Structure of the lungs

The lungs of a person are one of the most important organs, without which its existence is impossible. Breathing seems to us so natural, but in fact during it in our body there are complex processes that ensure our life. To gain a deeper understanding of them, it is necessary to know the structure of the lungs.

In the process of breathing, air passes through two bronchi, which have different structures. The left is longer than the right, but already it, so most often the foreign body penetrates the respiratory organs through the right bronchus. These organs have branching. When entering the lung, the right branches into 3, and the left one branches into 2 parts, which corresponds to the number of lobes of the lungs.

The structure of the lungs is quite complicated, because within them the bronchi branch into many small segmental bronchi. In turn, they pass into the lobular bronchi entering the lobules of the lungs. It is difficult to imagine what the structure of the lungs is, not knowing how many lobular bronchi is in them (there are about 1000 of them). Intraventinal bronchi have up to 18 branches (terminal bronchioles) that do not have cartilage in their walls. These end bronchioles form the structural component of the lungs - the acinus.

The structure of the lungs is easier to understand, understanding what the acini is. This structural unit is a collection of alveoli (derivatives of respiratory bronchioles). Their walls are a material substratum of gas exchange, and the area during a full breath can reach 100 sq.m. The greatest stretching of their respiratory surface occurs during physical exertion.

The bronchopulmonary segment refers to the part of the pulmonary lobe that is ventilated by bronchi of the third order branching off from the lobar bronchus. Each of them has a separate broncho-vascular pedicle (artery and bronchus). Segmental structure of the lungs was revealed during the development of the level of medicine and surgery. In the right lung there are 10 segments, and in the left lung - 8. Thanks to the fact that the division of the lungs into bronchopulmonary segments was established, it became possible to remove the affected parts of this organ with maximum preservation of its healthy parts.

In this organ it is common to distinguish the following surfaces: mediastinal, diaphragmatic, rib. In the mediastinum there are so-called "gates". Through them the lungs enter the bronchi, arteries and nerves, and the lymph vessels and pulmonary veins leave. All these formations constitute the so-called "root of the lung".

The lungs are separated by furrows of different depth and length. They divide the tissue up to the gates of the lungs themselves. There are 3 parts of the right lung (lower, upper, middle) and 2 left (lower, upper). Lower lobes are the largest.

The structure of the lungs will be incomplete without taking into account the visceral sheets of the pleura that cover each lung and the root region and form a "parietal leaf" lining the walls of the thoracic cavity. Between them is a slit-shaped cavity, part of which is called sinus (located between parietal sheets). The largest pleural sinus is rib-diaphragmatic (into which the edge of the lung descends when inhaled).

The structure of the lungs explains the processes occurring in them during breathing. In this organ, there are 2 systems of blood vessels: a small circle (consists of veins and arteries participating in gas exchange), a large circle of blood circulation (consists of bronchial arteries and veins delivering arterial blood to ensure metabolism and support the vital activity of the lungs). By the nature of its branching, the pulmonary veins are similar to arteries, but differ in their inconstancy. Their source is the capillary network of lobules, interlobular connective tissue, small bronchi and visceral pleura. Interlobular veins are formed from the capillary nets, merging with each other. Of these, larger veins pass near the bronchi. Of the share and segmental veins, two veins are formed in each lung: the lower and upper veins (their sizes vary greatly). They separate into the left atrium.

The number of bronchial arteries is not constant. It varies from 2 to 6. In 50% of cases a person has 4 bronchial arteries, going evenly to the left and right main bronchi. They are not exclusively arteries of the bronchi, because they give branches to different organs of the mediastinum. The beginning of the right arteries is located in the cellulose behind the esophagus and in front or under the trachea (between the lymph nodes). The left arteries are located in the cellulose below the trachea and under the arch of the aorta. Inside the lungs, the arteries are in the cellulose along the bronchi and, branching, play a direct role in the blood supply of the rest of its parts and the pleura. In respiratory bronchioles they lose their independent significance and pass into the capillary system.

All the blood vessels of the lungs are connected to each other. In addition to the general capillary network, there are out-of-organ and intra-organ anastomoses that connect both circles of the circulation.

The lymphatic system consists of the initial capillary nets, the intertwining of lymph vessels inside the organ, the draining vessels, extrapulmonary and intrapulmonary lymph nodes. There are superficial and deep lymphatic vessels.

The source of innervation of the lungs is the nerve plexuses and mediastinal trunks formed by the branches of sympathetic, wandering, spinal and diaphragm nerves.