Breathing is the aggregate of processes providing continuous supply of oxygen to the tissues, the use of it in the oxidation reactions, and remove from the body formed during metabolism of carbon dioxide and partially water.
Breathing consists of the following main stages: external respiration, providing gas exchange between the light and the external environment; gas exchange between the alveolar air and flowing to the lungs venous blood, transport of gases in the blood; gas exchange between the arterial blood and tissues; tissue respiration.
External breathing - rhythmic process, the frequency of which in healthy adults is 16 - 20 cycles per 1 min. Each respiratory cycle consists of inhalation and exhalation. Inhale and exhale due to a change in the volume of the chest after the Tzimtzum and the relaxation of the respiratory muscles. If you increase the amount of chest pressure in the pleural cavity is reduced, and the air enters the lungs. When exhaling chest level decreases, the pressure in the lungs greater than atmospheric, and the air out of the lungs.
If you pin on the chest of a rubber cuff, filled with air and connected through the capsule Marea with easy lever, you can register respiratory movements of the chest. This method got the name of pneumography.
The alternation of inhalation and exhalation is due to automatic rhythmic activity of the respiratory center. Under the respiratory center understand the totality of nerve cells, regulating rhythmic process of external respiration and fixture breath to changing environmental conditions. Components of the respiratory center is located in the medulla, bridge (saralieva) and the midbrain. The activity of the lower divisions of the respiratory center is under the control of hypothalamic structures and bark of the big hemispheres. Part of the respiratory center includes inspiratory (the"center of breath") and expiratory neurons (the"center of breath").
The main factor influencing the initiation of the "breath", is carbon dioxide. During inhalation the alveoli of the lungs stretch that leads to irritation of mechanoreceptors, located in the alveoli. From them to the respiratory center in the wandering nerve do afferent excitation. With the gradual deepening of breath frequency afferent impulses is becoming greater. Under the influence of too much frequency of afferent activity "the center of breath" is braked and it exhalation.
Alveolar air (see Vital capacity of the lungs) carry out gas exchange with flowing to the lungs venous blood, as if internal gas medium of the organism. The composition of the alveolar air is constant changing not much in the normal breathing. During quiet breathing in the alveoli with every breath adult person receives 350 cm3 of the air, and the alveolar air is updated only 1/10 of their volume (coefficient of ventilation).
Minute ventilation of the lungs is the amount of air passing through the lungs for 1 min. Value minute ventilation increases dramatically when physical and emotional stress, which is explained by the strengthening of oxidative processes in tissues under these conditions.
The oxygen supplied from the alveolar air in the blood (see Gas exchange), binds to the hemoglobin in red blood cells and is delivered to the tissues. In tissue capillaries oxygen disrupted by oxyhemoglobin and goes into the tissues, where included in oxidative processes (see biological Oxidation). The carbon dioxide formed in the tissues, passes into the blood and enters the red blood cells. Then carbon dioxide combines with hemoglobin and delivered to the lungs. A large portion of carbon dioxide in the blood, with the participation of the enzyme carbonic anhydrase turns into bicarbonate, which pass in the plasma and transported to the lungs. In the lung capillaries bicarbonate using carbonic anhydrase disintegrate, carbon dioxide is released. Cleaved carbon dioxide and hemoglobin. Carbon dioxide goes into the alveolar air and exhaled air is removed into the external environment.
There are thoracic, abdominal, and mixed types of breathing. Types of breathing are developed and modified under diverse influences of the external and internal environment, especially under the influence of labor and sports exercises.

  • Pathological breath
  • Respiratory failure
  • Features breathing in children