Adult man takes from fourteen to twenty breaths every minute, and children, depending on age, are able to do up to sixty breaths in the same period of time. This is an unconditioned reflex that helps the body survive. Its implementation is beyond our control and understanding. External and internal breathing have a so-called communication between them. It works on the principle of feedback. If the cells do not have enough oxygen, then the body speeds up breathing, and vice versa.
Definition
Breathing is a complex reflex continuous act. It ensures the constancy of the gas composition of the blood. It consists of three stages or links: external respiration, gas transport and tissue saturation. Failure can occur at any stage. It can lead to hypoxia and even death. External respiration is the first stage in which gas exchange occurs between a person and the environment. Atmospheric air enters the alveoli first. And at the next stage, it diffuses into the blood for transportation to the tissues.
The mechanism of oxygen entering the blood is based on the difference in the partial pressure of gases. The exchange occurs along a concentration gradient. That is, blood with a high content of carbon dioxide easily takes in enough oxygen, and vice versa. At the same time, the essence of tissue respiration is as follows: oxygen from the blood enters the cytoplasm of the cell, and then passes through a chain of chemical reactions called the respiratory chain. Ultimately, carbon dioxide and other metabolic products enter the peripheral channel.
Composition of air
External respiration is highly dependent on the composition of atmospheric air. The less oxygen it contains, the less often the breaths become. The normal composition of the air is something like this:
- nitrogen – 79.03%;
- oxygen - 20%;
- carbon dioxide - 0.03%;
- all other gases - 0.04%.
As you exhale, the ratio of the parts changes somewhat. Carbon dioxide rises to 4% and oxygen decreases by the same amount.
The structure of the respiratory apparatus
The external respiration system is a series of tubes connected to each other. Before getting into the alveoli, the air goes a long way to get warm and clean. It all starts with the nasal passages. They are the first barrier to dust and dirt. Hairs located on the nasal mucosa hold large particles, and closely spaced vessels warm the air.
Then comes the nasopharynx and oropharynx, after them - the larynx, trachea, main bronchi. The latter are divided intoright and left lobes. They branch out to form the bronchial tree. The smallest bronchioles at the end have an elastic sac - the alveolus. Despite the fact that the mucosa lines all the airways, gas exchange occurs only at the very end of them. Unused space is called dead space. Normally, its size reaches up to one hundred and fifty milliliters.
Respiratory cycle
A he althy person breathes in three stages: inhale, exhale and pause. In time, this whole process takes from two and a half to ten seconds or more. These are very individual settings. External respiration largely depends on the conditions in which the body lives and on its state of he alth. So, there are such concepts as rhythm and frequency of breathing. They are determined by the number of movements of the chest per minute, their regularity. The depth of breathing can be determined by measuring the volume of exhaled air or the girth of the chest during inhalation and exhalation. The process is quite simple.
Inspiration is carried out during the contraction of the diaphragm and intercostal muscles. The negative pressure that is created at this moment, as it were, "sucks" atmospheric air into the lungs. In this case, the chest expands. Exhalation is the opposite action: the muscles relax, the walls of the alveoli tend to get rid of overstretch and return to their original state.
Pulmonary ventilation
The study of the function of external respiration helped scientists better understand the mechanism of development of significantthe number of diseases. They even singled out a separate branch of medicine - pulmonology. There are several criteria by which the work of the respiratory system is analyzed. Indicators of external respiration are not a rigid value. They may vary depending on the constitution of the person, age and state of he alth:
- Tidal volume (TO). This is the amount of air that a person inhales and exhales at rest. The norm is from three hundred to seven hundred milliliters.
- Inspiratory reserve volume (IRV). This is the air that can still be added to the lungs. For example, if after a calm breath, ask the person to take a deep breath.
- Expiratory reserve volume (ERV). This is the volume of air that will leave the lungs if, after a normal exhalation, a deep breath is taken. Both figures are about one and a half liters.
- Residual volume. This is the amount of air that remains in the lungs after a deep exhalation. Its value is from a thousand to one and a half thousand milliliters.
