Lungs

Structure of lungs

Easy are the bodies providing breath of the person. These pair bodies are located in a chest cavity, adjoin to heart at the left and on the right. Lungs have the form of semi-cones, the basis adjacent to a diaphragm, a top of speakers clavicles on 2-3 cm are higher. The right lung has three shares, left – two. The skeleton of lungs consists from is treelike the branching bronchial tubes. Each lung is covered outside by a serous cover – a pulmonary pleura. Lungs lie in the pleural bag formed by a pulmonary pleura (visceral) and covering from within a chest cavity pristenochny pleura (parietal). Each pleura outside contains the ferruterous cells producing liquid in a cavity between leaves of a pleura (pleural cavity). On the internal (cardial) surface of each lung there is a deepening – gate of lungs. The pulmonary artery and bronchial tubes enter gate of lungs, and there are two pulmonary veins. Pulmonary arteries branch parallel to bronchial tubes.

Pulmonary fabric consists of segments of a pyramidal form, the basis turned to a surface. The bronchial tube which is consistently sharing with formation of trailer bronchioles (18-20) enters top of each segment. Each bronchiole comes to an end with an acinus – a structurally functional element of lungs. An acinus consists of alveolar bronchioles which are divided into the alveolar courses. Each alveolar course comes to an end with two alveolar sacks.

Alveoluses are the semi-spherical protrusions consisting of connective tissue fibers. They are covered by a layer of epithelial cells and plentifully braided by circulatory capillaries. In alveoluses the main function of lungs – processes of gas exchange between atmospheric air and blood is carried out. At the same time as a result of diffusion oxygen and carbon dioxide, breaking a diffusion barrier (an epithelium of alveoluses, a basal membrane, a wall of a circulatory capillary), get from an erythrocyte to an alveolus and vice versa.

Functions of lungs

The most important function of lungs is gas exchange - hemoglobin supply with oxygen, a conclusion of carbon dioxide. Intake of the air enriched with oxygen and a conclusion saturated with carbonic acid is carried out thanks to the active movements of a thorax and a diaphragm, and also sokratitelny ability of lungs. But there are also other functions of lungs. Lungs take active part in maintenance of necessary concentration of ions in an organism (acid-base equilibrium), are capable to remove many substances (aromatic substances, ethers and others). Also lungs regulate a water balance of an organism: through lungs about 0,5 l of water a day evaporate. At extreme situations (for example, a hyperthermia) this indicator can reach 10 liters a day.

Ventilation of the lungs is carried out thanks to a difference of pressure. On a breath pulmonary pressure is much lower atmospheric thanks to what air gets in lungs. On an exhalation pressure in lungs is higher than atmospheric.

There are two types of breath: costal (chest) and phrenic (belly).

• Costal breath

In places of an attachment of edges to a rachis pairs of muscles which fasten one end to a vertebra, and to others – are located to an edge. There are external and internal intercostal muscles. External intercostal muscles provide process of a breath. The exhalation normal is passive, and at pathology the act of an exhalation is helped by internal intercostal muscles.

• Diaphragmal respiration

Diaphragmal respiration is carried out with participation of a diaphragm. In the weakened state the diaphragm has the dome form. At reduction of her muscles the dome is flattened, the volume of a chest cavity at the same time increases, pressure in lungs decreases in comparison with atmospheric, and the breath is carried out. At relaxation of phrenic muscles as a result of a difference of pressure the diaphragm holds a starting position again.

Breath process regulation

Breath is regulated by inspiratory centers and an exhalation. The respiratory center is located in a myelencephalon. The receptors providing breath regulation are located in walls of blood vessels (the chemoceptors sensitive to concentration of carbon dioxide and oxygen) and on walls of bronchial tubes (the receptors sensitive to change of pressure in bronchial tubes – baroreceptors). There are also receptive fields in a carotid sine (the place of discrepancy of internal and external carotid arteries).

Lungs of the smoking person

In the course of smoking lungs are exposed to the strongest blow. The tobacco smoke getting into lungs of the smoking person contains tobacco tar (pitch), cyanic hydrogen, nicotine. All these substances accumulate in pulmonary fabric, as a result the epithelium of lungs just begins to die off. Lungs of the smoking person represent dirty-gray or even just black mass of the dying-off cells. Naturally, functionality of such lungs is significantly reduced. In lungs of the smoking person dyskinesia of cilia develops, there is a spazmirovaniye of bronchial tubes therefore the bronchial secret collects, chronic pneumonia develops, bronchiectasias form. All this leads to development of HOBL – a chronic obstructive pulmonary disease.

Pneumonia

One of a widespread serious pulmonary illness is pneumonia – pneumonia. The term "pneumonia" includes group of diseases with a different etiology, a pathogeny, clinic. Classical bacterial pneumonia is characterized by a hyperthermia, cough with department of a purulent phlegm, in some cases (when involving in process of a visceral pleura) – pleural pain. At development of pneumonia there is an expansion of a gleam of alveoluses, accumulation in them exudative liquid, penetration in them of erythrocytes, filling of alveoluses with fibrin, leukocytes. For diagnosis of bacterial pneumonia radiological methods, a microbiological research of a phlegm, laboratory analyses, studying of gas composition of blood are used. A basis of treatment is antibacterial therapy.