Bronchi and lungs. Structure
The bronchi are all branches extending from the trachea. Together, they form a "bronchial tree." It has its own ordered hierarchy, which is the same for all people.
In the place of separation of the trachea at a practically right angle, a pair of main bronchi comes out of it, each of which goes to the gate of the left and right lung, respectively. Their shape is not the same. So, the left bronchus is almost twice as long as the right and narrower. This narrowness is the cause of the most rapid penetration of infectious agents into the lower respiratory tract through the shorter and wider main right bronchus. The walls of these branches are arranged like the walls of the trachea and consist of cartilage rings connected by bundles. However, unlike the trachea, the cartilage rings of the bronchi are always closed. In the wall of the left branch there are from nine to twelve rings, in the wall of the right branch from six to eight. The inner surface of the main bronchi is covered with a mucous membrane, the structure and functions of which are similar to the mucous membrane of the trachea. The branches of the lower link depart from the main branches (in accordance with the hierarchy). These include:
bronchial tubes of the second link (zonal),
bronchi from the third to fifth link (segmental and subsegmental),
bronchi from the sixth to the fifteenth link (small)
and terminal bronchioles directly associated with lung tissue (they are the thinnest and smallest). They pass into the pulmonary alveoli and respiratory passages.
The ordinal division of the bronchial tree corresponds to the division of lung tissue.
The lungs belong to the terminal section of the respiratory system and are paired respiratory organs. They are located in the chest cavity on the sides of the complex of organs, consisting of the heart, aorta, superior vena cava and other organs of the mediastinum. The lungs, in contact with the front wall of the chest and spine, occupy a large space in the chest cavity. The shape of the right and left parts is not the same. This is due to the fact that the liver is located under the right lung, and the heart is located on the left in the chest cavity. Thus, the right side is shorter and wider, and its volume is ten percent more than the volume of the left side. The lungs are located in the right and left pleural sac, respectively. Pleura is a thin film that consists of connective tissue. It covers the chest cavity both from the inside and outside (in the lungs and mediastinum). Between the inner and outer films there is a special lubricant significantly reducing the force of friction during breathing. The lungs are cone-shaped. The tops of the organ protrude slightly (two to three centimeters) due to the collarbone or the first rib. Their posterior border is located in the seventh cervical vertebra. The lower limit is determined by tapping.
Functions
The bronchus is an organ that is primarily responsible for delivering air to the pulmonary alveoli from the trachea. In addition, he takes part in the formation of a cough reflex, with the help of which small foreign bodies and large particles of dust are removed from it. Protective functions of the bronchus are provided due to the presence of cilia and a large amount of secreted mucus. Due to the fact that these organs are shorter and narrower in children than in adults, their blockage by edema and masses of mucus is easier. The bronchus function also includes the processing of incoming atmospheric air. These organs moisturize and warm it.
In contrast to the function of the bronchus, the lungs are responsible for the direct supply of oxygen to the blood, through the respiratory alveocytes and alveolar membranes.
Often there are complaints of pain in the bronchi. In this case, the cause of their occurrence should be established. Such sensations can be caused by both pulmonary infections and some other reasons. However, it should be noted that neither the lung tissue nor the bronchi have sensitive nerves, therefore they cannot “hurt”. The cause may be neuralgic, muscle or bone.