- The four previous indicators together make up the vital capacity of the lungs. For men, it is equal to five liters, for women - three and a half.
Pulmonary ventilation is the total volume of air that passes through the lungs in one minute. In an adult he althy person at rest, this figure fluctuates around six to eight liters. The study of the function of external respiration is necessary not only for people with pathologies, but also for athletes, as well as children (especially premature newborns). Often such knowledge is needed in intensive care, when the patient is transferred to a ventilator (artificial lung ventilation)or removed from it.
Types of normal breathing
The function of external respiration largely depends on the type of process. And also from the constitution and sex of a person. According to the way the chest expands, two types of breathing can be distinguished:
- Breast, during which the ribs rise. It predominates in women.
- Abdomen, when the diaphragm is flattened. This type of breathing is more typical for men.
There is also a mixed type, when all muscle groups are involved. This indicator is individual. It depends not only on gender, but also on the age of the person, since the mobility of the chest decreases over the years. The profession also influences him: the harder the work, the more the abdominal type predominates.
Pathological types of breathing
Indicators of external respiration change dramatically in the presence of respiratory failure syndrome. This is not a separate disease, but only a consequence of the pathology of other organs: the heart, lungs, adrenal glands, liver or kidneys. The syndrome is both acute and chronic. In addition, it is divided into types:
- Obstructive. Shortness of breath appears on inspiration.
- Restrictive type. Shortness of breath appears on exhalation.
- Mixed type. Usually it is the terminal stage and includes the first two options.
In addition, there are several types of abnormal breathing that are not associated with a specific disease:
- Chayne's Breath - Stokes. Starting from shallow, breathing gradually deepens and on the fifth or seventhbreath reaches normal levels. Then again it becomes rare and shallow. At the end, there is always a pause - a few seconds without a breath. Occurs in newborns, with TBI, intoxication, hydrocephalus.
- Kussmaul's breath. It is deep, noisy and infrequent breathing. Occurs with hyperventilation, acidosis, diabetic coma.
Pathology of external respiration
Violation of external respiration occurs both during the normal functioning of the body and in critical situations:
- Tachypnea - a condition when the respiratory rate exceeds twenty times per minute. It happens both physiological (after exercise, in a stuffy room) and pathological (with blood diseases, fever, hysteria).
- Bradipnoe - rare breathing. Usually associated with neurological diseases, increased intracranial pressure, cerebral edema, coma, intoxication.
- Apnea is the absence or cessation of breathing. May be associated with paralysis of the respiratory muscles, poisoning, traumatic brain injury or cerebral edema. There is also a symptom of stopping breathing during sleep.
- Dyspnea - shortness of breath (violation of the rhythm, frequency and depth of breathing). Occurs with excessive physical activity, bronchial asthma, chronic obstructive bronchitis, hypertension.
Where is knowledge of the characteristics of external respiration needed?
Examination of external respiration should be carried out for diagnostic purposes to assess the functional state of the entire system. In patientsfalling into a risk group, such as smokers or workers in hazardous industries, thus revealing a tendency to occupational diseases. For surgeons and anesthesiologists, the state of this function is important in preparing the patient for surgery. A dynamic study of external respiration is carried out to confirm the disability group and assess the ability to work in general. As well as during dispensary observation of patients with chronic heart or lung diseases.
Types of studies
Spirometry is a way to assess the state of the respiratory system by the volume of normal and forced expiration, as well as exhalation in 1 second. Sometimes, for diagnostic purposes, a test with a bronchodilator is performed. Its essence lies in the fact that the patient first undergoes a study. Then he receives an inhalation of a drug that dilates the bronchi. And after 15 minutes, the study again takes place. The results are compared. It is concluded that the pathology of the respiratory tract is reversible or irreversible.
Bodyplethysmography - performed to assess the total lung capacity and airway aerodynamic resistance. To do this, the patient needs to inhale air. It is in a sealed chamber. In this case, not only the amount of gas is recorded, but also the force with which it is inhaled, as well as the speed of air flow.
