The human respiratory system is a set of organs that provide the function of external human respiration (gas exchange between the inhaled atmospheric air and the blood circulating in the pulmonary circulation). Gas exchange is carried out in the alveoli of the lungs, and is normally aimed at capturing oxygen from the inhaled air and releasing carbon dioxide formed in the body into the external environment.
An adult, being at rest, makes an average of 14 respiratory movements per minute, however, the respiratory rate can undergo significant fluctuations (from 10 to 18 per minute). An adult takes 15-17 breaths per minute, and a newborn child takes 1 breath per second. Ventilation of the alveoli is carried out by alternating inhalation (inspiration) and exhalation (expiration). When you inhale, atmospheric air enters the alveoli, and when you exhale, air saturated with carbon dioxide is removed from the alveoli.
A normal calm breath is associated with the activity of the muscles of the diaphragm and the external intercostal muscles. When you inhale, the diaphragm lowers, the ribs rise, the distance between them increases. The usual calm expiration occurs to a large extent passively, while the internal intercostal muscles and some abdominal muscles actively work. When exhaling, the diaphragm rises, the ribs move down, the distance between them decreases.
According to the method of expansion of the chest, 2 types of breathing are distinguished: [source not specified 2069 days]
- Thoracic type of breathing (expansion of the chest is made by raising the ribs), more often observed in women
- Abdominal type of breathing (expansion of the chest is produced by flattening the diaphragm), more often observed in men
There are upper and lower respiratory (air-conducting) ways. The symbolic transition of the upper respiratory tract to the lower is carried out at the intersection of the digestive and respiratory systems in the upper part of the larynx.
The upper respiratory system consists of the nasal cavity (lat. cavitas nasi), nasopharynx (lat. nasopharynx) and oropharynx (lat. mesopharynx). The system of the lower respiratory tract consists of the larynx (lat. larynx), trachea (other Greek τραχεῖα (ἀρτηρία)), bronchi (lat. bronchi), bronchioles, alveoli. The oral cavity, in case of difficulties in normal nasal breathing, although it can be used auxiliaryly for breathing, does not refer to either the respiratory tract or the respiratory organs and is not evolutionarily adapted for basic breathing.
Inhalation and exhalation is carried out by changing the size of the chest with the help of the respiratory muscles and the diaphragm. During one breath (in a calm state), 400-500 ml of air enters the lungs. This volume of air is called the “tidal volume” (TO). The same amount of air enters the atmosphere from the lungs during a quiet exhalation. The maximum deep breath is about 2,000 ml of air. After maximum exhalation, about 1,500 ml of air remains in the lungs, called the “residual volume of the lungs.” After a quiet exhalation, approximately 3,000 ml remains in the lungs. This volume of air is called the “functional residual capacity” (FRC) of the lungs. Breathing is one of the few bodily functions that can be controlled consciously and unconsciously.
Types of breathing: deep and shallow, frequent and rare, upper, middle (thoracic) and lower (abdominal). Special types of respiratory movements are observed with hiccups and laughter. With frequent and shallow breathing, the excitability of the nerve centers increases, and with deep breathing, on the contrary, it decreases.