Small elements with a diameter of not more than a millimeter enter the lobule of the lung, and branching continues inside. These small parts are called bronchioles. They are of two types: respiratory and terminal. For the latter, a transition to the alveolar passages is characteristic, and those end with the alveoli.
The entire complex of branching bronchus is called the bronchial tree. The main function of the airways is the gas exchange between the air filling the alveoli and blood.
Pleura
The pleura is the serous membrane of the lung. It covers the organ on all sides. The membrane passes along the edge of the lungs to the chest, forming bags. Each lung has its own individual membrane.
There are several types of pleura:
- Parietal (the walls of the chest cavity are lined with it).
- Diaphragmatic.
- Mediastinal.
- Costal.
- Pulmonary.
Between the pulmonary and parietal pleura is the pleural cavity. It contains fluid that helps reduce friction between the lungs and pleura during respiratory movements.
Lungs and pleura have different borders. At the pleura, the upper border runs three centimeters above the first rib, and the posterior one is located at the level of the twelfth rib. The front border is variable and corresponds to the line of transition of the rib pleura to the mediastinal.
The air-breathing organs perform a respiratory function. It is impossible to live without the organs of the respiratory system .